Blow-up of projective variety $P^1 \times P^1..... \times P^1$ ($n$ times) and blow-up of $P^n$

Question: It is known that the blow-up of $P^1 \times P^1$ at a point is isomorphic to the blow-up of $P^2$ at two points. I'm wondering if there is any general statement for the blow-up of $P^1 \times P^1 \times.... \times  P^1$ ($n$ times) and of $P^n$.
Answer: The 'permutohedral variety' (the toric variety obtained from the permutohedron) is a very attractive toric variety which can be obtained by blowing up all of the toric strata in $\mathbb P^n$ in increasing order of dimension (i.e. all points first, then all lines, etc.). Similarly it can be obtained from $(\mathbb P^1)^n$ by blowing up two antipodal torus-invariant points and then all toric strata that meet these two points, again taken in increasing order of dimension. I learnt this from Dhruv Ranganathan's thesis (Theorems 54 & 55). It is by no means the minimal such construction (when $n=2$ it says that the blowup of $\mathbb P^2$ in three points is isomorphic to the blowup of $(\mathbb P^1)^2$ in two points) but it is certainly a very beautiful one.
Comment: This is nice. You can also consider only one point in $(\mathbb{P}^1)^n$ and only consider the toric strata in $\mathbb{P}^n$ contained in one toric hyperplane. This is minimal, at least in dimension $2$ and $3$ (see my answer below).
Answer: Yes there is such a general statement, except for the fact that (as Nicolas suggests in his answer) you need to consider sequences of blow-ups with centers at different subspaces, not just points. The statement I know well emerges in my paper "Toric varieties of Loday's associahedra and noncommutative cohomological field theories" with Sergey Shadrin and Bruno Vallette. Let me explain the way I see the case of $\mathbb{P}^1\times\mathbb{P}^1$ and $\mathbb{P}^2$; it is easily generalisable. The definition of the varieties below goes back to work of Laura Escobar on the so called brick manifolds.
In the case of $(\mathbb{P}^1)^{n-2}$ and $\mathbb{P}^{n-2}$, I am going to construct the desired varieties as parametrising certain collections of subspaces in $\mathbb{C}^{n-1}$ whose basis I will denote $e_{1,2}$, $e_{2,3}$, ..., $e_{n-1,n}$. I denote by $G(i,j)$ the subspace spanned by $e_{k,k+1}$ with $i\le k$, $k+1\le j$.
In the particular example $n=4$, we shall consider all possible choices of subspaces $V_{2,2}$, $V_{2,3}$, and $V_{3,3}$ of $\mathbb{C}^3$ in the following diagram

where the only information we have is that $\dim(V_{i,j})=j-i+1$ and that arrows are inclusions of subspaces; in general, this will become a trapezoidal shape of height $n-1$ with the prescribed left and right slope.
If we examine this particular picture starting from the bottom row, $V_{2,2}$ is a line in the two-dimensional $G(1,3)$, $V_{3,3}$ is a line in the two-dimensional $G(2,4)$, so choices of these two are parametrized by $\mathbb{P}^1\times\mathbb{P}^1$, and the ambient $V_{2,3}$ is uniquely reconstructed as $V_{2,2}+V_{3,3}$ unless $V_{2,2}=V_{3,3}$, in which case we see that $V_{2,2}=V_{3,3}=G(1,3)\cap G(2,4)=G(2,3)$, and we have $\mathbb{P}^1$ choices, so we have to do a blow-up of $\mathbb{P}^1\times\mathbb{P}^1$ at a point.
Similarly, going from the top of the figure, we may choose $V_{2,3}\subset G(1,4)$ first, which is $\mathbb{P}^2$ of choices, and then usually $V_{2,2}$ and $V_{3,3}$ are reconstructed uniquely as $V_{2,2}=V_{2,3}\cap G(1,3)$, $V_{3,3}=V_{2,3}\cap G(2,4)$, and non-uniqueness happens if $V_{2,3}$ coincides with either $G(1,3)$ or $G(2,4)$, in each case creating $\mathbb{P}^1$ of choices, so we get the blow-up of $\mathbb{P}^2$ at two points.
In general, there will be many different blowups at different centers but the general thing remains: creating the parameter space from the bottom row will give you a sequence of blow-ups of $(\mathbb{P}^1)^{n-2}$, and creating the same space from  the top row will give you a sequence of blow-ups of $\mathbb{P}^{n-2}$.
The varieties thus obtained happen to be toric, and this gives another perspective to the construction hinted at by Balazs in another answer.
It is also possible to have other examples; probably, the most famous instance of a variety that is obtained by blow-ups from both $(\mathbb{P}^1)^{n-2}$ and $\mathbb{P}^{n-2}$ is the Deligne-Mumford space of stable rational curves $\overline{\mathcal{M}}_{0,n+1}$ (the $(\mathbb{P}^1)^{n-2}$ part is very unsurprising since $n-2=n+1-3$, so the idea is more or less to take the first three points to $0,1,\infty$ and start blowing up diagonals, and for blowing up $\mathbb{P}^{n-2}$ you have to be a bit more inventive, and, for example, use the theory of wonderful compactifications of De Concini and Procesi).
Comment: Really nice answer !
Comment: Very nice. Can one use this though to get the Poincare polynomial/motivic identity implicit in Nicolas' approach? Does one get some interesting combinatorial identity?
Comment: @Balazs : I haven't done that calculation explicitly but yes, it can definitely be done. The coefficients of the Poincaré polynomial form, of course, the h-vector of the corresponding Stasheff polytope, so the total dimension of the cohomology is given by the appropriate Catalan number, and the individual Betti numbers are the "Narayana numbers", so I assumed that all combinatorial identities one will obtain will be known to experts in combinatorics, and did not spend too much time playing with them!
Answer: $(P^1)^n$ has Poincaré polynomial $(1+t^2)^n$, and $P^n$ has Poincaré polynomial $1+t^2+ \dots + t^{2n}$. If $X$ is of dimension $n$ and $B_pX$ the blow-up at a point $p \in X$ then $p_{B_pX}(t) = p_X(t) + t^2 + \dots + t^{2n-2}$.
If $B_r(P^1)^n$ is the blow-up of $(P^1)^n$ at $r$ points, and $B_s(P^n)$ the blow-up of $P^n$ at $s$ points, then equality of Poincaré polynomial implies that  $$(1+t^2)^n + r(t^2 + \dots + t^{2n-2}) = 1 + t^2 + \dots + t^{2n} + s(t^2 + \dots + t^{2n-2})$$ So we see that $r+n-1=s+1$, $r + \binom{n}{2}= s+1$, etc... and we easily see that this system that has no solutions if $n \geq 3$.
Of course, a less naive generalisation involving blowing-up at linear subspace could still work.
Answer: [This is a correction of an earlier answer, and is currently incomplete; thanks to Nicolas for pointing out that what I had written was totally wrong.]
Both varieties are rational. The obvious birational map between them  factors into a composite of smooth blowups and blowdowns. As they are toric varieties, they carry a dense torus action, and this factorisation is also equivariant. We can use toric geometry to try and see what happens (see Fulton's book Introduction to Toric Varieties for this language; the first few sections will suffice for what I am saying).
Consider the lattice $N={\mathbb Z}^n$ with standard basis $e_1, \ldots, e_n$. Then ${\mathbb P^n}$ corresponds to the toric variety given by the fan $\Sigma_1$ spanned by the lattice vectors $\{e_1, \ldots, e_n, -\sum_i e_i\}$, and all $n$-subsets of these vectors spanning top-dimensional cones.
The product ${\mathbb P^1}\times\ldots\times{\mathbb P^1}$ corresponds to the toric variety associated to the fan $\Sigma_2$ spanned by $\{\pm e_1, \ldots, \pm e_n\}$, and top-dimensional cones consising of points with all coordinates of fixed sign (the analogue of coordinate quadrants for $n=2$).
Consider the fan $\widetilde\Sigma_1$ obtained by inserting the lattice vector $-e_i$ into the interior of each maximal-dimensional cone of $\Sigma_1$ except the positive cone. Unless I am still making a mistake, it seems to me that the corresponding toric morphism $\widetilde{\mathbb P}_1\to {\mathbb P}^n$ is the blowup of $n$ disjoint points.
On the other hand, consider the fan $\widetilde\Sigma_2$ obtained by subdividing the cone in $\Sigma_2$ spanned by all the points with nonpositive coordinates using the lattice vector $-\sum_i e_i$. We get a toric one-point blowup
$\widetilde{\mathbb P}_2\to {\mathbb P^1}\times\ldots\times{\mathbb P^1}$.
The two toric varieties $\widetilde{\mathbb P}_1, \widetilde{\mathbb P}_2$ are defined using fans on the same set of 1-simplices $\{\pm e_1, \ldots, \pm e_n, -\sum_i e_i\}$, but the triangulations (sets of maximal cones)
are totally different for $n>2$. The birational map $\widetilde{\mathbb P}_1\dashrightarrow \widetilde{\mathbb P}_2$ can be understood as a composite of small birational modifications, corresponding to changes of triangulation between these two fans. I cannot see a systematic way to describe what happens; one can understand small $n$ explicitly.
Alternatively, as Nicolas also suggests, we should also be able to do further blowups/blowdowns to match the triangulations also, but I don't see a systematic way to do so.
Comment: (I deleted my now obsolete comment) Blowing-up along a $P^k$ add $t^{2k+2} + \dots + t^{2n-2-2k}$ to the Poincaré polynomial, so we could actually compute the exact values of how many linear subspaces of various dimensions we should blow-up in $\Bbb P^n$ to get at least there right number. The solution is probably as you said to understand how to relate the triangulations you introduced.
Answer: The blow-up of $(\mathbb{P}^1)^n$ at one point is always pseudo-isomorphic to the blow-up of $\mathbb{P}^n$ at $n$ points in general position.
To see this, let us consider, for each $n\ge 2$, the toric birational map $\tau\colon (\mathbb{P}^1)^n\dashrightarrow (\mathbb{P}^n)$ given by $$([x_1:1],[x_2:1],\ldots,[x_n:1])\mapsto [x_1:\cdots:x_n:1]$$
and which restricts then to an isomorphism on the affine space $\mathbb{A}^n$.
You can write $\tau$ as
$$ ([x_1:y_1],[x_2:y_2],\ldots,[x_n:y_n])\mapsto [x_1y_2\cdots y_n:y_1x_2y_3\cdots y_n:\cdots:y_1\cdots y_{n-2}x_{n-1}y_n:y_1\cdots y_{n-1}x_n:y_1y_2\cdots y_n].$$
and observe that it is the blow-up of the point $([1:0],\ldots,[1:0])$ followed by a pseudo-isomorphism (isomorphism if $n=2$, flop of three curves if $n=3$, ...) and then the contraction of the strict transforms of the hyperplanes given by $y_1=0,\ldots,y_n=0$ onto the toric points of $\mathbb{P}^n$ that are contained in the hyperplane at infinity.
You can also see the pseudo-isomorphism as blow-ups and blow-downs if you prefer (for instance, in dimension $3$ it is only $3$ disjoint Atiyah flops: blow-ups of three lines and contractions of three lines).
Comment: What is a pseudo-isomorphism?
Comment: A pseudo-isomorphism $X\dashrightarrow Y$ is an isomorphism $U\to V$ where $U\subset X$ is open, $V\subset Y$ is open and the closed subsets $X\setminus U$ and $Y\setminus V$ are of codimension at least $2$.


iPhone 2.5D code samples

Question: I'm looking for code samples that use 2.5D graphic for iPhone development. Anyone has some resources to share with?
Comment: What programming language do you want to use, or doesn't that matter? And is OpenGL okay?
Comment: objective c would be great. And yes, OpenGL is ok;)
Answer: For code samples, you might like to check out the cocos2d book from Apress. Chapter 11 deals with creating isometric '2.5d' games using tilemaps, which sounds like what you're looking for.
The Objective-C source code is available from the product page, but the book itself is well worth purchasing and reading.
Comment: +1, thanks for chapter 11. I've already learned cocos2d, but only to create 2d games

iPhone 2.5D code samples


Passport validity for entry into India

Question: Can an Indian passport holder (Indian citizen) enter India travelling from Australia with less than 6 months passport validity
Answer: As you are an Indian citizen, you have the right to enter India at all times
You are under no requirements to have 6 months validity on your passport but it must still be valid
Now, if you are transiting somewhere and require entry to that country for some reason, this may have an impact, but for India proper, you will have no issues
Comment: Make sure passport is not expired. Otherwise, airline will refuse you to board.

Passport validity for entry into India


1984 BMW 733i Trailer Attachment?

Question: I have a 1984 BMW 733i. I am curious if it is possible to attach a trailer hitch to it for connecting a light motorcycle trailer. It seems there is no connection for it but I am not totally sure just from looking.
Comment: Curt makes one for the 84 7 series sedan....http://www.curtmfg.com/part/11515#tab=vehicles
Answer: I used the 'U-Haul trailer hitch' (U-haul is a US based truck rental/towing company) website to search your vehicle, and it appears nobody makes a direct bolt on trailer hitch mount for your vehicle. Custom holes and a custom bracket will need to be drilled/fabricated for the rear sub-frame of your vehicle to mount a trailer hitch. It's not impossible, but it will cost you a few hundred USD.
Comment: Thank you. That is what I figured, but I couldn't tell by just looking under the rear of the car. The U-haul trailer hitch website seems like a good resource for this.

1984 BMW 733i Trailer Attachment?


how much do I really need to know to become Jr Developer?

Question: I believe I have a very good understanding of programming logic fundamentals (passing around variables, nested conditional statements, etc). I am currently going through a book on ASP.NET and am pretty much lost on all the Page Rendering Model, Custom Rendered Controls, Composite Controls, etc. I understand how to use the standard controls no problem. Do I really need to understand all those other things to become a junior developer? Any advice is appreciated!
Comment: Build a solid foundation - learn data structures and algorithms and then move up the stack.  It takes discipline but it's easier to learn higher level concepts once you understand the foundations.  It's much harder to learn the foundations if you've onl done higher level stuff and glazed over how things work.
Comment: Don't be afraid to try third party libraries like NHibernate, Log4Net, etc. Every object is a first class citizen in .net.
Comment: A little bit less than a senior developer.  :-)
Answer: A Junior Developer needs to have the basics down.  In your field, that would include a pretty firm grasp on OOP, the layout of ASP.NET applications, master pages, code behind (whether it be C# or VB.NET), etc.  Basically the stuff you can pick up with personal projects.  Everything else is just gravy.
The specifics, like composite controls and page rendering will be picked up and mastered while actually utilizing the certain technology.  Nobody is going to expect you to walk in the front door and be a master with ASP.NET.  You are young and your experience dictates that.  Even the best developers aren't born knowing this stuff.  They know it because they've used it....for many, many years.
BUT MOST IMPORTANTLY:
Just be willing to learn and listen to the mid-level and senior developers.
Answer: I think as a Jr Developer (I am one) you should be where you are at; solid knowledge of fundamentals, eagerness to learn and an open mind. You will consolidate your skills as you are introduced to new problems to solve. I think technology-specific skills are developed and learned on the job, at least that's what I've found. Good luck!
Comment: Not much actually. The point of being junior is that you have theoretical knowledge with little practical experience. Pharma_joe above said it well.
Answer: The truth is: it depends on company and on the meaning of junior position. Sometimes junior is equal to graduate and sometimes junior is above graduate.
Some companies expects that you know what ASP.NET is. Some companies expects that you know what .NET and C# is and some companies expects that you know what HTTP and web development is.
If junior = graduate you can find companies where simple diploma from information technology  related is enough (= theoretical knowledge) and company will teach you what they need. It doesn't mean you don't have to learn yourselves - self learning is the most important part of your career development.
The question is if ASP.NET WebForms are what you should learn? Definitely check ASP.NET MVC as well. Also being ASP.NET developer is not only about .NET - you should learn JavaScript and some JavaScript framework (like jQuery). Knowledge of HTML (especially HTML 5) and CSS can be also very useful.
Answer: i see your post and i amazed me that you are asking for Jr developer.
You just prepare your old projects what you have done in your college and company. after completing you'll see that you prepare some more new things and it will really help you to clear the Jr developer interview.


Experience editor showing home page instead of specific page on refresh

Question: While working in experience editor on certain page and when we refresh the page, the experience editor shows home page instead of that specific page. Now if we refresh the page again, the experience editor shows the desired specific page. Is this some issue with caching ?
Comment: Anything in the logs? Is the URL magically changing between refreshes? I would want to confirm that the sc_item query string is the same between refreshes. Does this happen in the web database context as well? Any custom redirects or URL rewrites in place?
Answer: I got this issue fixed.
There were 2 errors in the logs related to this issue.
ERROR Item could not be found from query string. [ID is "{D3893543-5018-448A-825F-C41472C6AA88}".]

ERROR Object reference not set to an instance of an object.
Exception: System.NullReferenceException
Message: Object reference not set to an instance of an object.
Source: Score.Custom at Score.Custom.ExperienceEditor.Ribbon.Duplicate.CanDuplicateRequest.ProcessRequest() at Sitecore.ExperienceEditor.Speak.Server.Requests.PipelineProcessorRequest`1.Process(RequestArgs requestArgs)

There were few customization done for the experience editor which checks the parent item of the page item which is opened in the experience editor. This customization was working fine until we enabled the enforce version presence feature. Once this feature was enabled, whenever there was no version for the parent item in th particular language then it throws null reference error and it cannot find the item.
This issue was fixed by disabling enforce version presence for the particular code.
using (new EnforceVersionPresenceDisabler())
{
  //Code
}


How can I forward mail in Domino 8.5.3 without keeping a copy in the original recipient's mailbox?

Question: I'm new to Domino and need to forward email that a user receives to another user. However, I do not want to keep a local copy of the message in the inbox of the original recipient. Can anyone explain to me how to do that?
Comment: Hi, I forgot to mention that I'm using Lotus domino 8.5
Answer: This is more of an admin question and here is the answer:
http://www-12.lotus.com/ldd/doc/domino_notes/Rnext/help6_admin.nsf/b3266a3c17f9bb7085256b870069c0a9/5dc869eda42a372e85256c1d0039546f?OpenDocument
Since I haven't used this feature before, I am not sure whether it will keep a copy in the intended recipient's mail box or not, but this is a step in the right direction, hope this helps. Let me know if you require further information.
If you find this solution useful, please make sure to mark it as accepted answer - thank you.
Comment: The documentation linked to also works for 8.5.x. You can use this if you want to forward ALL mails (it will not keep a copy).
Comment: Hi, this relate to domino server 6, I forgot to say that I use version 8.5.3, so thanks for the link but it's not reliable as things have changed alot since then and most information included there isn't right for new version.
Comment: Thank you for confirming that it will not keep a copy Per Henrik Lausten. Cividan unlike other technologies Notes does not need to and has not modified the base functionality for a while (they don't do a rip and replace for each version). So most of the documentation for v6 will be valid for the latest version, this makes it forward and backwards compatible - one of the beauty of using Notes. You can open a Notes 6 or even a Notes 5 db and it will work more or less without further modification in 8.5.3. Here is a link to 8.5.3 documentation: http://tinyurl.com/7a7szry.
Comment: Note, if you set up forwarding for a user as in the linked document, it will probably break the calendar functionality for that user, if they need it.


Confusion of how to use twitter bootstrap less file

Question: I'm getting mad over this confusion. I've installed twitter bootstrap through terminal then i install the gem file. After other small small formalities i've my bootstrap.less file in my assest pipeline. Now when i create a new view page and i want changes in the css so i just put those things in the newly created css.scss file in the assest pipeline. But after ive 2-3 css.scss files of different view files now i dont know why it is taking the definition of classes from different files.
For example
Ive one view file named as home.html.erb so the file of the same name is created in the assest pipeline named as home.css.scss. Now ive given some changes which i want only for this view page not for the other pages.
Now i ve another view page named as gallery.html.erb so this file automatically taking definitions from the home.css.scss. i dont why this is happening? Please help.
Answer: This is the Rails Asset Pipeline. It creates a .scss for each controller you've created. And it imports automaticaly to your views. In production environment, they all merged in one single file (in normal conditions).
Please, read this doc to understand how it works.


Definition of Touch Gestures

Question: Are there any non-platform specific definitions of touch gestures, that are typically used for devices like Android or iPhone.
I'm trying to write a specification for a multi-platform product that uses touch gestures. However, people have different opinions (depending on the platform they come from) what each gesture means.
So I was wondering if there is any "standard" definition on touch gestures. On Wikipedia this is the best I could find. But I'm sure people who are working on academic UI research must have some standard definitions.
EDIT: I just remembered that we have an UX site on StackExchange, so I asked the question there as well. Maybe someone can merge those. Not sure what the policy is on cross-posts.
Answer: You should take a look at jQuery Mobile. Their list is not comprehensive, but it's a good start for cross-platform definitions of touch gestures (tap, taphold, swipe, scroll).
http://jquerymobile.com/demos/1.0a4.1/docs/api/events.html

Definition of Touch Gestures


4G symbol appears but no/slow internet

Question: I have a Samsung Galaxy S21 5G which has worked great, but the last day or so I have been having a very annoying issue where the internet just goes really, really slow, yet it is still showing the 4G symbol in the corner.
Normally, when the internet goes slow, it'll show an 'H', then when it's really bad, an 'E', but while 4G is showing, its usually really quick. Since yesterday, it has been so slow to the point webpages time out, and some apps (such as reddit) fail to load at all (just get an error).
Today, it got more annoying where I actually got a "no connection to internet" appearing on my browser and app store, even though the 4G symbol is showing in the corner.
What I have tried:

Turning the phone off & on again
Removing and re-inserting SIM card
Turning aeroplane mode on/off
Reset Access Point Names to default (as per online tip)
Checking Network modes are set correctly

I'm not sure what else I can try. I am using the Virgin mobile network in the UK, which I believe is using the EE network, and their coverage checker tells me everything is fine and I should have good coverage.
Is there something I am missing, or anything else I can try as it's rather frustrating. WiFi works fine.
Comment: Couldn't it be a network provider's issue? That would be my guess...
Comment: Possible provider issue: https://istheservicedown.co.uk/status/virgin-media
Comment: @Robert That link times out every time
Comment: Hmm, I can open Robert's link fine. I also noticed Virgin Media mentioned this link to other reporters: https://my.virginmedia.com/faults/service-status
Answer: Options you have:

Check with other users who are on same network with different mobile.
Check with other users who are on same network with same mobile.
Get a new SIM card with same number. Yes, SIM cards can cause trouble.
If above 4 are checked, then it is the handset problem. Maybe a software factor reset can do a wonder too.

4G symbol appears but no/slow internet


Accessing terminal running in background

Question: I have a python script running on my rpi, which is starts from rc.local file. The script itself is working fine as it should, silently in background without opened terminal window. But in case I want to access the terminal it's running on and see the output how can I do that? Thanks!
Answer: It's not running in any terminal, so there's nothing to see.  Terminal is an interactive program that can use to start jobs and receive output.  Programs can run other ways - For example launched from graphical desktop or via script as you have done.
Comment: Thanks but the commands to log the information to the screen, aren't they going anywhere? Any suggestion on how can I manage this? Maybe run it in a "hidden" terminal somehow and then access it later somehow?
Comment: They log to "standard out" - That's the screen if you start from a terminal without doing something special, but it can generally be anything or nothing at all.


Scrum Sprint pre-story research

Question: When and who undertakes the work to sufficiently gather answers so that we can start to write stories for an upcoming sprint.  Is this work done continuously and in parallel to existing sprints by the product owner?  I guess this then creates tasks for a sprint such as investigate x and y.  What if the PO suddenly requires a developer to answer some of the questions by trying stuff out?  I understand the idea of spiking and creating r & d tasks.  I guess I want to avoid the main dev of a feature being delayed to a following sprint too often.
Comment: I'm voting to close this question as off-topic because it is not related to programming
Comment: Better suited at programmers....
Answer: The team determines how much new story work it can do during a sprint.  The amount of time they have to do that work is some percentage of the work day.  Depending on the responsibilities of team members (customer support, bug fixes, emails, PTO, other duties) that amount varies from team to team.  I like to see 10-15% of the work day dedicated to "planning" for the next sprint.  That includes helping the PO research, writing stories, breaking up stories, design sessions, what-if scenarios, etc.  I think the key is not to shoe-horn every one of these types of tasks into a sprint but rather to set the correct time allocation to doing the sprint work.  Maybe something like 30 hours/wk is an average number.
So to directly answer your question; the planning work is done in parallel to the current sprint work.
Answer: We usually have one or two meetings to talk about future stories. Also, we reserve some overhead time in each sprint to check out things we need to know to start a story. The meetings help determining which stories will probably shop up in the next sprint, so we know which questions to get answers to during the reserved time in the current sprint.
Answer: For us, if it's a large project, we will have kickoff meetings to brainstorm the project.  There is often a knowledge gap for PO's between what they want to do and what they don't know we can do that these meetings can fill.
When new stories are created, we try to assign story points to them at some point before the next planning meeting so the PO has time to prioritize the list before that meeting.
I'm not sure of the kind of situation you describe where a PO would "suddenly" need a dev to try stuff out.  In that case, I would offer a spike in the next sprint.  Generally using new technologies isn't something that happens every sprint so this should suffice.  If not, perhaps the sprints are a bit too long for this purpose (a trade off to be considered at least)  Another alternative would be to introduce an evergreen story for trying stuff out.  I've seen teams have these kinds of stories for tech debt payback - you could off an either/or situation.  Sometimes dev fixes tech debt, sometimes they try stuff out.  And if you run out of tech debt somehow, you can always grab another regular story to put in its place.
Answer: We typically reserve a sprint or two after a big release for research and proof of concept stories. Doing research as part of the regular sprint seems like it would be problematic. You'd probably use that time to absorb mis-estimations for value-adding stories and end up never using it for actual research.
If a new story drops into the backlog that needs research and the PO runs it up to the top of your backlog then the team should include some research time into their actual estimate. I would only do that if I didn't have the luxury of a research/prototyping sprint ahead of time though since estimating research can be a bit nebulous.
Answer: Who: Product owner. Stories and Product backlog are his responsibilities. Product owners are generally experienced people; even if they are not technical they can certainly perceive implementation complexities at abstract level. Still, if a story has gray area PO must ask right people the right question. He can ask developers, testers, peers, clients and even scrum masters.
When: all the time.. Continuously. PO must not do anything but (1) provide (or get) answers for the team's questions regarding scope and function, (2) and gather data that would refine the stories and their scope: thus proactively solving the queries of his team.
Bottom line is if product owner is not giving good stories to the team then he is not doing his job. Stories can be written by anyone but in the end it's PO who ensure that Product Backlog is in order and that top priority stories are defined.

Scrum Sprint pre-story research


What are the paintings in the Anti-Angel Headquarters and what do they mean?

Question: There is a partial list available on Fandom and a full list of the symbols without explanation on a Japanese wiki site. What do the ever-changing paintings mean and how are they connected to the episode's or the overall plot?
Answer: Directions are relative to Yuri as she sits at the principal's desk facing the entrance.
For the sake of completeness, I also include the paintings that are fixed across episodes.

All episodes

Front: School song of the Heaven Academy.
The song lyrics reproduced below reference this yahoo answer and this wiki page.

校歌
緑豊かに広がる丘に
光輝く我らが母校
大いなる大地と
天のかけ橋
真実を知る時天に登らん
心のままに戒めなくは
かけ[●●●●●●●●●]【し希望にひるがえる】
千里離れた空を思へば
遠く忘れし思いはいづこ
真実を知る時天に登らん
光あふれる月の夜
耳をすまして聞き入れば
天使の歌声高らかに
思いを胸に登る[●]【時】
真実を知る時天に登らん
天上学園

Back: Portraits of all past principals of the Heaven Academy.
The portrait of the current principal has been replaced by Yuri's.
Left: During the operation meetings, the banner of the SSS Brigade is hanged on this side of the wall.
Right: Smiley face painting.
Unknown artist.

Episode 1

Front: [危]【き】 — Danger.
Left: テトラポット — Tetrapod.
Right: [南紀]【なんき】みかん — A brand of mikan from Nanki, Mie Prefecture.
Note that Jun Maeda, the creator of Angel Beats!, is from Mie.

Episode 2

Front: [毒]【どく】 — Poison; short for [毒舌]【どくぜつ】, or sharp tongue.
I believe it's also intended to invoke the expression 「[お気の毒に]【おきのどくに】」, meaning "my condolences", as said by Angel about Hinata in episode 5.
By Jun's arrangement or by coincidence, Hinata is forced into sacrifice in an arithmetic progression of episode numbers 2, 5 and 8.
Left: [悦]【えつ】 — Rejoicing.
"Why does Yuri smell so good?"
Right: [松阪牛]【まつさかうし】 — Matsusaka beef, another food product from Mie.
A jab at Matsushita's fate in this episode?

Episode 3

Front: [嫁]【よめ】 — Wife; bride; daughter-in-law; to pass the buck ([(転)嫁する]【(てん)かする】).
Left: [諭吉]【ゆきち】 — Yukichi Fukuzawa, the guy on the 10,000 yen banknote.
Yukichi is a nickname of Yuuki Hashimoto from the 2010 eroge Koiiro Soramoyou who is also voiced by Harumi Sakurai, Yurippe's voice actress, under the alias Kazane.
Moreover, "Farewell, Yukichi" is the defining quote of Kyousuke Natsume from Little Busters!, another visual novel written by Jun Maeda.
Right: マニア — Mania.

Episode 4

Right (OP): [鎮魂歌]【ちんこんか】 — Requiem.
Alludes to both the album Requiem for Innocence by Sad Machine that has had a profound influence on Masami Iwasawa as well as Iwasawa's passing on at the conclusion of the last episode.
Front: [脇]【わき】 — Supporting character; the second stanza of a renga.
At this point in time, the story has entered its second phase in the hokku→waki→daisan→hiraku→ageku renga structure, or the introduction→development→twist→conclusion kishoutenketsu structure.
Left: (Not shown).
Right: [逆鱗]【げきりん】 —  A scale grown upside-down below the chin of a dragon that will anger the dragon when touched; imperial wrath.
Yuri's underlings incurred her wrath by failing their mission of defeating Angel's team in the baseball tournament.
There is also the angered dragon conjured up in Otonashi's mind in episode 7.

Episode 5

Front: [謎]【なぞ】 — Mystery, i.e. Ayato Naoi the usurper.
If you turn up the volume just after Yuri throws her second tantrum, you can also hear a "mysterious voice" saying "what's with her?" (「なんだこいつ」).
This is documented under the 謎の声 section here.
Left: コテンパン — Beaten black and blue, i.e. Angel and Hinata, and Ooyama and Takamatsu, in this episode.
Right: バミューダ — Bermuda, one of the endpoints of an area known as the Bermuda Triangle, famous for the disappearance of a number of aircraft and ships within this region under mysterious circumstances.

Episode 6

Front: [乙]【おつ】 — The ordinal "second"; a prefix meaning young and charming, e.g. [乙女]【おとめ】.
Also resembles the "Z" mark of Zorro.
Left: (Not shown).
Right: [猫大陸]【ねこたいりく】 — Continent of cats?
Presumably the same painting appears again in the second panel on page 4, chapter 30 of Angel Beats! The 4-koma: Our War Front March Song:

In this panel, Yusa is explaining the term "marriage hunting" ([婚活]【こんかつ】) to Hinata.
Starting this episode, Otonashi began to hit on Kanade, and Naoi even arranged for their "marriage hunting" activities to take place inside the reflection room for maximum privacy!

Episode 7

Front: プラ — Recycling symbol used in Japan for plastic.
Left: [濃厚]【のうこう】 — Rich in flavor, color, odor, etc.; probable; passionate and sensuous.
Right: [●●ック]【ファック】? (Not legible).
Could be the f-word.

Episode 8
Front: (Not shown).
Left: (Not shown).
Right: (Not shown).

Episode 9

Front: ♨ — Icon for hot springs.
Left: [部族]【ぶぞく】 — Tribe; clan.
Right: マグロ? (Not fully shown) — Tuna.

Episode 10

Front: (Not shown).
Left: ●ロス? (Not legible).
Right: [赤福]【あかふく】 — Akafuku, a wagashi shop in Ise City, Mie Prefecture, known for their Akafuku mochi, or [赤福餅]【あかふくもち】.

Episode 11

Front: (Not shown).
Left: (Not fully shown).
Right: [極上]【ごくじょう】 — First-rate.

Episode 12

Front: [心]【こころ】 — Heart.
Lots and lots of hearts on the computer screens.
Left: (Not shown).
Right: [土]【ど】● (Not fully shown).

Episode 13

Front: [魂友]【たまとも】 — Soulmate.
A possible play on words of Tama-Tomo, or best friends in the Tamagotchi Planet.
Left: (Not shown).
Right: (Not shown).

Special: Another Epilogue

Front: (Not shown).
Left: (Not legible).
Right: [東]【とう】●? (Not legible).
It would make more sense if the character is [転]【てん】, though, as that means "change in pronunciation or meaning of a word".

OVA 1: Stairway to Heaven

Front: (Happy face).
Left: (Teeth-gritting face).
Right: (Happy face).

OVA 2: Hell's Kitchen

Front: [再]【さい】 — Again.
Left: ボンレス — Boneless.
Right: [久々]【ひさびさ】 — (in a) long time; long time (ago).
It's been almost 5 years since the last Angel Beats! episode was released.

Kaginado (Season 2)

Front: [鍵]【かぎ】 — Key.
Left: [暴君]【ぼうくん】 — Tyrant.
Right: [生徒会長]【せいとかいちょう】 — Student council president.
Right (Episode 3): カオス — Chaos.
Right (in place of the smiley face painting): A Keropii painting annotated with the year of Key's debut game, Kanon.
Keropii is the favorite frog plush toy of Nayuki Minase, one of the five heroines of Kanon.
Comment: Episode 7, the front one is the recycling sign for plastic: http://en.wikipedia.org/wiki/Recycling_in_Japan
Comment: Epi 9, front, is the icon for hot springs.


How to dynamically get items from Json feed

Question: I need to pull and display some json data from a google stock feed:
https://finance.google.com/finance/info?client=ig&q=NYSE:BHP
The only catch is I don't know what the data is. The customer would like to pass in a list of comma separated values to tell my code what items to pull.I would therefore plan to pass in an array of named items to tell the feed which items I want values for, so in theory to match the incoming values with the equivalent json item names. It wont always be the same items or number of items.
How can I do this dynamically (I am using json.net) ?
Sample Json Data:
[{
    "id": "4905",
    "t": "BHP",
    "e": "NYSE",
    "l": "26.90",
    "l_fix": "26.90",
    "l_cur": "26.90",
    "s": "0",
    "ltt": "6:01PM EST",
    "lt": "Dec 2, 6:01PM EST",
    "lt_dts": "2015-12-02T18:01:42Z",
    "c": "-0.41",
    "c_fix": "-0.41",
    "cp": "-1.50",
    "cp_fix": "-1.50",
    "ccol": "chr",
    "pcls_fix": "27.31"
}]

Sample of CSV values the user might pass in:
t, e, l, cp_fix
Answer: You can use the json class from System.Web.Helpers namespace to deserialize json string into a dynamic object. like below:
dynamic Data = Json.Decode(json);

It is included with the MVC framework as an additional download to the .NET 4 framework. Than you can access the properties you want using Data.PropertyName


How can you test your web server speed?

Question: Our website seems to be slower than it used to be, how can I test that? And is there a way to find the cause? (eg too many visitors).
Thanks.
Answer: There is a rather good tool for performance benchmarking of web servers: Jakarta Jmeter, which is an Apache project, so it's rather well supported and tested.
The key to be able to pinpoint the cause would be to do benchmarking regularly, so you can actually match changes in your benchmark results with events on your server: upgrades, code changes, variations in the number of visitors...
Answer: The Firebug add on for Firefox has a Net tab which is useful for debugging issues and testing. Also Fiddler on Windows is nice. And then there is the age old tradition of checking your server error logs for any problems.
Answer: A good first step is to make sure you are keeping fairly complete server logs and feed them into a log analyser. This is helpful for giving you a general idea of how long things take and which pages are slowest. It's also a good idea to check your error logs to make sure things are working properly.
Beyond that, things get more complicated as you may need to isolate your webserver, code and database to see if one of these is the bottleneck. Also, Jeff's blog, coding horror had a recent entry on server optimization.
Answer: Use Google Analytics to track your site's visitors over time to find out if you are getting more traffic.
You tagged your question with shared-hosting - being on a shared host means that someone else's code running on the same machine as your may be affecting your site's performance.
I'd suggest going with Varkhan and apphacker's suggestion to make sure your site's code is reasonably quick. use Analytics to get some stats and the possibly, depending on how many visitors you are getting and how slow the site is, consider moving away from a shared host.
Answer: Try the server speed checker at Bitcatcha.com. The tool ping your website server and record the time needed to get a response. It also pings from 8 different nodes to your server. You are able to at least find out whether it's your server that is slowing your website.

How can you test your web server speed?


How could I test if a player is holding a specific item in slot 0 in Minecraft 1.7.9/10?

Question: My question is how could I go about testing if a player is holding an Enderpearl in Slot 0 without mods, plugins or updates?
Comment: Take a look at http://gaming.stackexchange.com/questions/173025/check-if-player-has-item-if-so-remove-it/173038#173038
Comment: You must use /detectitem in a command block in a 1.8 snapshot.
Comment: @Titilolo3 it says in the question he isn't using 1.8 snapshots
Answer: You can't. The SelectedItem and SelectedItemSlot data tags are new in Minecraft 1.8. Furthermore, testfor can only check NBT data as of Minecraft 1.8. The scoreboard command checking players based on NBT data is new as of 1.8 as well. Therefore, the only way to be able to do this is to update to Minecraft 1.8.
But let's say you do update to 1.8. You can do a simple testfor and get a redstone output like so:
/testfor @a {Inventory:[{Slot:0,id:"minecraft:ender_pearl"}]}

This will output a redstone signal if any player has an ender pearl in slot 0 (it doesn't check if they have slot 0 selected, though; to do that, change the above data tag to {SelectedItemSlot:0,Inventory:[{Slot:0,id:"minecraft:ender_pearl"}]})
This command isn't particularly useful though. All it does is output a redstone signal if any player meets the criteria. In order to do anything with it, /scoreboard becomes your best friend. To start, create a dummy objective:
/scoreboard objectives add pearls dummy

Next, we want to reset this score for all players, and then set it to 1 for players with a pearl in slot 0:
/scoreboard players set @a pearls 0
/scoreboard players set @a pearls 1 {Inventory:[{Slot:0,id:"minecraft:ender_pearl"}]}

Now you can actually use this information in a target selector, by using @a[score_pearls_min:1] as your player argument in other commands.
But the short answer to your question, if you really don't want to update, is you can't.
Answer: You can't detect an item in an specific slot in 1.7. In 1.8 you can. The best you can do is detect wether or not an item in in a player's inventory, regarless of the slot using a comparator and the /clear command clearing 0 items.
Answer: You can't...
The best you do in versions before 1.8 is test if the player has a item in their inventory with the command /clear @p minecraft: (item name) 0 0 by updating to 1.8 you can use the command /testfor @a {Inventory:[{Slot:0,id:"minecraft:ender_pearl"}]} But.. that won't be much use without scoreboards
Comment: Please don't capitalize the first letter of every word. It makes the text way harder to read.
Comment: In another note: are you sure the clear command just checks the content of an iunventory? to me that sounds like it would remove that item. (I did not check this on the wiki, so I could be mistaken)
Comment: @Arperum, he uses a max count of 0, so it will try to clear at most 0 items, and it will fail if you don't have the item.
Comment: @penne12 Ooooh... I learned something today.


Can we see everything?

Question: OK so light bends and light is color, so if I was in a hallway with both sides closed and a mirror on each end of the hallway that takes up all of the wall facing me, a mirror above me that takes up the whole ceiling , and the other mirrors tilted slightly up towards the mirror above me. Then if I look into the mirror in front of me and light bounces off that mirror and hits the mirror above me which reflects to the mirror behind me, in the mirror I'm facing would I be able to see endless light duplicates of me. Would it be any different if there was a mirror on the ground that covered the whole hallway? So I guess what I'm asking is that if you had photons inside of a glass prism then where does that light go?
Comment: That's... not how Stack Exchange works, Zachary. Content can be edited - for example to improve the grammar or spelling - by anyone who's earned that privilege.
Comment: Please look at my profile before voting commenting answering it or leaving a comment and please ask before you edit
Comment: K it's just someone was messing around with my last question so I deleted it
Comment: Regarding your previous post, if it was deliberate "messing around" with no good intention behind it, you could flag it. There is  a record of the edits users make, I am pretty sure.
Answer: I don't think this is much different in principle, from holding a mirror in your hand and looking at yourself in another mirror.
After each bounce, the reflections will lose their intensity and they will increasingly lose  focus/ sharpness. The image will eventually fade away, as the mirror never reflects 100 percent of the light. If you have a larger distance between yourself and the mirrors, as I think your question implies, this increases the rate of this fade out of the original image and you will also get less reflections than you would in my above paragraph.

Can we see everything?


What did Jesus mean when he said salvation is from the Jews?

Question: John 4:22 ASV says, Ye worship that which ye know not: we worship that which we know; for salvation is from the Jews.
What did Jesus mean with his statement "salvation is from the Jews"?
Comment: Messiah was to come from the tribe of David, and salvation through this Messiah, i.e. through Him, who was that very Messiah. Although, majority of Jews understood Messiah in political terms as liberator of Jews from political oppressors, Romans, in that particular setting. However, the Lord Jesus Christ gave liberation from sins, which is only God's prerogative.
Answer: "Salvation is from the Jews."  The statement has a general form, but Jesus was particularly telling the Samaritan woman that between the Jewish and Samaritan ways of worship, the Jewish way was the true way and from it came salvation.
The Jews regarded Samaritans as heretics because the latter believed God's dwelling place to be Mt. Gerizim (Jn 1:20) near Sychar (where the Samaritan woman lived) instead of Mt. Zion in Jerusalem (1 Kgs 8:29). The Samaritans believed Mount Gerizim was where Abraham was asked to sacrifice Isaac, although  Scripture records that location as Mount Moriah (Gn 22:1–19). They also believed Gerizim was where Jacob had his dream, rather than in Bethel farther south (Gn 28:10–22.)
Samaritans were said to observe Jewish rites and practices superficially, but did not know the meaning (spirit) of such practices. (Jn 4:22)"You Samaritans worship what you do not know." And that might be the reason she could not get out of the rut of sin, for the Jews accused Samaritans of having demons. (Jn 8:48). On the other hand, the Jews' rites and practices were the true and correct form (Jn 4:22) "we worship what we do know."
However, Jesus said there will come a time when neither Jewish nor Samaritan religions will be sufficient to obtain salvation, but only the kind that "worships the Father in spirit and in truth." (Jn 4:23)
The woman agreed and believed the Messiah would come but until then, there was no need to trouble herself with the spiritual and true worship (Jn. 4:25). Jesus said, "There will come a time, and the TIME IS NOW…" (Jn 4:23) and this led to his revealing himself as the Messiah.(Jn 4:26)
"Salvation is from the Jews."  Aside from the obvious reason that Our Lord Jesus Christ was from the Jews, the Apostles' preaching of the Gospel also started in Jerusalem. (Acts 1:6-9)
It is true that salvation came from the Jews but it did not stay with them.  "He came to his own but his own received him not." (Jn 1:11)  "But to those who did accept him he gave power to become children of God, (Jn 1:12) "to those who believe in his name (whether Jew or Greek, male or female, slave or free, doesn't matter - Gal. 3:28), "who were born not by natural generation (not of Jewish ancestry) nor by human choice nor by a man's decision but of God." (Jn 1:13).
Comment: Welcome to BH and thanks for this contribution. Do read the tour to see how this site works. You say "Samaritans were heretics"  but do not give a Bible reference to back this up. You might like to consider editing in some more references so that we can see where every assertion is coming from.
Comment: Thanks for the suggestions, C. Stroud.  I hope my edits are satisfactory for now.  Merry Christmas, and God bless you.
Answer: Here are some related background questions:
Orthodox Jews take Deut. 12:5 to refer to the temple in Jerusalem. How should we?
Why did the Samaritan woman use the term, Messiah, in John 4:25?
What did Jesus mean in John 4:22, ὑμεῖς προσκυνεῖτε ὃ οὐκ οἴδατε?

You worship what you do not know; we worship what we know, for salvation is from the Jews.
(John 4:22, ESV)

Jesus, the Messiah, who brought salvation, available to the world, was a Jew, from the linage of David.  By saying this Jesus also said the rest of the Tanakh (the prophets and the writtings), not just the Torah (5 books of the Law) were valid scriptures.  The Samaritans only accepted the Torah as authoritative.

They said to the woman, "It is no longer because of what you said that we believe, for we have heard for ourselves, and we know that this is indeed the Savior of the world."
(John 4:42, ESV)

Commentaries

Salvation is from the Jews, He did not mean that all Jews were saved or were especially pious. "Salvation is from the Jews" in the sense that it is available through Jesus, who was born of the seed of Abraham.
--
Blum, E. A. (1985). John. In J. F. Walvoord & R. B. Zuck (Eds.), The Bible Knowledge Commentary: An Exposition of the Scriptures (Vol. 2, p. 286). Wheaton, IL: Victor Books.

For salvation is from the Jews (ὁτι ἡ σωτηρια ἐκ των Ἰουδαιων ἐστιν [hoti hē sōtēria ek tōn Ioudaiōn estin]). "The salvation," the Messianic salvation which had long been the hope and guiding star of the chosen people (Luke 1:69, 71, 77; Acts 13:26, 47). It was for the whole world (John 3:17), but it comes "out of" (ἐκ [ek]) the Jews. This tremendous fact should never be forgotten, however unworthy the Jews may have proved of their privilege. The Messiah, God's Son, was a Jew.
--
Robertson, A. T. (1933). Word Pictures in the New Testament (John 4:22). Nashville, TN: Broadman Press.

For salvation is from the Jews.—[ἐστίν, the present, not ἕσται, for salvation was already at hand in the person of the Saviour.—P. S.] Σωτηρία: (1) Chrysostom, et al.: All benefits of salvation; (2) Erasmus: The prophetic knowledge of salvation; (3) The true Jews worship the God of continuous revelation. The proof of this lies in the fact that salvation breaks forth out of Judaism (Leben Jesu, II. p. 533). Similarly Tholuck, Meyer. In ἐκ τῶν (see Rom. 9:4 ff) are intimated (1) the personal issuing of salvation out of Judaism, (2) its inward connection with Judaism, (3) its distinction from it. The expression is an evidence that John names the Jews not in a hostile sense alone.

[By this declaration Christ sets the seal of His authority on the Jewish religion as a divine revelation to prepare mankind for His coming, and sets aside all other religions as false, or at best as groping in the dark after "the unknown God." This preparation by law, types, and prophecy, running back in unbroken succession to Abraham, and even to the very gates of paradise lost (Gen. 3:14), forms one of the most convincing evidences of Christianity, as the final and perfect religion of mankind—P. S.]
--
Lange, J. P., & Schaff, P. (2008). A commentary on the Holy Scriptures: John (p. 161). Bellingham, WA: Logos Bible Software.

4:22. Jesus is not neutral; he accepts the correctness of the Jewish position, although he does not allow that to remain as an ultimate barrier to racial reconciliation (4:23). In a Gospel addressing Jewish Christians rejected by their synagogues (see the introduction), this point is significant.
--
Keener, C. S. (1993). The IVP Bible background commentary: New Testament (Jn 4:22). Downers Grove, IL: InterVarsity Press.

for salvation is from (ἐκ) the Jews. Literally he says the salvation; i.e., that specific rescue from the guilt, pollution, and punishment of sin, and that sum-total of every spiritual endowment, which God grants to his people on the basis of the redemptive work of his Son. That this salvation proceeds from the Jews is clear from Ps. 147:19, 20; Isa. 2:3; Amos 3:2; Mic. 4:1, 2; Rom. 3:1, 2; 9:3–5; 9:18.
--
Hendriksen, W., & Kistemaker, S. J. (1953–2001). Exposition of the Gospel According to John (Vol. 1, pp. 166–167). Grand Rapids: Baker Book House.
Answer: What did Jesus mean when he said salvation is from the Jews?
1/  The Jews' were entrusted with the words of God that could lead to salvation. That is why Jesus  could say to the Samaritan woman;

John 4:22  NET "You people worship what you do not know. We worship
what we know because salvation is from the Jews."

Romans 3:1-2 NASB

Then what [a]advantage does the Jew have? Or what is the benefit of
circumcision? 2 Great in every respect. First, that they were
entrusted with the actual words of God.

2/The Messiah would come from God's chosen people, the Jews, and anyone wanting to serve God had to associate with God's people.
Genesis 22:18 NASB

18 And in your seed all the nations of the earth shall be blessed,
because you have obeyed My voice."
Answer: The answer to this question is probably answered by Paul in Rom 9:5, 6 -

the people of Israel.

Theirs is the adoption as sons;
theirs the divine glory
and the covenants;
theirs the giving of the law,
the temple worship,
and the promises.
Theirs are the patriarchs,
and from them proceeds the human descent of Christ ...

Paul might have also added that from the Jews also came the inspired sacred Scriptures.
Little wonder that Jesus could say, "salvation is of the Jews" (John 4:22).  He also said:

John 14:6 - Jesus answered, "I am the way and the truth and the life. No one comes to the Father except through Me.

Peter stated the same truth this way:

Acts 4:11, 12 - This Jesus is 'the stone you builders rejected, which has become the cornerstone.' Salvation exists in no one else, for there is no other name under heaven given to men by which we must be saved."

Ellicott adds this:

(22) For salvation is of the Jews.—This verse has sorely tried
critics who seek to construct the Gospel out of their judgments of
what it should be. It can be no difficulty to those who seek to form
their judgments from the Gospel as it is. Assume that the Gospel
belongs to the Greek thought of the close of the second century, and
the verse must be omitted, though it is certainly part of the original
text; accept the Gospel as belonging to the Hebrew thought of the
first century, and this touch of Jewish theology is in entire harmony
with it. The contrast between the Samaritan and the Jewish worship lay
in its history, its state at that time, and its rejection of the
fuller teaching of the prophetical books of the Old Testament. "In
every way the Jews had much advantage, but chiefly that unto them were
committed the oracles of God." Little as they knew the treasure they
possessed, they were the guardians of spiritual truth for the world,
and in a sense deeper than they could fathom, "salvation was of the
Jews." (Comp. Romans 3:2; Romans 9:4-5, Notes; Isaiah 2:3; Micah 4:2.)

Similarly, Benson:

For salvation is of the Jews — All the prophets spoke of the Saviour
as one that should come out of the Jewish nation, and that through him
the knowledge of the true God, and of the true way of worshipping and
serving him, should be communicated to the rest of mankind. For, as
the author of salvation came of the Jews, appeared among them, and was
sent first to bless them, affording them, in an extraordinary way, the
means of salvation; so the word of salvation was of them, and was
delivered to them, to be derived from them to other nations. This was
a sure guide to them in their worship, and they who followed it knew
what they worshipped. As they, therefore, were thus privileged and
advanced, it was presumption for the Samaritans to vie with them.
Answer: What did Jesus mean when he said salvation is from the Jews?
I understand this from the point of view of contrast.
The setup of this contrast started in
John 4:

9The Samaritan woman said to him, "You are a Jew and I am a Samaritan woman. How can you ask me for a drink?" (For Jews do not associate with Samaritans. )

First, the contrast was between Jews and Samaritans.

22 You Samaritans worship what you do not know; we [Jews] worship what we do know, for salvation is from the Jews.

This same contrast was repeated.

23 Yet a time is coming and has now come when the true worshipers will worship the Father in the Spirit and in truth, for they are the kind of worshipers the Father seeks. 24God is spirit, and his worshipers must worship in the Spirit and in truth."

Now Jesus broadened the contrast to Jews vs Gentiles.
Peter echoed this in Acts 4:

12 Salvation is found in no one else, for there is no other name under heaven given to mankind by which we must be saved."

Among all mankind, salvation was from the Jewish Messiah, Jesus Christ.
What did Jesus mean with his statement "salvation is from the Jews"?
Salvation is not from the Gentiles.
Answer: Like the USA, Korea, Ireland and other countries, The United Kingdom of Israel was divided up into a Northern Kingdom and a Southern Kingdom. Samaria was the capitol of the Northern Kingdom aka Israel, and Jerusalem was the capitol of the Southern Kingdom aka Judah. The word translated "Jews" in the scriptures refers to the Judeans.
The Northern Kingdom fell into Ba'al worship, so the LORD eliminated them from the Sinai covenant. However, the Southern Kingdom, Judah, whose capital was Jerusalem, remained in covenant. Jesus alludes to this:

[Hos 1:3-7 KJV] [3] So he went and took Gomer the daughter of Diblaim; which conceived, and bare him a son. [4] And the LORD said unto him, Call his name Jezreel; for yet a little [while], and I will avenge the blood of Jezreel upon the house of Jehu, and will cause to cease the kingdom of the house of Israel. [5] And it shall come to pass at that day, that I will break the bow of Israel in the valley of Jezreel. [6] And she conceived again, and bare a daughter. And [God] said unto him, Call her name Loruhamah: for I will no more have mercy upon the house of Israel; but I will utterly take them away. [7] But I will have mercy upon the house of Judah, and will save them by the LORD their God, and will not save them by bow, nor by sword, nor by battle, by horses, nor by horsemen.

So Israel is the vessel of wrath and Judah will be miraculously saved. However, Ezekiel promised a day would come when the Messiah would come and seek out these Lost Sheep of the House of Israel and bring them into the Promised Land, resurrect them and reunite them with Judah:

[Eze 37:11-23 NASB95] [11] Then He said to me, "Son of man, these bones are the whole house of Israel; behold, they say, 'Our bones are dried up and our hope has perished. We are completely cut off.' [12] "Therefore prophesy and say to them, 'Thus says the Lord GOD, "Behold, I will open your graves and cause you to come up out of your graves, My people; and I will bring you into the land of Israel. [13] "Then you will know that I am the LORD, when I have opened your graves and caused you to come up out of your graves, My people. [14] "I will put My Spirit within you and you will come to life, and I will place you on your own land. Then you will know that I, the LORD, have spoken and done it," declares the LORD.'" [15] The word of the LORD came again to me saying, [16] "And you, son of man, take for yourself one stick and write on it, 'For Judah and for the sons of Israel, his companions'; then take another stick and write on it, 'For Joseph, the stick of Ephraim and all the house of Israel, his companions.' [17] "Then join them for yourself one to another into one stick, that they may become one in your hand. [18] "When the sons of your people speak to you saying, 'Will you not declare to us what you mean by these?' [19] say to them, 'Thus says the Lord GOD, "Behold, I will take the stick of Joseph, which is in the hand of Ephraim, and the tribes of Israel, his companions; and I will put them with it, with the stick of Judah, and make them one stick, and they will be one in My hand."' [20] "The sticks on which you write will be in your hand before their eyes. [21] "Say to them, 'Thus says the Lord GOD, "Behold, I will take the sons of Israel from among the nations where they have gone, and I will gather them from every side and bring them into their own land; [22] and I will make them one nation in the land, on the mountains of Israel; and one king will be king for all of them; and they will no longer be two nations and no longer be divided into two kingdoms. [23] "They will no longer defile themselves with their idols, or with their detestable things, or with any of their transgressions; but I will deliver them from all their dwelling places in which they have sinned, and will cleanse them. And they will be My people, and I will be their God.

But only a divinely selected remnant would return of the Northern Kingdom:

[1Ki 19:17-18 NASB95] [17] "It shall come about, the one who escapes from the sword of Hazael, Jehu shall put to death, and the one who escapes from the sword of Jehu, Elisha shall put to death. [18] "Yet I will leave 7,000 in Israel, all the knees that have not bowed to Baal and every mouth that has not kissed him."

[Rom 11:1-10 NASB95] 1 I say then, God has not rejected His people, has He? May it never be! For I too am an Israelite, a descendant of Abraham, of the tribe of Benjamin. [2] God has not rejected His people whom He foreknew. Or do you not know what the Scripture says in [the passage about] Elijah, how he pleads with God against Israel? [3] "Lord, THEY HAVE KILLED YOUR PROPHETS, THEY HAVE TORN DOWN YOUR ALTARS, AND I ALONE AM LEFT, AND THEY ARE SEEKING MY LIFE." [4] But what is the divine response to him? "I HAVE KEPT for Myself SEVEN THOUSAND MEN WHO HAVE NOT BOWED THE KNEE TO BAAL." [5] In the same way then, there has also come to be at the present time a remnant according to [God's] gracious choice. [6] But if it is by grace, it is no longer on the basis of works, otherwise grace is no longer grace. [7] What then? What Israel is seeking, it has not obtained, but those who were chosen obtained it, and the rest were hardened; [8] just as it is written, "GOD GAVE THEM A SPIRIT OF STUPOR, EYES TO SEE NOT AND EARS TO HEAR NOT, DOWN TO THIS VERY DAY." [9] And David says, "LET THEIR TABLE BECOME A SNARE AND A TRAP, AND A STUMBLING BLOCK AND A RETRIBUTION TO THEM. [10] "LET THEIR EYES BE DARKENED TO SEE NOT, AND BEND THEIR BACKS FOREVER."

So Israel 2.0 became God's People aka the Israel of God. They became the foundation of the Kingdom of God, the 144,000 while branches were broken off of the Judah tree, to make way for them:

[Rev 7:4-8 NASB95] [4] And I heard the number of those who were sealed, one hundred and forty-four thousand sealed from every tribe of the sons of Israel: [5] from the tribe of Judah, twelve thousand [were] sealed, from the tribe of Reuben twelve thousand, from the tribe of Gad twelve thousand, [6] from the tribe of Asher twelve thousand, from the tribe of Naphtali twelve thousand, from the tribe of Manasseh twelve thousand, [7] from the tribe of Simeon twelve thousand, from the tribe of Levi twelve thousand, from the tribe of Issachar twelve thousand, [8] from the tribe of Zebulun twelve thousand, from the tribe of Joseph twelve thousand, from the tribe of Benjamin, twelve thousand [were] sealed.

So in the time before the death, resurrection and return of Christ to inflict the utter destruction and depopulation of Jerusalem, the capitol of the Southern Kingdom (Judah), Judah was covenant-Beloved, and so "the house of prayer for all nations."
However, in Paul's conversation with the Samaritan woman at the Jacob's well, Jesus says that the United Kingdom of God would be restored (which is called in English Bibles, "the regeneration," and for her, this was happening presently, because Christ was speaking to her:

[Jhn 11:19-26 NASB95] [19] and many of the Jews had come to Martha and Mary, to console them concerning [their] brother. [20] Martha therefore, when she heard that Jesus was coming, went to meet Him, but Mary stayed at the house. [21] Martha then said to Jesus, "Lord, if You had been here, my brother would not have died. [22] "Even now I know that whatever You ask of God, God will give You." [23] Jesus said to her, "Your brother will rise again." [24] Martha said to Him, "I know that he will rise again in the resurrection on the last day." [25] Jesus said to her, "I am the resurrection and the life; he who believes in Me will live even if he dies, [26] and everyone who lives and believes in Me will never die. Do you believe this?"

The sequence of birth pains -> birth is reversed, with birth pains (c. 70 AD/CE) would precede the birth of United Israel 2.0 aka The Israel of God.

[Mat 24:8 NET] [8] All these things are the beginning of birth pains.

[Mar 13:8 NET] [8] For nation will rise up in arms against nation, and kingdom against kingdom. There will be earthquakes in various places, and there will be famines. These are but the beginning of birth pains.

[Gal 4:27 NET] [27] For it is written: "Rejoice, O barren woman who does not bear children; break forth and shout, you who have no birth pains, because the children of the desolate woman are more numerous than those of the woman who has a husband."

[Jer 22:23 NET] [23] You may feel as secure as a bird nesting in the cedars of Lebanon. But oh how you will groan when the pains of judgment come on you. They will be like those of a woman giving birth to a baby.

[Rev 12:2 NET] [2] She was pregnant and was screaming in labor pains, struggling to give birth.

The background of all that is this:

[Isa 66:7-13 NKJV] [7] "Before she was in labor, she gave birth; Before her pain came, She delivered a male child. [8] Who has heard such a thing? Who has seen such things? Shall the earth be made to give birth in one day? [Or] shall a nation be born at once? For as soon as Zion was in labor, She gave birth to her children. [9] Shall I bring to the time of birth, and not cause delivery?" says the LORD. "Shall I who cause delivery shut up [the womb]?" says your God. [10] "Rejoice with Jerusalem, And be glad with her, all you who love her; Rejoice for joy with her, all you who mourn for her; [11] That you may feed and be satisfied With the consolation of her bosom, That you may drink deeply and be delighted With the abundance of her glory." [12] For thus says the LORD: "Behold, I will extend peace to her like a river, And the glory of the Gentiles like a flowing stream. Then you shall feed; On [her] sides shall you be carried, And be dandled on [her] knees. [13] As one whom his mother comforts, So I will comfort you; And you shall be comforted in Jerusalem."

It would take a few books to be able to explain all of this, so I'll avoid TLDR and just leave you with this:

[Mat 19:28 NKJV] [28] So Jesus said to them, "Assuredly I say to you, that in the regeneration, when the Son of Man sits on the throne of His glory, you who have followed Me will also sit on twelve thrones, judging the twelve tribes of Israel.

Point to ponder: When did Jesus sit upon the shiny throne? Upon his ascension? When did he return?:

[1Co 15:24-28 NKJV] [24] Then [comes] the end, when He delivers the kingdom to God the Father, when He puts an end to all rule and all authority and power. [25] For He must reign till He has put all enemies under His feet. [26] The last enemy [that] will be destroyed [is] death. [27] For "He has put all things under His feet." But when He says "all things are put under [Him]," [it is] evident that He who put all things under Him is excepted. [28] Now when all things are made subject to Him, then the Son Himself will also be subject to Him who put all things under Him, that God may be all in all.

[Mat 16:28 NKJV] [28] "Assuredly, I say to you, there are some standing here who shall not taste death till they see the Son of Man coming in His kingdom."

It was left to Paul to gather the gentiles.


HP Stream 7 originally runs Windows - Can it run Android viably?

Question: I have an HP Stream 7 that I'm not using here (since I've bought my Asus T100), and I was thinking about putting an Android to run, instead of the Windows OS. I know that is possible, but my question is: is it viable? Has someone already tested this using the same model? Does it have any problems with drivers, or something that Android does not recognize? If it works, I'll definitely give it a shot.
Answer: After a little bit of work, I was able to run an Android live version at the HP Stream 7. Unfortunately, it's a little bit buggy, mainly because there is no drivers available for the device. I will make some researches on, to see what I can find. Thanks for the answer
Answer: Drivers are the largest issue, trying this.  LUbuntu (ubuntu lite) or XUbuntu (runs x11 gui manager, even lighter) BUT, you'll need to know the CPU type on your tablet.  Most all 'nix' software is ported to run on x386 (aka Intel Atom) processor.  The ARM architecture is more of a challenge. NOOBS the standard Raspberry Pi image, gives you a 50/50 chance.!   IMHO  Some of the ARM xuntu distributions would probably run fine.  You'll have to read on those OS and Platforms.  The new Allwinner Tech ARM CPU's are forcing their way into  being the ARM standard. you'll then have to worry about drivers, & not be afraid of downloading and installing APK files... good luck, keep us posted.  I have a couple allwinner white box tablets, that bricked themselves, it would be nice to have them run "something" , even if it's a remote video cam to watch the kid go in/out of the house!
Comment: Maye I can try Live USB the Ubuntu. I tried the Android version at the Stream 7, but I had problems with a couple of things. Screen rotation wasn't working, and also bluetooth, and so on. Maybe it was due to lack of drivers, indeed. But I'll hear you, and try to LiveUSB the LUbuntu on it!
Answer: It's months later, I can add a new ponderance to your problem and the solution.
All Android OS on any device is really a Java Virtual Machine.
Download for Linux, Windows, Mac.... the Android SDK  you can build from almost any version, to almost any hardware.  You will have to read, read, read.
Answer: no you cant, its just impossible. Drivers are a huge problem as android os needs not available on the stream 7
Comment: Although this answer may be correct, a proper answer should include detailed information and verifiable links to references, otherwise it just sounds like opinion. I suggest reading this page: https://android.stackexchange.com/help/how-to-answer to help you improve your answer and future ones.


Alternative to using ArcGIS Online Geocoding

Question: I have 1.4 million addresses that I need to batch geocode. I can't find a free service to do so. Does anyone know of something out there that I can use? Oh, the service needs to be were I can upload a file in a .txt file formate, not a copy and paste. Copy and paste services crash the 661 mb size file.
Answer: You could try Nominatim from OpenStreetMap:

Nominatim (from the Latin, 'by name') is a tool to search OSM data by name and address and to generate synthetic addresses of OSM points (reverse geocoding). It can be found at http://nominatim.openstreetmap.org

You may need to write the wrapper functionality to allow uploading of a text file.
Answer: You could try MMQGIS plugin in QGIS. It uses Google API for geo-coding and reverse geo-coding.
http://plugins.qgis.org/plugins/mmqgis/
Go to MMQGIS tab> Transfer > Geocode CSV from Google.
It takes CSV file as input but output geocoded file and not-found-addresses file in case of no address found on google map. Make sure your CSV is in the right format for this plugin.
Answer: SmartyStreets has a Bulk Address Validation Tool for Lists service that is designed to do exactly what you're looking for: You upload a list (.csv, .txt, or .xls) and a few minutes later you download the output files, which give 45 data points, including geocode data, for each address.
Our pricing is very competitive, with no minimum purchase price, and if you're a startup or a nonprofit, then you can probably get our service for free.


How I'll Put fb like plugin into Drupal homepage?

Question: I want to add a facebook like social plugin into my Drupal
website. But I'am unable to find the file in which I'll
write the plugin code. Please help me.
Answer: You don't need to add any code there is already a module for this http://drupal.org/project/fblikebutton
Simply install the module in your drupal instance.
Cheers,
Vishal
Answer: In page.tpl.php between  insert this analog with your appcode from facebook

And in place for Like button insert/ For example inser this in block with PHP filter
<div class="fb-like" data-href="http://yoursite.com/<? echo $_SERVER["REQUEST_URI"];  ?>" data-send="false" data-width="450" data-show-faces="false" data-colorscheme="dark">

Answer: FB like button and like box are different.
Like button is to "like" a single page and it comes with an optional inline counter. But Like box is to show who other likes a particular Facebook page. It's appearing as a box.
You can grab the like box code from your facebook page admin UI and put it in a custom block.
http://drupal.org/project/fb_social is a good module that gives a lot of facebook elements.
Facebook like button code - https://developers.facebook.com/docs/reference/plugins/like/
Facebook like box code - https://developers.facebook.com/docs/reference/plugins/like-box/
Add a fb like button - http://drupal.org/project/fblikebutton (or edit node.tpl.php), http://drupal.org/project/sociallinks
Add fb like box - Custom block, http://drupal.org/project/fb_social or page.tpl.php (I recommend to not do this unless this you have a very good understanding in theming. Less configurable)
Like box should be a module. Like button is a node-element.


Using same algorithm for signing and encrypting a message

Question: If we use the same algorithm to encrypt and sign a message, what can happen if the message is intercepted and read by a third party?
Comment: There is no such same algorithm. Only RSA uses the same trapdoor function to implement encryption, decryption, signature, and sign. However, the padding schemes are completely different RSA-OAEP for encryption and RSA-PSS for signature.
Comment: It does not matter, as long as it is not a weak or obsolete algorithm being used.
Comment: It is okay to use RSA-based signatures and RSA-based encryption, but do not try to use the same key for both algorithms.
Answer: Although the names of the algorithms are the same, they are actually a little different when used for signing vs when used for encryption. The only thing similarity the two algorithms have is that they both use the same trapdoor permutation, conveniently called RSA. The difference is both in where certain variables come from, and the use of padding, which turns the insecure function into a cryptographically secure and useful algorithm. Encryption often uses RSA-OAEP, whereas signing uses RSA-PSS.
So even if you are using RSA/RSA for encryption and signing, an attacker who intercepts the message will be able to neither decrypt it nor forge valid ciphertext without first obtaining the relevant private key.


Did Galileo intuit Newtons Second Law and Law of Gravitation?

Question: If Galileo had no idea of Newton's Second Law or his Law of Gravitation, how did he figure out that objects of dissimilar mass fall at the same rate of acceleration if their initial conditions are the same? Only by experiment?
Answer: Galileo argued that earth gravity causes uniform acceleration. That is, Galileo argued: as an object is released to falling its velocity starts at zero, and then increases proportional with time. In other words: in double the time you get double the velocity.

My knowledge of the history of this is not sufficient, but by the looks of it Galileo did not press to generalize to the effect of any force.
In retrospect: it wasn't even necessary for galileo to assume that gravity is a force. To argue what Galileo wanted to argue it was not necessary to address the general concept of force.
Galileo argued the point that he needed to argue: that earth gravity causes uniform acceleration.

As to objects of dissimilar mass falling at the same rate. For that Galileo argued in the form of a thought demonstration, a thought demonstration that draws on everyday experience.
You can tie two bricks together with a string. Will that package accelerate in the same way as the individual bricks? If you believe the package will accelerate faster, then try it again, this time with more slack in the string. With thought demonstrations like that, appealing to everyday experience, Galileo argued that independent of the bulk of an object gravity always causes the same acceleration.
Comment: Most historians do not believe that Galileo carried out this experiment. Therefore, unless he had some mathematical insight--after all, he was a highly accomplished mathematician and physicist--he had to come to this conclusion by an argument based on logic--your idea of a thought experiment--not nearly as elegant as the proof using Newton's Second Law in combination with his Law of Gravity.


How to find out what programming language a website is built in?

Question: I think that it's fundamental for security testers to gather information about how a web application works and eventually what language it's written in.
I know that URL extensions, HTTP headers, session cookies, HTML comments and style-sheets may reveal some information but it's still hard and not assured.
So I was wondering: is there a way to determine what technology and framework are behind a website ?
Comment: My tomcat server returns "CERN httpd" just to mess with people
Comment: @HagenvonEitzen If HTML had been a programming language it would have been named HTPL rather than HTML.
Comment: Try www.builtwith.com
Comment: `I think that it's fundamental for security testers to gather information about how a web application works and what language it's written in.`  I think that, if even a security tester can't figure out what language the site is built in, that makes it more secure because then no one will know which exploits to try. (Yes, there are occasionally valid use cases for security through obscurity.)
Comment: @MasonWheeler: figuring out what language the site is built in will only determine which exploits *not* to try. That won't make the site more secure.
Comment: My first guess would be HTML
Comment: @BenoitEsnard well, if an attacker uses it to determine which exploits *not* to try, then it would be a security improvement if a site successfully misleads the attacker into thinking it's something different and thus the attacker skips trying the "proper" exploits.
Comment: I use to be satisfied by just checking .php or .aspx to identify if website is on PHP or on ASP.NET webforms. Now a days, with URL routing and MVC framework it is quite hard for me to differentiate. :p thanks for the question.
Answer: There's no way to be 100% sure if you don't have access to the server, so it's about guessing. Here are some clues:

File extensions: login.php is most likely a PHP script.
HTTP headers: they may leak some information about the language which is running on the server, and some additional details like the version: X-Powered-By: PHP/7.0.0 means that the page was rendered by PHP.
HTTP Parameter Pollution: if you managed to guess which server is running, you can refine the guess.
Language limits: maximum post data, maximum number variable in GET and POST data, etc. It may be useful if the webmaster kept the default values.
Specific input: for example, PHP had some easter eggs.
Errors: triggering errors may also leak the language. Warning: Division by zero in /var/www/html/index.php on line 3 is PHP, for example.
File uploads: libraries may add metadata if the file is being modified server-side. For example, most sites resize users' avatars, and checking for EXIF data will leak CREATOR: gd-jpeg v1.0 (using IJG JPEG v90), default quality, which may help to guess which language is used.
Default filenames: Check if / and /index.php are the same page.
Exploits: reading a backup file, or executing arbitrary code on the server.
Open source: the website may have been open-sourced and is available somewhere on Internet.
About page: the webmaster may have thanked the language community in a "FAQ" or "About" page.
Jobs page: the development team may be recruiting, and they may have detailed the technologies they're using.
Social Engineering: ask the webmaster!
Public profiles: if you know who is working on the website (check LinkedIn and /humans.txt), you can check their public repos or their skills on online profiles (GitHub, LinkedIn, Twitter, ...).

You may also want to know if the website is built with a framework or a CMS, since this will give information about the language used:

URLs: directories and pages are specific to certain CMS. For example, if some resources are located in the /wp-content/ directory, it means that WordPress have been used.
Session cookies: name and format.
CSRF tokens: name and format.
Rendered HTML: for example: meta tags order, comments.

Note that all information coming from the server may be altered to trick you. You should always try to use multiple sources to validate your guess.
Comment: Just a note: just because the http headers *say* they're powered by php, doesn't mean the site actually is. Although this example is more about the server platform, I know of a guy who would make his nginx server return Server: Microsoft-IIS/5.0 with every request so he could trick attackers into using the wrong attacks against the server. "It's too easy!" ~ *the attacker*. You're right about that! (This just goes to show that you can't trust headers)
Comment: You forgot one of the simplest - looking at the jobs page. :)
Comment: You forget to mention some example that are from Java which use generally a cookie JSESSIONID for their session management. Login URL can betray unlerlying technology too, spring default URL for instance. Those example are for java but are surely true from some others
Comment: If there's a hidden field named "__VIEWSTATE", and/or if the buttons say "href=javascript:__doPostBack" it's likely asp.net. Off the top of my head I can't think of comparable "signatures" in other platforms, but, etc.
Comment: Another good one is checking the source to see if there are tell-tale signs of the use of some templating engine specific to a language.
Comment: @AhmedJerbi: I've added more techniques.
Comment: Nitpick: the first 9 will really only tell you what language was used to *deploy* the site, not to *build* it. E.g., if you determine that the site was deployed on a JVM, that doesn't tell you much, there are over 400 languages with implementations for the JVM, the site may have been built in Scala, Groovy, Clojure (which also has implementations for the CLI and ECMAScript), Fantom (ditto), Ruby (JRuby), Python (Jython), PHP (IBM P8, Quercus), ECMAScript (Mozilla Rhino, Oracle Nashorn, dyn.js). The same applies to the CLI (IronPython, IronRuby, IronJS, …). There are also many compilers that …
Comment: I liked the Parameter Pollution technique  .. I'm sure that there are many more ways though
Comment: @Walfrat: I've just detailed the CMS / framework part!
Comment: @Benoit: thank you ..  Many docs to read for the weekend :-)
Comment: … target PHP: haXe, Hack, Wasabi, …
Comment: @mowwwalker: i've added that sign under the "rendered HTML" part. I'm not sure if you were thinking about another sign though, so let me know if I missed something!
Comment: How about humans.txt?
Comment: Or maybe I'm trolling you. /cgi-bin/postcomment.exe turns out to be a ksh script.
Answer: For guessing the programming language, you can follow the three steps approach detailed below:
STEP 1 - Search evidences on the site itself
Manually...

Search on a site page at the bottom for phrases like:
-> "Powered by XXX"
-> "Proudly Powered by XXX"
-> "Running on XXX"
-> ...
Search on the site if it will attend any conference where they could talk about the website from a technical point of view

...or with the help of a tool

Read the HTML code downloaded by your browser
Fire up the Network Tab in developer toolbar and study the exchanges made between the browser and the server.
Search for some known hidden page:
wget -head http://the-site.com/private/admin
If you get 200, the site may be running on a plublicly (free, paid etc) available software.

STEP 2 - Search evidences on the web
Ask search engines for front-end errors
You can look for some errors produced by the website.

Some keywords to type in a search engine:

Error 500 site:the-site.com
Exception site:the-site.com
...
<what ever> site:the-site.com
=> You can simply replace "<what ever>" with some known error message produced by the various web technologies.

Ask search engines for back-end errors
You can even guess the technologies used in the backend:

ORA-12170 site:the-site.com
=> If you find something, the site may be using Oracle in its backend part.

Ask search engines for website competitors

Find what technology is popular in the website industry
Find what technology competitors are using
Find comparisons of the site with other competitors.
Those comparisons may talk about technologies in use

Technology survey sites
Those sites can provide great info to the the site you target. They may have already done some part of the job for you.

http://w3techs.com/sites
=> Enter the url of the site you're targetting and see what technologies (client or server side) have been detected.
Note that the site must be in the top 1M Alexa ranking.
http://stackshare.io/search/q=<keyword>
=> <keyword> can be anything company name, website name, etc

STEP 3 - Analyze your results
The evidences you have found in step 1 may be wrong because the site owner can alter them. Try to find contradictions between those evidences. Eliminate contradictional evidences.
Merge the evidences in step 2 between the various sources and yours. Again eliminate contradictional evidences.
Resume all your findings in a table like the one below.
+-------------+-----------+------------------+    ...   +----------+-------+--------+
| EVIDENCES   |  ON SITE  |  Search Engine 1              SOURCE n   SCORE   PCT (%)
+-------------+------------------------------+    ...   +----------+-------+--------+
|    PHP 7    |     X     |       X          |                X    |   3   |  300/n
+-------------+------------------------------+    ...   +----------+-------+--------+
|  Wordpress  |           |       X          |                X    |   2   |  200/n
+-------------+------------------------------+    ...   +----------+-------+--------+
     ...
+-------------+------------------------------+    ...   +----------+-------+--------+
|  EVIDENCE m |           |                  |                     |       | (100*SCORE)/n
+-------------+------------------------------+    ...   +----------+-------+--------+

Finally, you will be able to say "I'm confident at XX% that this site runs on YY (EVIDENCE i)".
Comment: This looks like a useful step by step guide, but it's probably a bad idea to present the arbitrary confidence score as a percentage. Even if a server gets a perfect score it could very well be a carefully assembled honeypot, so you shouldn't say you are a 100% confident that it isn't.
Comment: @AugustJanse How sould the arbitrary confidence score be presented ?
Comment: Something like "I conclude that this site runs on YY with a confidence score of XX" perhaps? The problem is that the percentage looks a bit too much like a probability.
Answer: It's simple. Add Wapplyzer extension available for Chrome as well as Firefox.
It tells about programming language, server, analytics tool or about CMS & Frameworks on which website is built.
Give it a try, you will love it.
Comment: Social Engineering: ask how to identify the software used to serve web pages on StackExchange and wait for people to tell what their site runs on. Thank you, @BradMetcalf...
Comment: I don't think it can be considered accurate. We purposely fake our sent headers to return IIS. Have a wp-admin.php even though we don't use Wordpress. And several other honey pots. Our site is actually a Node.js application that returns static content.
Comment: That seems good .. but is it reliable and accurate?
Comment: @Ahmed it works by [scanning](https://wappalyzer.com/suggestions) the HTML, headers, URL and JavaScript variables on a page. It's only as good as the rulesets used for detection of course, but I've found it to be right almost always. (But, of course, any web page can be set up to pretend to be running something it isn't.)
Comment: Yes, its very much accurate. I'm using it from last 4 years and even on my own developed websites. Its always accurate.
Comment: I just downloaded it as it is accurate as it can be.  Obviously it can't tell if the headers are being spoofed or not.
Answer: Besides the Wappalizer browser extension, there are several sites that detect what technologies power a given website:

http://builtwith.com/
http://onlinewebtool.com/cmsdetector.php - for CMS detection
http://guess.scritch.org/ - Detect CMS, web framework
Answer: The answer is that you can never "Be assured". Whilst 99.9% of the time the highly up voted answers will find the "tells" of the framework behind the site but it's never a certainty.
Basically your browser receives  the end results of  the codes  processing. (html, CSS and JavaScript ) Between you and the code itself sits a webserver (nginx, Apache etc) and potentially a load balancer and a CDN. Because your not interacting directly there is no way for certainty.
If a website is serving content from wp-uploads/   It's a safe bet that it's running Wordpress but it's not a certainty. Perhaps the site was using Wordpress but when it was  migrated to something else the  wp-uploads/ path was kept to avoid breaking links and bookmarks.
Answer: Sometimes you can know, sometimes you cannot.
If the HTML is generated on the client-side, then you can easily tell which language by looking at the source in your web browser.  These languages include: ruby on rails, javascript, java, etc.  On the client-side the source is open to the user, and it must be honest about which technology it is.
If the HTML is generated on the server-side you may not know which programming language generated it.  These languages include: PHP, C++, and many other languages.  On the server-side, for as many ways as you can think of to guess which language it is, there are just as many ways to for the technology to hide itself.
Suppose you are a web administrator that wants to hide the server-side technology.  Pick one of the techniques listed in another question for attempting to identify the language.  For example, the *.php extension for a file.  Now, configure your web server to execute C code from a file with a *.php extension.  Your users will have no way to view the source (since both languages are equally capable of producing the same output, by Turing completeness), but they will be misled into thinking you are running PHP.
Why would someone want to obfuscate the server-side choice of technology?  Because CGI languages have various vulnerabilities that are easier to target if the end-users know which of those languages you are using.  Misleading the users about which server-side technologies you are using is a very reasonable security measure.
Comment: I didn't downvote, but this answer neglects the numerous techniques available for determining the server-side language and tech.
Comment: For starters, Ruby on Rails and Java are perfectly capable of generating HTML entirely on the server side.


Mic-ing up solid electric guitar

Question: I'm trying to experiment with a technique that I believe was used by Buddy Holly and perhaps other guitarists. That is mixing the guitar signal with a microphone signal from the guitar being recorded acoustically. With an admittedly crummy karaoke mic the sound is at a low level and a bit noisy when boosted.  Where is the best place to position the mic to get maximum signal (whilst still being practical to play - given I'm not going to play beyond the 12th fret)?
Comment: At or above the 12th fret, pointing towards your strumming hand will get you closest & pointing in the right direction, with least chance of hitting it.
Comment: I've read a few apocryphal tales that the very quiet beginning of "Wish You Were Here" was an electric 12 string, intentionally unplugged. In any case, I think a better quality mic placed a few feet away will allow a better overall sound and easier playing access than a very low output one up close. I wouldn't worry about hand movement in front of the strings; in practice any variation might add to the rhythm in useful ways.
Comment: Solid, Les Paul Studio
Comment: @Andy, I'm gonna presume you mean the song by Pink Floyd and not the one by Incubus.
Comment: @Dedwards yes you're right I meant the PF version :)
Answer: That's an interesting technique. I would presume that the optimal mic location would be smack dab in-between the neck and the neck pickup. You'll get a little bit of resonating from the body, and that creamy sweet spot on the strings.

Mic-ing up solid electric guitar


What would be the effect of an excess of up quarks on stellar formation?

Question: Suppose you had 80% up quarks, and only 20% down quarks. How would this affect stellar formation?
Comment: @DavidZaslavsky this looks like a legitimate question to me. It is not relevant to know what processes could potentially lead to such an unusual up/down quark ratio. But the expected answer can discuss what impacts the up/down quark ratio has on stellar formation. Such and similar questions (or Gedankenexperiments) are legitimate in the "real world" and discussed by serious physicists doing accepted main stream physics. I countervoted the undeserved downvote.
Comment: I'm not sure this question is really answerable in its current form. Why would there be 80% up quarks and 20% down quarks?
Comment: Can people please stop downvoting this legitimate question? The question is clear, if the reader does not understand it it is his own fault. The increase of very capricious downvotes on this site is distracting.
Comment: Thanks, Dilaton. It is a problem on all stackexchange sites.
Answer: It's really not clear what hypothetical limits you're imposing.  I take your question to mean that in the process of baryogenesis the various baryons like protons and neutrons highly favored up quarks (lots more protons than neutrons).  Remember, quarks are subject to confinement so other than a quark-gluon plasma, quarks are confined to baryons.
Since stellar formation depends on hydrogen and hydrogen formation depends on protons and electrons primarily, it's unlikely that there would be any meaningful impact.
Also, remember that free neutrons are unstable and will undergo beta decay and convert to protons.  If there is an excess of protons the reverse can happen via electron capture.
I'm pretty sure even if there were some wild physical law that forced there to always be a huge imbalance of up to down quarks there would still be enough hydrogen formation for stars to form.  It's not clear what this restriction would do to hydrogen to helium fusion though.
Comment: It is not in my area of expertise, I am an experimentalist, but my intuition is that  if there were an unbalanced number of  free quarks the universe would stop expanding at the time of baryogenesis, due to the infinite attractive force of the free quarks. They are free in the initial soup because of the dimensions and energy  and asymptotic freedom afaik.
Comment: Well this is certainly not my area of expertise either.  I assumed any unbalance in the quarks would pair up to form meson and baryons.  Without anti-quarks to pair up though I don't think mesons could form.  You may be right that with too many excess unpaired quarks would immediately stop inflation.


How to change iCloud email

Question: I want to delete my existing iCloud email address and replace it with a new one. My Apple ID is a hotmail address which I do not want to change. I have been getting too much rubbish on my iCloud email, so I just want to delete it and replace with a new one.
Answer: Go to appleid.apple.com and add/change your email address there. However, I think you cannot set another email address anymore as the default one, other then the @me.com and @icloud.com
Answer: Rather than change it, you could just redirect unwanted emails to a fake address, which would then bounce.
I don't know whether this makes them eventually give up sending it, but you never see it again, it's as though it never happened.
I started getting a lot of spam from some random online dating service which I dealt with in this manner.
Start at https://www.icloud.com/#mail & from the gear icon at the bottom select Rules...
Add the spam senders & redirect to something random & unlikely to exists - firstname.lastname@example.com etc

Bye bye spam.
Answer: Do you want to delete it and replace a new one?
This page is about your question. You mail is hotmail instead of @me.com, @icloud.com or @mac.com. (Apple provides these.)
So, you can see the middle part of this article about "the third party email", using ctrl+f to search "third party". You can know how to do it.
Change your Apple ID

How to change iCloud email


How to connect my docker image to my kubernetes cluster?

Question: I have a simple play project, and I created a docker image for it.
I created the image like:
in my circle.yml I added:
deployment:
  feature:
    branch: /.*/
    commands:
      - docker login -e firstname.lastname@example.com -u ${ART_USER} -p ${ART_KEY} crp-docker-docker-local.someartifactory.com
      - sbt -DBUILD_NUMBER="${CIRCLE_BUILD_NUM}" docker:publish

Now in my jfrog account I have the image name for this project, and in my controller.yml I added this specific image.
But now I have created kubernetes clusters with 4 minions machines and one master machine, and I want to know how do I connect this docker image to this cluster to run it?
thanksss
Answer: kubectl run <app name> --image=<image name from jfrog>
If you want to automatically fetch the image name and start the container, you can run a special container that will fetch the image names


Is it possible to georeference in CartoDB using just UK postal codes?

Question: Is it possible to georeference using just UK postal codes. I have the minimum free account and have had now luck with this. IF so should the postal codes be continuous strings with no gaps and is it correct to add in the free text box the country as "United Kingdom"?
Answer: Yes it is, simply follows the steps in this tutorial and you should get what you need. I tested it on a table I have stored using this postcode column and the co-ordinates were swiftly generated.
:
As you write in your question, I added 'United Kingdom' in the country field and it worked.