Why don't bluetooth headphones ever have analog microphone output?

Question: When using the "headset/hands-free" profile, which is required for bidirectional speaker/microphone usage, the quality of Bluetooth audio is absolutely terrible. All Bluetooth headphones that I could find don't have any other way to connect the microphone than via Bluetooth: although they come with an analog 3.5mm cord, it only has three rings, allowing for stereo audio and no microphone. Because enabling the microphone over Bluetooth makes both the audio input (to the headphones' speakers) and output (from the headphones' microphone) sound terrible, this is not ideal. Yet, I could not find any Bluetooth headphones that support any other method. Why is this?
Answer: Here's a few educated guesses.
Not much market demand.  People that want a wireless headset will buy a wireless headset.  Why put in a 1/8" audio input then?  Because it's cheap and easy to do.  If a 1/8" jack is so cheap then shouldn't a four connector TRRS jack that has the microphone output be cheap and easy too?  Not really, because there's more than one way to wire that jack.
https://en.wikipedia.org/wiki/Phone_connector_(audio)#TRRS_standards
If they wire it one way then half the market can't use the jack.  If they include an adapter to swap the mic/gnd contacts then it's not so cheap and easy.  Because a little adapter can be easily lost, assuming people read the instructions on when they are needed and when not, there would be a lot of returns and support calls.  There's apparently circuits that can detect mic from gnd and therefore maintain global compatibility without the easily lost adapter but that adds to the cost.
There's two fixes for this.  First is USB-C is making the 1/8" jack obsolete on most every portable device.  There's only one way to wire USB-C for stereo audio out and mono mic in, assuming people follow the spec, and so no more regional differences on how headsets are wired.  Second, Bluetooth is upgrading the connection bandwidth and digital audio codecs.  The microphone quality will be better with new Bluetooth 5.2 devices.  That's not helpful for your current phone but you were going to buy a new one next year anyway, right?
I'm still seeing far too many new Bluetooth headsets with micro-USB-B for charging and 1/8" jack for audio years after the spec to replace both with USB-C.  I would have bought a USB-C headset last summer if I could have found one when I needed it.  Maybe they will be more common when the headset I bought then dies.  I checked the specs on the headset and it says it can use a TRRS cable to plug into a phone, it doesn't say if the microphone would work if wired though.  I'm tempted to buy a cable to find out if it works.
Comment: @whoKnows  I did say it was a guess.  The lack of market demand still stands.  I don't know when this CTIA/OMTP battle was over but it seems recent enough that headset producers will be reluctant to pick one or the other and simply play it safer, and cheaper, by not bothering with a mic connection.  Expect the 1/8" jack to disappear from Bluetooth headsets rather than fix this lack of a mic connection, in place of the 1/8" jack will be USB-C and Bluetooth 5.2.
Comment: 10 years ago it may have been "half the market" that wouldn't be able to use the jack if it was wired one way or another, but nowadays devices have mostly standardized onto the left-right-ground-mic configuration.


In arcgis10.2, can I access arcobjects using python?

Question: I am using python in Arcgis 10.2, but it seems Python cannot meet all my developing demands, from the forum, others recommend to use python to access arc objects,but what they mentioned is the old version, so I want to confirm whether I can make it in 10.2, any extension needed? If can, I can use vb.net and c# right? Everybody has experience on it?
Comment: Sorry littleleaf, it looks like you've asked a duplicate question. Have a read of my answer anyway and consider taking up .net programming to meet your needs. It is good to have programming as well as scripting; use python for what it's good for and ArcObjects for what it does, it's good to have the choice!
Comment: Hi Michael, thanks for your clarification, may I confirm that ArcGIS 10.2 and above are the same as 10.1 when accessing arcobjects?
Comment: Each new version has it's own new things but all the previous are still there. 10.2 might prefer Studio Express 2013 but apart from that they're all the same. I still have code written in 9.0/9.1 that works in 10.2.2 though I'm in the process of upgrading them to 10.1.
Comment: Hi Michael, it seems the free visual studio express does not support at ArcGIS 10, I am still trying to find about the 10.2.
Comment: It does, I am using it at home (10.1). Arc 10.0 had a problem where even though it was on the list it still didn't detect it. see http://resources.arcgis.com/en/help/system-requirements/10.2/index.html#//01510000006n000000 (SDK requirements) ArcGis 10.2 supports **Visual Studio Express 2010 only** and 2012 in the professional (paid) versions.
Answer: In this post Combining MS Office with GIS Nathan W suggests that com objects can be accessed from python, after a little digging I found http://www.codeproject.com/Articles/73880/Using-COM-Objects-in-Scripting-Languages-Part-Py which suggests that this is indeed the case.
If you can get an answer from Nathan W he might be able to give you some specific guidance.
C# and VB.net are much better at getting to the insides of ArcMap/Catalog but be prepared for a lot of lines of code and a bit of a learning curve. In python a lot of the methods are very simplified, but as necessary they are rigid. Programming in .NET makes you do all the little steps that are done in python simplistically and gives you the option of changing how it does things to suit your purposes.
I tell people who come to me for a program: I could write it in python in half a day and it will take minutes to run, or I could write it in .net in a day and it will take seconds to run! There is much more to programming than scripting but the end result will run much faster and there is a limit to what is feasible in python.
I recommend visual studio express 2010 like the one found here (I do not endorse this link, but you can find it on google) for ArcGis 10.1, it requires registration to a MSN account but apart from that it's free for non-commercial applications; when it's installed go back to your ESRI install media and install the correct developer kit... It's not installed by default and until you install your programming language it wont know which one to install.
Once that's done start a new ArcMap/ArcCatalog addin following these steps. The developer help that's installed with the SDK is a real source of knowledge with interfaces, samples and relationships; it's not so friendly to start but once you get into it it's great!
If you run into any difficulty with starting out there are plenty of samples only a google away and you could post on GIS.SE.


Can i compare two fields in report?

Question: I need to compare if a certain date/time field is greater than/less than another date field.  Can this be done in a report without calculating the same using formula/boolean fields?
Answer: Don't think so. You'll need a formula field, either direct one or something set with a workflow (or Apex code of course). If that's not feasible and conditions will change often - VF page embedded on a dashboard might be the way to go?
All our filters (in WHERE clauses, reports, listviews etc) compare field to value, not field to field. There are exceptions like lookup filters but that's not helping much.
You won't be able to pull it off with a formula built in the report itself (it'd be interesting to say LastModifiedDate:MAX - Custom_Date_Field__c:MAX and use grouping by Id to have 1 record and thus cheat with this MAX clause). But date & datetime fields can't be used in summary formulas. More info in the summary formula help.
Comment: In formula field (on the object) they can be compared because it makes sense to say "point in time minus another point in time = 3 days 7 hours". Even then - you'll probably agree that calculation "date + another date" makes no sense. With report-level formulas it's even worse because they will show for many rows at the same time and on grand total level for example. "Max date" makes sense but for all the rest SF decided they won't expose date fields, period.
Comment: Sadly it's a quite common requirement, from reminder kind of reports "days till the contract will expire / has to be extended" to team performance "how long was the Case open". There's no nice way for these :/ There are workarounds through formula fields but as the link to help says - usage of any kind of formula field with IF etc will slow the report and of course you're wasting a field...
Comment: You're saying because it's a date/time field the two can't be compared?
Comment: All good points eyescream. I was thinking along the lines of adding a custom cross-block formula with a "days between" or "hours between" type of formula approach. Admittedly, I've never had the need to try it. Will add that to my "to try" list. ;)
Comment: Thanks eyescream. Learned something new today. The "how long was open" is exactly one of the things that came to mind because it's one of the metrics included as part of the tutorial in the Platform Fundamentals Workbook. They did a grtr than no days in their formula as I recall but also stored the actual days between Open and Close in a separate field.
Answer: Salesforce is coming with this new feature soon.
Refer for more details https://success.salesforce.com/ideaview?id=08730000000BrHAAA0

Can i compare two fields in report?


I am getting 'Username is longer then 16 characters' when attempting to log in to a Minecraft Server

Question: I have Minecraft, and when i try and join a server, it says my username is longer than 16 characters. I think it is trying to use my full email address. Is this the case? What else would cause this error, and what options do I have to try and resolve this?
Comment: **Is** your username longer than 16 chars?
Comment: Is this a problem join a *specific* server, or joining *any* server?
Answer: This (obviously) occurs when your username is longer than 16 characters....
And this means any character: Any letter, punctuation mark, number, or symbol.
So, If I did "MyUSERNAMEIS12345!!!!!!!" (24 characters), it would display the above-mentioned error.
Minecraft would never need your full email address while joining servers, so I don't suppose the problem is with that. Check your username length.
Comment: @aman207 - Doesn't make a difference. Minecraft checks your username (ign) not your email.
Comment: What if you merged your Minecraft account with your Mojang account? You need to use your email to log into Minecraft then.
Comment: @Titilolo3 As < said, when you login (I go through this every login) I input my email. When I play, my username is displayed, not my email.


Given $A$ a convex set of $\mathbb{R}^n$ such that $int(A) \neq \emptyset$, prove that $int(cl(A)) = int(A)$.

Question: I was given this problem and I'm struggling with the $int(cl(A)) \subseteq int(A)$ contention. The other contention is trivial and is true regardless of whether $A$ is convex (that is that the line segment between any two points $A$ is completely contained in A, or rather $\forall x, y \in A, 0 \leq \lambda \leq 1$ its $\lambda x + (1-\lambda)y \in A$). Furthermore, I was able to come up with an example where the equality is not true if $A$ is not convex (take $\mathbb{R}^n - \{(0,0)\}$ ). However I really don't know what to do after taking $x \in int(cl(A))$ and a ball of radius $\epsilon > 0$ such that $B_\epsilon(x)\subseteq cl(A)$. I don't know how to incorporate the convexity of $A$ into the proof, I've tried assuming there's a point in $B_\epsilon(x)$ that is not in $A$ to arrive at a contradiction, but there's just something I'm missing.
Answer: From Wikipedia, I present one of the versions of the Hahn-Banach Separation Theorem:

Let $X$ be a real locally convex topological vector space and let $A$ and $B$ be non-empty convex subsets. If $\operatorname{Int} A \neq \emptyset$ and $B\cap \operatorname {Int} A=\emptyset$ then there exists a continuous $\lambda \in X^*$ such that $\sup \lambda(A) \leq \inf \lambda (B)$ and $\lambda (a)<\inf \lambda (B)$  for all $a\in \operatorname {Int} A$ (such a $\lambda$ is necessarily non-zero).

Fix $a$ in the boundary of $A$, and let $B = \lbrace a \rbrace$. Then $B$ is convex, and $B\cap \operatorname {Int} A=\emptyset$. Apply the theorem to obtain some such $\lambda$. Choose an $x$ in the underlying space such that $\lambda(x) = 1$ (remember, $\lambda \neq 0$), and note that, for $\varepsilon > 0$,
$$\lambda(a + \varepsilon x) = \lambda(a) + \varepsilon > \lambda(a) = \inf \lambda(B) \ge \sup\lambda(A) = \sup \lambda(\overline{A}).$$
Therefore, $a + \varepsilon x \notin \overline{A}$. Note that, if $a \in \operatorname{Int} (\overline{A})$, this could not be true for sufficiently small $\varepsilon$. Hence, we have proven the contrapositive of what you want proven.
Answer: A definitive source is Rockafellar's "Convex Analysis". The result is Theorem 6.3 in said text.
(Well, Rockafellar deals with the relative closure & interior, but it amounts to the same thing if we restrict ourselves to $\operatorname{aff} A$.)
Since $A \subset \overline{A}$ we have $A^\circ \subset \overline{A}^\circ$.
For the other direction, the key result here is if $y \in \overline{A}$ and $x \in A^\circ$, then for
$\lambda \in [0,1)$, we have $(1-\lambda )x+ \lambda y \in A^\circ$ (Rockafellar, Theorem 6.1). I will give a proof of
this below.
Suppose $z \in \overline{A}^\circ$ and $x \in A^\circ$. Then for some $\mu>1$ sufficiently
close to one we have
$y=(1-\mu)x+\mu z \in \overline{A}^\circ \subset \overline{A}$ and
$z = {1 \over \mu} y + (1- {1 \over \mu})x$ so from above, $z \in A^\circ$, hence we
have the desired result.
Proof of Theorem 6.1: Rockafellar has a succinct proof, here is one with sequences.
Suppose $y \in \overline{A}$ and $x \in A^\circ$. There is some sequence $y_k \to y$
with $y_k \in A$.
Let $K = \cup_{\lambda \in [0,1)} B((1-\lambda)x + \lambda y, (1-\lambda) \epsilon)$, it is clear that this is open since it is the union of open sets. Furthermore,
it is clear that $y \in \overline{K}$. It remains to show that $K \subset A$ (and
so $K \subset A^\circ$).
Pick $z \in K$, then $z = (1-\lambda)x+\lambda y + (1-\lambda) \delta$, where $\lambda \in (0,1)$ and $\delta \in B(0, \epsilon)$.
If we let $\delta_k = { z - \lambda y_k \over 1 - \lambda} -x$, we see that $\delta_k \to \delta$, so for sufficiently large $k$, $\delta_k \in B(0,\epsilon)$ and since
$z = (1-\lambda)(x+\delta_k)+\lambda y_k$, we see that $z \in A$ and hence $z \in A^\circ$.
Comment: This is precisely what I was looking for, thanks a lot!


How to write an email for politely asking an schedule of 2nd round of interview

Question: I attended an interview on the 16th April 2016. I was informed that I was shortlisted for the second round of interviews. 15 days back I got an email saying that HR has not received any tentative schedule for an arrival from US, who will be taking the 2nd round of interviews and was told they will be updating me soon regarding the schedule and the interviewer details. But it's been 2 weeks; and still I got no schedule for the interview. Please let me know how to follow up and write an effective email to ask for the schedule.
Answer:
Hi XX,
I am writing to ask whether there are any updates on when the second
  interview will take place. I am very interested in the position and
  would love to move forward with your company.
Thanks for your time.
Sincerely, Altaf.

Key points:

Keep things short and direct.
Don't appear pushy or impatient.
Reiterate your interest.

Move on if you still don't hear from them. Ignoring you is very unprofessional.
Meanwhile, keep yourself busy by looking for other jobs as well. Keep your options open; don't pin all your hopes on one company. If you end up receiving multiple offers, your negotiating power will improve.


how to integrate InMobi in cocos2d game?

Question: Can i integrate InMobi in cocos2d game? I integrated InMobi in UI Game but i don't know how to integrate the InMobi in cocos2d game? Any one tell me if any tutorials.
Thanks.
Answer: I work for InMobi.  All of our iOS tutorials are available at
http://developer.inmobi.com/wiki/index.php?title=InMobi_SDK_3.7_for_iOS
There shouldn't be any problems integrating with Cocos2D


Change details view of iOS or Android without going back to UITableView

Question: We are redesigning our app and the current one you need to hit the back button to view all Divisions to get to a new Division Details page. We are looking for the best UI option to just change the division on this view attached. We are leaning towards a down arrow near the "5th Grade Boys" to open a select list to choose from. Is there another good design up that could be done for iOS and Android?
Answer: The back arrow has a different functionality than showing current page content, I don't think it's the best option. The problem is that within the Divisions section you are changing the title for part of the content of that section when the header should be the section or menu the user is currently in. Below that header, the selected division and the submenu. You only need the division selector.
An option could be a scrollable carousel with all possible divisions to choose from:

Or a simple forward and back buttons beside the current division to move within the division's section:

Update after the comment
If the options to choose from are of a considerable number, a hamburger menu next to the Divisions menu with the largest possible number of options when displaying:
Comment: Nice options, but the first one the event could have 30 divisions and having a user go through all those wouldnt be user friendly. I like the bottom one but again if you have 30, and you want to get to the last one from the first that is 30 clicks.  Just not good user experience options when there are alot of options plus that is a database hit every click so that is not good either.
Comment: Answer updated.-
Comment: Thanks, but I never said I wanted to use the BACK arrown. But a DOWN arrow by the division name to show its clickable.


How does a url gets to know which server it needs to reach?

Question: I was wandering what happens when say we type a url like httt://www.mydomain.com? How does it comes to know where to go to lookout the pages of mydomain.com? How does all this happens?
Answer: http://kb.mediatemple.net/questions/791/DNS+Explained
When a user types in a web address like example.com, or when any software other than a browser attempts to access a domain (such as an email address @example.com), the first step is for the request to go to a DNS server.  DNS servers come essentially preprogrammed so your computer can locate them... the default is set by your Internet Service Provider, though some advanced users prefer to use a different service like opendns.
DNS servers essentially act much like an index of a book.  They return the IP address of the web server hosting the website (or mail, or other service, etc.).  These domain / IP address pairs are configured via the domain's registrar (such as GoDaddy.com), where the website owner can program in the IP address of their web server.
Hope that helps.


Warning: DOMDocument::loadXML(): Empty string supplied as input

Question:
Warning: DOMDocument::loadXML(): Empty string supplied as input in C:\xampp\htdocs\Magento2\vendor\magento\module-config\Model\Config\Structure\Reader.php on line 132
Comment: check your module xml file, you have something missing inside xml file. or you have to forgot close tag
Comment: Check system.log file in log folder.
Comment: I am not finding any issue there! :(
Comment: your issue is related to your xml file mismatch tag or some missing node
Answer: I experienced the same kind of issues. I fixed that issue by remove spacing at start of the xml file.
don't give any space at start of the xml file

<?xml version="1.0"?>
...................
..............

it should be
<?xml version="1.0"?>
...................
..............

if it is not solve your problem, show your module.xml
Comment: It might also be an empty XML file somewhere. I deleted an XML file but the file was put back by some merge but without the contents. Both cases are invalid XML which throws erorrs.
Answer: I found this problem when learning to build modules. Don't pre configuring the files and folder with empty .xml files, be sure to only create an .xml file with correct content and save it. Don't just leave them empty with a view of populating later as magento's error handling will just fall-over.
Answer: There is an empty .xml file in you project and If you don't know where is empty file and you are using linux. Use this command to get list of empty files.
open terminal and type
find  /path/to/dest -type d -empty for dir.
and
find  /path/to/dest -type f -empty for file.
Comment: for files, use f:  find /path/to/dest -type f -empty
Answer: i just encountered this problem and it took me a couple hours for it to finally become enabled. I found that by deleting excess files from the demo file structure example and using the bare minimum for the purposes of getting things going worked for me.
like so:
app/code/Vendor/Test/etc/module.xml

                    Test/composer.json

                    Test/registration.php

While trying to work this out. I tweaked many things. In my last run before it finally worked. I made sure I changed the autoload in the composer to read "PSR-4" to read name\type(a module in this case)and the name.
like so
"Gary\\ModuleTest"

I also got rid of a line space in between
<?php

\Magento\Framework\Component\ComponentRegistrar::register(
    \Magento\Framework\Component\ComponentRegistrar::MODULE,

in my registration.php
like so:
<?php
\Magento\Framework\Component\ComponentRegistrar::register(
    \Magento\Framework\Component\ComponentRegistrar::MODULE,

after that i enabled it and upgraded using php bin/magento setup:upgrade.
Answer: If this issue exists only in Internet Explorer browser, then the possible cause of this issue is due to it's Compatibility View Settings
Turn OFF "Display intranet sites in Compatibility View" under Settings > Compatibility View Settings


Can I use Kingston KVR16LS114 ram on HP Probook 4420s?

Question: Can I use Kingston KVR16LS114 ram on HP Probook 4420s? Hp specifications says the laptop supports DDR3 PC3-10600 SDRAM (1333 MHz). However,crucial suggests DDR3 PC3-12800.  Can anyone help me
Comment: Short answer, yes, HP specs the slowest RAM the machine supports, faster RAM that is otherwise identical works fine, the BIOS will automatically adjust the timings accordingly. On a side note, setup lots of these, don't mix RAM speeds (one PC3-10600 and one PC3-12800 DIMM), the motherboard just doesn't like it even though in theory it should work.
Answer: As acejavelin as stated,
The Manufacturer has specified DDR3 PC3-10600 1333 MHz SODIMM as the recommended memory. DDR3 PC3-12800 1600 MHz SODIMM will also work. Mixing two speeds 1333 MHz and 1600 MHz will automatically run both at 1333 MHz.
So better to go with 1333 MHz, if you're installing along with the existing (1333 MHz)
Kingston KVR16LS114 is for 4 GB DDR3L (1.35v) PC3L-12800 SODIMM - This is the low voltage than the usual DDR3 (1.5v). It is compatible. It will either run at 1.35v or 1.5v depending on the system.
You can refer think link:
http://www.memorystock.com/memory/HewlettPackardCompaqProBook4420s.html


Do objects pushed into an array in javascript deep or shallow copy?

Question: Pretty self evident question...When using .push() on an array in javascript, is the object pushed into the array a pointer (shallow) or the actual object (deep) regardless of type.
Answer: It depends upon what you're pushing.  Objects and arrays are pushed as a pointer to the original object .  Built-in primitive types like numbers or booleans are pushed as a copy.  So, since objects are not copied in any way, there's no deep or shallow copy for them.
Here's a working snippet that shows it:
var array = [];
var x = 4;
let y = {name: "test", type: "data", data: "2-27-2009"};

// primitive value pushes a copy of the value 4
array.push(x);                // push value of 4
x = 5;                        // change x to 5
console.log(array[0]);        // array still contains 4 because it's a copy

// object reference pushes a reference
array.push(y);                // put object y reference into the array
y.name = "foo";               // change y.name property
console.log(array[1].name);   // logs changed value "foo" because it's a reference

// object reference pushes a reference but object can still be referred to even though original variable is no longer within scope
if (true) {
    let z = {name: "test", type: "data", data: "2-28-2019"};
    array.push(z);
}

console.log(array[2].name);   // log shows value "test" since the pointer reference via the array is still within scope

Comment: Nitpicking: every value is pushed *as a value*; in the case of objects those values just happen to be "pointers" to the object.
Answer: jfriend00 is right on the mark here, but one small clarification: That doesn't mean you can't change what your variable is pointing to.  That is, y initially references some variable that you put into the array, but you can then take the variable named y, disconnect it from the object that's in the array now, and connect y (ie, make it reference) something different entirely without changing the object that now is referenced only by the array.
http://jsfiddle.net/rufwork/5cNQr/6/
var array = [];
var x = 4;
var y = {name: "test", type: "data", data: "2-27-2009"};

// 1.) pushes a copy
array.push(x);
x = 5;
document.write(array[0] + "
");    // alerts 4 because it's a copy

// 2.) pushes a reference
array.push(y);
y.name = "foo";

// 3.) Disconnects y and points it at a new object
y = {};
y.name = 'bar';
document.write(array[1].name + ' :: ' + y.name + "
");
// alerts "foo :: bar" because y was a reference, but then
// the reference was moved to a new object while the
// reference in the array stayed the same (referencing the
// original object)

// 4.) Uses y's original reference, stored in the array,
// to access the old object.
array[1].name = 'foobar';
document.write(array[1].name + "
");
// alerts "foobar" because you used the array to point to
// the object that was initially in y.

Comment: Interesting point about using `new` to "disconnect" the object reference.
Comment: Downvote explanation?  Hard to fix the issue if you don't let me know what it was.
Comment: Sorry @Travis -- collateral damage for SO not having another way for me to communicate with the recent anonymous downvoter that came by in the last week or two. I didn't expect it came from you, esp. with your positive comment. Sorry for the unfortunate spam your way, and thanks for staying on top of your question!
Comment: That was actually a misunderstanding on my part. My bad. Your comment showed in my notifications and I thought it was directed at me because I didn't realize that as the OP all comments show as notifications.
Comment: Why ping me? I upvoted this a long time ago and did like your answer. Here is a screen of the vote: http://i.imgur.com/AnDt98c.png
Answer: JavaScript: Create a Deep Copy of an Object in 2023
Do NOT use Object.assign() in JavaScript to copy or clone objects! It creates a shallow copy of your object and will assign deep objects to reference pointers in your copy!
You have two choices.
Use the older, more reliable JSON trick:
const obj1 = JSON.parse(JSON.stringify(YourObject));

Or try the new & improved structuredClone() method. Warning: This only works for users who have updated their evergreen browsers since 2022! No Internet Explorer or Edge Trident browser support!!
const obj2 = structuredClone(YourObject);


Can we exlain Bell's Theorem without dwelving into Quantum Mechanics?

Question: I have recently started learning Quantum Mechanics. We learnt some things on light polarization, so I referred to this site. Luckily I stumbled upon this answer which links to this site which sated my quest for an answer. However, I recalled a video titled "Bell's Theorem: The Quantum Venn Diagram Paradox" by MinutePhysics. Is the classical answer insufficient? Why is it insufficient?
Comment: Bell's theorem is a statement about certain (classical) models, so called "local hidden variable models". There is no reference to quantum mechanics whatsoever.
Comment: by "*explain Bell's theorem*" do you mean "explain the derivation of the result", or "explain the results of a Bell violation"? Because in the first case QM is not involved at all, while in the second case the whole point is that you cannot explain/predict the results within a classical framework. QM correctly predicts physical situations that violate Bell's inequalities, but this does not imply that QM is the only possible theory explaining such violations
Answer: The classical answer is indeed insufficient.  The way to attempt a classical description of a Bell experiment would be to imagine the probabilities for experimental outcomes as being given by a probability distribution over some set of "actual, physical states," called ontic states.  The ontic states are not in general experimentally accessible; you can only measure some of their properties, so they are also called "hidden variables" (some people also use this to mean the probability distribution over them.)  Crucially, the ontic states are seen as existing independent of measurement, and measurement is seen as revealing some of their preexisting properties.  This allows us to preserve our classical intuitions of measurement, i.e., that when we measure some quantity, its value already exists before our measurement.
For example, in the "three-polarizer" experiment you linked to, assuming the light gets through the first filter, you could imagine the possible ontic states to be:
$$\{00\},\{01\},\{1x\},$$
where $\{00\}$ means "will make it through the second and third filters," $\{01\}$ means "will make it through the second filter, but not the third," and $\{1x\}$ means "won't make it through the second filter."  Then we can describe the whole experiment classically by just assigning probability 1/4 to each of the first two ontic states and probability 1/2 to the third.  These probabilities are seen as just encoding our lack of knowledge about the ontic state of each photon, rather than something intrinsic to the photon.
The Bell (EPR) experiment is more complicated, so since there are good resources available to describe it (the wikipedia article on Bell's Theorem is fine), I will not reproduce the details here.  But without going into those, what it basically shows is the one can create an experiment where the (probabilistic) predictions of quantum mechanics cannot be reproduced by any probability distribution over any set of ontic states.  Since such experiments have subsequently been performed, and since they confirm the quantum mechanical predictions, we conclude that quantum mechanics cannot be described classically in this way (by a local hidden-variable theory).


I was wondering what scale the following notes are and how to transpose them on an alto saxophone (B, C#, D#, E, F#, G#, A#, B)

Question: I have been asked to play an audio recording of the scale (B,C#,D#,E,F#,G#,A#,B) but i am not sure which scale this is. It would also be helpful if anyone knew how to transpose these notes on an alto saxophone as well.
Comment: The person who asked you to make the recording is the best one to tell you whether they want the written or concert pitches. How could we know what they are asking for?
Answer: That would be a B major scale, which technically should be G# for Alto Saxophone, but that key is considered only as theoretical (it would have 6 sharps and an F double sharp), so it is normally transposed as Ab.
Answer: This is the major B scale. When you play a C on your instrument you get the tone with a pitch of Eb, i.e. a minor 3rd above C. Thus you have to play the Ab major scale to play B major. (To play a C you must play A - B is a semitone lower than C => Ab)
Answer: The key with 5 sharps in is key B major. I expect that's what the concert pitch is that you've been asked to provide.
Since the alto sax is a transposing instrument, it's no good playing those actual notes, as if you were reading them off a chart. So, what you would do, is play the scale of A♭ major, as if you were reading from a chart, and those key B notes would be sounded. So, write (if you like) A♭, B♭, C, D♭, E♭, F, G, A♭ on a stave, and play them.


Is there a site with all airlines carry-on restrictions?

Question: Every time I look at a which carrier to book for a flight I wish there was a way to go to a single resource (without visiting each carrier's site) to know at a glance which airline gives me the most lenient restrictions, especially when they are at the same price point.  Is there such a resource that is updated frequently as new rules come out?
Comment: The best resource I've ever found for carrier's luggage allowances is in the luggage departments of higher-end department stores. Very handy for when you're considering which bag/suitcase to buy, less so for deciding which plane ticket to buy given the suitcase you already own...
Answer: There are multiple possibilities already existing to have a more or less refined idea of the baggage restrictions. It depends if you want the detailed restrictions on bag sizes or just the cost of a checked bag.
Expedia shows the price of carry-on and checked bags on their flight details, like in the screenshot below.

Seatguru shows, for each airline, the detailed baggage rules, this one is for Air France. You have to pick your airline and then click the Baggage option in the left pane. The page shows rather detailed information. At the bottom of that page, you have a link to the airline's baggage rules page, for even more details (and if the seatguru page is not up-to-date).
EDIT: As @verve commented, do not expect Seatguru to be up-to-date. You should probably better follow the links to the airlines' page.
Finally Skyscanner has a list of links to the airline pages regarding the baggage rules. These are the most accurate, since we do not know how often the two other update their websites.
These are maybe not exactly what you expected and require a few clicks, but it is relatively easy to access, you can bookmark the skyscanner list of links for example. And probably more flight search engines have integrated these, the list is not exhaustive.
Comment: Seatguru hasn't been updated in a long time!  At least the Android app is useless last I checked.


Restore messages from old whatsapp file

Question: i need to restore old messages from a year and a half ago that i have the files of but everytime i load it onto the phone it does not load those messages, can anyone help me? it is also no longer the same phone...
S5 to S6
Comment: Isn't there an online backup of whatsapp files? Like in Google drive? If not, you're in trouble.
Answer: A year and half? I don't think you can do that because WhatsApp changed the encryption system of messages a couple of months ago.
Below is my WhatsApp message backup.
Answer: I don't know how to put it. But I realized something. My friend and I used to exchange phones. At one time after i use his phone and remove his WhatsApp account to  mine, though different numbers, WhatsApp gives me the option to restore backup from drive or SD. When I skip the drive and choose SD, it restores my friend's messages and media to my account and they are visible..
So I think if you have the backup file you can put it in the right WhatsApp directory and get everything going

Restore messages from old whatsapp file


anonymous functions

Question: I have found the support for anonymous functions (lambda expressions) in Yices to be extremely helpful.  I am now trying to use Z3 to implement a tool, but I have not been able to figure out if this feature is supported.  I am invoking the tool using the -smt2 flag.  thanks for your help.
Answer: AFAIK, lambda expressions are neither supported by Z3 (see this answer by Nikolaj Bjorner, one of the main Z3 developers), nor are they part of the SMTLib2 standard. Solvers that support lambda expressions, for example, Yices or veriT, support them as a custom extension to the SMTLib2 standard.
Depending on your needs (which you might want to illustrate by adding an example to your questions) you could try Z3 macros (define-fun), or a front-end like Z3Py that, compared with writing SMTLib code manually, simplifies working with Z3 a lot.

anonymous functions


Why does Vaseegaran use the word "dot" for "agree"?

Question: In the Indian movie 2.0, Vaseegaran uses the word "dot" for agreeing to things. Why does he use the word "dot" for "agree"?
Answer: The word "Dot", apart from being a catch-phrase, is the Chitti (a robot's) way of saying "Period". It roughly translates to him agreeing/affirming to a statement or a work or anything else. You could also think of it as a 'Tech-y way' of saying "Yes", "Sure" or "Ok?"
Comment: Vaseegaran uses dot often in Robot and 2.0 as well. Watch the movie again. It is his catchphrase.
Comment: Oh ! i always thought it was only used by Chitti.. ill rewatch it - thank you for letting me know!


Double Slit Information Destruction

Question: In the double slit experiment, when a detector is added to tell which hole the photon went through the interference pattern disappears.  Would there be an interference pattern if the data was sent to a computer, but never recorded? What if it was recorded but destroyed before anyone looked at it?
Comment: There's no way to convert something into data without measuring it. You'll always destroy the interference pattern.
Comment: Maybe I'm wrong, but I like to think of it as interaction rather than measurement.
So if anything immediately interacts with the particle after it exits one of the slits, there can be determination.
It's not human observation that collapses.
Comment: The central concept here is reversibility/irreversibility. If the detection process is irreversible then it is, well ..., irreversible.
Answer: Yes and no. "Sending the data to a computer, then destroying it" is probably too complex an operation to let the state of a photon produce the same interference pattern again.
Yet, experiments in the spirit of your idea have indeed been performed, by playing around with entangled photons, sending one through the slit and using the other to obtain information about the path taken. They are called quantum eraser experiments: (quoting from the description of such an experiment from Wikipedia)

First, a photon is shot through a specialized nonlinear optical device: a beta barium borate (BBO) crystal. This crystal converts the single photon into two entangled photons of lower frequency, a process known as spontaneous parametric down-conversion (SPDC). These entangled photons follow separate paths. One photon goes directly to a detector, while the second photon passes through the double-slit mask to a second detector. Both detectors are connected to a coincidence circuit, ensuring that only entangled photon pairs are counted. A stepper motor moves the second detector to scan across the target area, producing an intensity map. This configuration yields the familiar interference pattern.
Next, a circular polarizer is placed in front of each slit in the double-slit mask, producing clockwise circular polarization in light passing through one slit, and counter-clockwise circular polarization in the other slit. This polarization is measured at the detector, thus "marking" the photons and destroying the interference pattern.
Finally, a linear polarizer is introduced in the path of the first photon of the entangled pair, giving this photon a diagonal polarization. Entanglement ensures a complementary diagonal polarization in its partner, which passes through the double-slit mask. This alters the effect of the circular polarizers: each will produce a mix of clockwise and counter-clockwise polarized light. Thus the second detector can no longer determine which path was taken, and the interference fringes are restored.

What happens is that though the paths through the slits are in principle distinguishable, no interaction (in particular, no macroscopic interaction that could cause decoherence or whatever you believe happens during a measurement) is actually taking place that would depend on the path the photon takes after the second polarizer is introduced. "Recording data", as you propose, would change that, and so that cannot work.
Comment: @julianfernandez: Well, I'm not 100% certain that some mad scientist may one day come up with something like that since I'm not an expert in quantum information, but in my naive view, to "record data" you'd have to measure the polarization of the photon (or anything else of its properties). That's ordinarily rather impossible without destroying the photon (and thus, entanglement). It could be that "non-destructive weak measurement" of photon polarization I've lately heard of could achieve that, but I'm very reluctant to pronounce on that until I've seen the experiment.
Comment: well, at least you are correct on a standard measurement (recording), I just found that article that put in a complementary answer
Comment: Note, however, that in quantum eraser experiments the interference pattern is never restored in the total pattern of particles on the screen, only in the coincidence count between particles on the screen and entangled twins that went to a particular detector, as I discussed in [this answer](http://physics.stackexchange.com/a/141490/59406). It seems that if the particles going through the slits interact with other particles in a way that would *in principle* allow for a determination of which slit they went through, that's sufficient to destroy interference in the total pattern on the screen.
Comment: So, what you're saying, is that if you introduce a method of measurement, the interference is removed, got that. However, if you introduce a method that disguises the measurement so that it is indistinguishable, the interference comes back. So, Since the measurement was subsequently hidden, its not measurable at the end, and thus the measurement was erased?
Comment: Is it possible to interpret the DS experiment from the perspective of an atomic (indivisible) and coherent (non-contradicting) packet of information each quantum of energy can carry about its latest interaction? Could it be that we found the quantum of information itself in its pure form? Just curious.
Answer: To add a concrete example to ACuriousMind answer's, consider the Schrodinger's cat experiment. An analysis of an actual experiment found that measurement alone (for example by a Geiger counter) is sufficient to collapse a quantum wave function before there is any conscious observation of the measurement. See this paper for more details http://web.archive.org/web/20061130173850/http://www.ensmp.fr/aflb/AFLB-311/aflb311m387.pdf
Answer: Sending data to a computer is not possible without detection, and a detection for sending to some computer is a macroscopic intervention, that introduces decoherence between the two components of the wave-function, that which passed through one hole, and that with passed through the other.
But the issue is simpler. For detecting which hole the photon passed  through, a detector has to be placed quite close to the holes, i.e. where the two branches of the wave-function that which passed through one hole and that which passed through the other, are well-separated. The interference pattern appears there where the branches superpose, and in this region there is no more memory through which hole the photon passed.
In terms of operators, the operator "which hole" does not commute with the operator "minimum or maximum" s.t. s.t. no memory of the "which hole" is retained in the interference pattern.

Double Slit Information Destruction


SKProduct multiple files

Question: The API for SKProduct suggests that it is possible to have more than one downloadable file associated with a single in-app purchase. However in iTunes Connect I do not see any way to achieve this. Is it possible to do this, in particular when hosting with Apple? If so then how?
Answer: Use in-app purchase XCode target to create the package file. Then you can enable Apple hosted content from iTunes Connect
Comment: As far as I can tell, this still only allows one download per IAP.

SKProduct multiple files


How do we fetch data through REST service which hosted in azure from SharePoint site which in office 365?

Question: How do we fetch data through REST service which is hosted in window azure, from SharePoint site which in office 365? Can we need to create app for SharePoint which contain restAPI endpoint or any better solution than this?
Answer: You need to allow CORS to be able to do this. The problem is that javascript doesn't allow cross domain calls, and the Azure service can't have the same domain name as your Office 365 (At least I'm pretty sure of this).
By enabling CORS support in your Azure REST API, you can circumvent this. Do be warned however, that CORS must be supported by the browser too. I know there's some different behaviour between IE and other browsers in this regard.
Creating a SharePoint app actually also creates a new (sub)domain, so it won't work.
https://azure.microsoft.com/en-us/documentation/articles/app-service-api-cors-consume-javascript/
Comment: Actually, creating an app would work, could use [Web Proxy](https://msdn.microsoft.com/en-us/library/office/fp179895.aspx).
Comment: Hi Christoffel, here, RESTAPI which hosted on azure using httpwebrequest(c#) to get data from SharePoint online. In this case also will CORS work? Thanks in Advance..
Comment: Thanks eirikb, @user21853 C# will always work, CORS is not necessairy.


How should I stop condensation on my roof that's leaking into my home?

Question: Condensation in my attic causes frost which melts on warm days and leaks through my ceilings. I plan to add more insulation this spring. I have installed a bathroom ceiling fan to help with moisture. My research tells me that other factors are #1 I have a dirt crawl space #2 propane heat #3 we have replaced doors, windows, siding etc. making it harder for the house to breath. Should I consider an exhaust fan for the attic? What other options do I have?
Answer: The two main reasons I know of for condensation in an attic are a lack of air circulation from soffit to ridge vent and air leakage from the house typically due to an improperly vented exhaust fan or insufficient vapor barrier between the insulation and top of the ceiling.
I'd focus on the first cause by making sure your soffits are vented and there's a clear path from the soffit up to the ridge vent. Too often dirt and debris block the vents and homeowners force insulation all the way to the roof blocking the air flow. After that is checked, follow the ducts from any bathroom exhaust fans to make sure they vent outside the home. In a best case, they go out the side of the house, well away from the soffit vents, or at least out the roof. But at a minimum they should go out near the soffit (where much of it will get sucked back into the attic) and not left venting into the attic directly. Lastly, check under the insulation to be sure there's either the paper facing of the insulation or a plastic vapor barrier between the insulation and the ceiling below.


Remove public from URL Laravel 5.3

Question: I'm using Laravel 5.3 is there a easy way to remove public from URL? is it necessary to add a htacces. when I change the htacces it is getting a n error like below,
Answer: copy both htaccess and index.php file from public folder to root directory and then change root index.php code as below
require __DIR__.'/bootstrap/autoload.php';
$app = require_once __DIR__.'/bootstrap/app.php';

Comment: It's too risky. It makes your composer.json, .env and others sensitive information accessible via browser. Best practice is to set vhost to /public.
Comment: @MahfuzulAlam.Thanks for notifying in comment
Comment: I'm sorry, but I have to say this. It's a really bad advice since if you do that, you'll catch a lot of errors during development and whole you app code will be open to the web.
Comment: @AlexeyMezenin. i hope he is using localhost otherwise he would have pointed domain to public folder itslef
Answer:
After installing Laravel, you should configure your web server's document / web root to be the public directory. The index.php in this directory serves as the front controller for all HTTP requests entering your application.

https://laravel.com/docs/5.3/installation#configuration
Do not edit .htaccess or Laravel related files, just point web server to a public directory instead of Laravel project directory:
DocumentRoot "/path_to_laravel_project/public"
<Directory "/path_to_laravel_project/public">

Then restart Apache.
Comment: This is the correct approach but Latest XAMPP (32-bit) on Windows 7 is not playing nicely. So, my team is implementing the Accepted answer given above.
Answer: Add a .htaccess file in root which contains -
RewriteEngine On
    RewriteRule ^(.*)$ public/$1 [L]

Answer: Yes it is very simple no need to add extra htaccess,

Create a new folder in your laravel project folder.
Name it whatever you like. Example :- source

Move all the files from root  into 'source' folder except 'public' folder.

4 . Move all the files from public folder to root.

5 . Change the autoload.php path
6 . Thats all.  remove public folder if necessary.
Answer:
In the root directory create a .htaccess file and put the following in
  it

<IfModule mod_rewrite.c>
   RewriteEngine On
   RewriteRule ^(.*)$ public/$1 [L]
</IfModule>

Answer: Even above solution(s) work(s) for you,but I would recommend not to do this.
Here is the reason why.
-You should be pointing your Apache host root to the $LARAVEL_PATH/public directory instead of $LARAVEL_PATH.
-you have to configure apache for user not access .env, git files , config folder's file
public directory is there for reason to make project a bit more secure. Solve the actual problem and don't try to break this simple but nice security addition.
Answer: Copy all files and folder from public folder to root folder and edit your .htaccess file as
 <IfModule mod_rewrite.c>
    RewriteEngine on
    RewriteCond %{REQUEST_FILENAME} !-f
    RewriteCond %{REQUEST_FILENAME} !-d
    RewriteRule ^(.*)$ index.php/$1 [L]
</IfModule>

And dont forget to change the paths in index.php file.
For details refere following links
Installing Laravel in a subfolder
https://ellislab.com/forums/archive/viewthread/151342/#734511

Remove public from URL Laravel 5.3


Tool to find unused javascript functions

Question: is there a tool that I can run to find any javascript functions which aren't called from anywhere in my library?  (Looking to cut any functions that are no longer being used but weren't cleaned up in the past)
Answer: There are a number of libraries ( 'linters' ) that will help you not only find unused functions, but also will point out common potential issues in your code.  The most common ones are jslint and eslint. Either of those will go a long way to help avoid common mistakes. Many of them can easily integrated into development environments in atom or vscode.
Comment: I would definitely go with a Linter (read about [static code analysis](https://en.wikipedia.org/wiki/Static_program_analysis)). One gotcha to look out for, is that, in JS specially, some functions will appear not to be called if they are callbacks.


Logged out right after login after docker install

Question: My computer was fine a working properly until I tried to install Docker. Everything looked like it went well. It was successfully installed and running the hello world worked. I then went on to the extra configuration steps to Manage Docker as a non-root user (https://docs.docker.com/engine/installation/linux/ubuntulinux/#/manage-docker-as-a-non-root-user)
I ran
<code>sudo groupadd docker
sudo usermod -aG docker $USER
</code>
Then moved on to step 4. It said log out and back in, but I installed a bounch of things and I like to restart my computer to reset any caches and to have everything running smoothly (I don't think restarted instead of just logging out was the issue).
When the computer came back on, and I already noticed something different. Usually when I boot into the computer, once I get to the log in screen my second moniter usually turns on and it wasn't turning on at all. I thought that maybe it would just turn on once I logged in (as one of the monitors was on). Once I log in a black screen pops really quickly with 1 line on the top of text but it too quick to read(looks like it was loading user settings or something) then pops back to the log in screen, and when It pops my back to log in screen it mutes the sound (as I see the mute sound image).
Things I have tried (from I am logged out immediately after logging in and other sources):

Verified that it was still checking user credentials by typing in the wrong password.
logged in with (ctlr+alt+f1) and removed .Xauthority
logged in with (ctlr+alt+f1) and restarted lightdm
Both 2 and 3 together
I reinstalled ubuntu-desktop and unity and restarted and tried again.
logged in with (ctlr+alt+f1) then I looked to see who owned the home directory of my user (as someone suggested) and is owned by the user I am trying to log in as.
As login as guest is enabled, I tried to log in as the guest instead and had the same issue.

I am not really sure how to solve this so any help would be appreciated. Few extra notes: I am using Ubuntu 16.04 and I followed the instructions exactly on the page I linked above for my version for installing docker. Before I installed anything I just powered my computer on and with no issue so it couldn't have been something that wasn't while I was installing docker.
Answer: So it turns out that when I installed the packages with docker it messed up something with my graphics driver (not sure how). After re-installing my graphics drivers everything seemed to work fine.
here is where I found a solution that actually worked: login loop after upgrade to 16.04


Is there a way to escape keyboard focus from adobe flash?

Question: I've been trying to use the mouse less when web browsing. However, if a flash program gets the focus, it will capture the all the keyboard strokes, making it impossible to do anything without moving the mouse first. Is there any way around this?
Comment: I'll admit this is one of the most annoying features of most flash pages, when my default Firefox shortcuts no longer work due to some flash app.
Comment: Using Vimperator on Linux, I've also had this issue, and it's really annoying.
Comment: While I can understand the need for it for *certain* Flash applets, this has been annoying me with Chrome (and pretty much all browser for that matter) for years. I have to click the mouse somewhere in the page (outside of the Flash applet) to be able to do so much as changing tabs. `:-|`
Comment: Which browser do you use?
Comment: Firefox, on XP and Ubuntu, but mainly XP.
Answer: It seems this is a bug in Firefox that is over 8 years old without an easy fix, judging by the comments. There is an experimental add-on you may want to try called Restore Window Focus After Flash, but that is just one user's perspective on which hotkeys should work within flash, and how it should operate - it may work out well for you though.There are many possibilities on how to handle the situation, which are outlined in the bug report comments, although it seems Mozilla hasn't accepted any of them yet or taken action of their own.
Comment: There is even a bounty on the fix - http://www.fossfactory.org/project/p81
Comment: Just to note, the extension is no longer available.
Comment: That's interesting, $107.06 has been put towards it too!
Answer: Seeing your question, I decided to do some tests to try to find a way to move focus from a Flash object, back to the page using just the keyboard. I tried it on Windows in Firefox, Chrome, Opera, and IE. Here's the results with the simplest steps to accomplish the goal:

Firefox retains focus on the Flash object no matter what (practical/reasonable/feasible steps) I tried, so you may want to use the Firefox add-on that John mentioned
Chrome releases focus from the Flash object if you tap either the Windows or Alt keys twice in a row
Opera releases the focus by pressing Windows, then Alt-Tabing back to Opera
IE seems to put the Flash object in the normal tab-order of the page, so tabbing will move from elements in the page to the controls in the Flash object, then out to subsequent elements on the page, so tabbing enough times will bring the focus back to the page
Answer: On Windows, try the following:

press Ctrl+Shift+Esc to open Task Manager
press Ctrl+Tab or Ctrl+Shift+Tab until you get to the Processes tab
find plugin-container.exe in the list and press the Menu key or Shift+F10 to open the context menu
press T and Enter to kill the process tree
press Alt+Tab or Alt+Shift+Tab to switch back to Firefox and enjoy your Alt key again

This kills Flash support for the process, but since windows are processes in default config, you can press Ctrl+N it back.


How to prove that $n!>2^n$ holds for all $n>3$?

Question: I suspect something with sets since one with cardinality $n$ has $n!$ permutations and its powerset contains $2^n$ elements. It could also involve binomial coefficients because of$$\begin{pmatrix}n\\0\end{pmatrix}+\begin{pmatrix}n\\1\end{pmatrix}+\begin{pmatrix}n\\2\end{pmatrix}+\cdot\cdot\cdot+\begin{pmatrix}n\\n\end{pmatrix}=2^n$$
Comment: It's an easy induction on $n$.
Comment: Do you want a combinatorial interpretation? Base on your question you should tag it in combinatorics or combinatorial proofs.
Answer: The number $n!$ is the product of the $n-1$ numbers $2,3,\ldots,n$, each of which is greater than or equal to $2$ (and all of them but $2$ is actually greater than $2$) and, since $n>3$, at least one of them is greater than or equal to $4$. So, $n!>2^{n-2}\times4=2^n$
Answer: If $n!>2^n$ multiply both sides by $(n+1)$ to get
$$
(n+1)!>(n+1)2^n> 2 \times 2^n > 2^{n+1}
$$
with minor details to be filled.
Answer: I think it's simpler than you're suggesting. Are you familiar with proof by induction? Here's a hint: once you know that $4! > 2^4$, look at how you get from $4!$ to $5!$ and from $2^4$ to $2^5$. If you can prove it for $n = 5$ given that it's true for $n = 4$, can you continue that process?
Answer: multiply both sides by n+1
Then prove that $(n+1)!2^n$ is greater than $2^{n+1}$
Answer: The OP was not very clear if them were looking for a combinatorial interpretation, in such case:
Consider the following function $Fix : S_n\longrightarrow P([n]),$
called the set of fixed points of a permutation, where $S_n$ is the set of permutations on $[n]$ and $P([n])$ is the powerset of $[n],$ defined as
$$Fix(\pi)=\{i: \pi(i)= i \},$$ for some permutation $\pi ,$ meaning we are recording the fixed points of the permutation.
Notice that if we fix $n-1$ points in the permutation, we are fixing $n$ because there is no space to make the$ n-$th element not fixed. So any set $A\subseteq [n]$ such that $|A|=n-1$ is not the set of fixed points of any permutation. So, apriori, $$n!=|S_n|\geq 2^n-n+1.$$
We actually can say more, using the Derangements(permutations without fixed points, denoted by $D_m$) we can decompose $S_n$ in the statistic of how many fixed points the permutation has i.e.,
$$n!=\sum _{k=0}^n\binom{n}{k}D_{n-k}=\sum _{k=0}^{n-2}\binom{n}{k}D_{n-k} +1,$$
where the last equality is by the argument above on how there are no permutations that fix $n-1$ points exactly. Now, notice that $D_{n-1}>2$ iff $n>3,$ because $D_k>D_{k-1}$ for $k>1$ (why? ). So we can split this as $\binom{n}{1}D_{n-1}=\binom{n}{1}+\binom{n}{1}(D_{n-1}-1)=\binom{n}{n-1}+\binom{n}{1}(D_{n-1}-1).$ So we have that
$$n!=\sum _{k=0}^n\binom{n}{k}D_{n-k}=\sum _{k=0}^{n-2}\binom{n}{k}D_{n-k} +1=D_n+\binom{n}{1}(D_{n-1}-1)+\sum _{k=2}^{n-2}\binom{n}{k}D_{n-k}+\binom{n}{n-1} +1>\sum _{k=0}^n\binom{n}{k}=2^n.$$
Answer: Since $n\ge 4$ we have $n! = 1\cdot 2\cdot 3\cdot 4 \cdot 5\cdots n = 24 \cdot 5 \cdots n > 16 \cdot 5 \cdots n\ge  2^4\cdot 2 \cdots 2 = 2^42^{n-4}=2^n$


Which is the mission 'Out of bullets'?

Question: I would like to get the achievement Out of Bullets but I don't have the English version of the game. Can you please tell which is the number of mission called 'Out of Bullets'? Or post me a screenshot of that scenario?
Comment: Here's a hint for playing the actual levels: love the meteor tower. They're your best bet to punch through the shielded aliens / bulwarks
Answer: Okay, so this achievement is a little missleading. It's not a mission or campaign pack that's called "Out of Bullets"; instead, it refers to a specific challenge mode available to some story missions (5 in total)
Comment: @Juan - use them when you play sniper, so you can wear shades with your shades, and look cool when you look cool.
Comment: I used this ticket to get me some cool shades for tf2
Answer: It's not the name of an actual mission. It's a mode for the normal original levels.
See:

Edit: I took screenshots of the first mission that you can play in 'Out of Bullets' mode (which was added in a recent update).
Comment: Hello jaml, and welcome to gaming.stackexchange! It may interest you to know that stackexchange lets you embed images in your posts (via imgur, no less). There's no need to upload them on a separate site, the stackexchange engine will take care of all of that for you.
Answer: Search for the Out Of Bullets game mode on five of the original levels. Select campaign "The Awakening" and mission "Ancient Research".

Which is the mission 'Out of bullets'?


How to select a sprite with the mouse in c# XNA?

Question: I'm attempting to create a chess game, for the movement I need to be able to click on a piece with the mouse, and then the square I'd like to move it to. Each piece on the board is a sprite, and I'm struggling to find a way to select a sprite in order to then move it, what would be the best way to do this? I'm programming in c# with XNA framework btw. Thanks in advance :)
Comment: This problem is called "picking" - [searching "XNA picking" turns up some promising looking tutorials and past Q&A that might help you](https://duckduckgo.com/?q=xna+picking&ia=web).
Answer: I think the best way would be to make a rectangle for the position and hitbox of each of your chess pieces.
After that make a rectangle for the mouse pointer, and use the Rectangle.Intersects method to check if your mouse hitbox intersects with one of the pieces hitboxes, and of course do your logic there.


C* tensor product admitting a faithful separable representation

Question: Let $A$ and $B$ be $C^* $ algebras which admit faithful representations on separable Hilbert spaces.
Is this property passed on to $C^*$ tensor products $A \otimes_\beta B$?
Comment: Well the answer is obviously yes for the minimal tensor product, thus obviously yes if $A$ or $B$ is nuclear and it is also obviously yes if $A$ and $B$ are both separable, but I'm not sure about the general case
Comment: @JustDroppendIn Thanks for the answer! Could you explain why it's 'yes' for the minimal one?
Answer: This is not a complete answer.
For the minimal tensor product this is direct: If $\pi:A\to B(H)$ and $\rho:B\to B(K)$ are representations of $A,B$, then one gets a $*$-homomorphism $\pi\odot\rho:A\odot B\to B(H\otimes K)$ that satisfies on elementary tensors $\pi\odot\rho(a\otimes b)=\pi(a)\otimes\rho(b)$. If $\pi,\rho$ are faithful, then $\pi\odot\rho$ is injective. So, in general one defines a seminorm on $A\odot B$ by setting $\|x\|:=\|\pi\odot\rho(x)\|_{B(H\otimes K)}$ for all $x\in A\odot B$. When $\pi,\rho$ are faithful, this is actually a norm. It can be proved (see e.g. Brown-Ozawa) that this norm is independent of the choice of $\pi,\rho$, i.e., if $\pi':A\to B(H')$ and $\rho':B\to B(K')$ are other faithful representations of $A,B$, then $\|\pi\odot\rho(x)\|_{B(H\otimes K)}=\|\pi'\odot\rho'(x)\|_{B(H'\otimes K')}$ for all $x\in A\odot B$.
Now $A\otimes_{\min}B$ is defined as the completion of $A\odot B$ with respect to this norm that is obtained by any choice of faithful representations. In particular, if $A,B$ admit faithful representations on separable Hilbert spaces $H$ and $K$ respectively, then $A\otimes B$ is faithfully represented on the Hilbert space $H\otimes K$, which is separable.
As a corollary, if $A$ or $B$ are nuclear, the answer to your question is "yes".
Also (exercise) it is evident that any separable $C^*$-algebra admits a faithful representation on a separable Hilbert space, the reason being that every separable $C^*$-algebra has a faithful state; the GNS Hilbert space of a state of a separable $C^*$-algebra is separable. As a corollary, if $A,B$ are separable, then so is $A\otimes_\beta B$ for any $C^*$-tensor product, so again in this case the answer to your question is "yes".
For the general question, I don't know, I don't see an obvious reason for this to be true. I don't even see a reason for the property to pass to the maximal tensor product.


Calculation of pH in Molecular Dynamics simulation?

Question: I have a system that has 5M aluminum hydroxide (10 molecules) ion [Al(OH)4]- and 5M NaOH (10 molecules) in a box of side length 15 angstroms each. I have 113 water molecules in the system, so that the density of water is consistent with 1g/cc. I need a way to find the pH of the simulation. I tried calculating it by counting the H+ ions, but that gave me a value of ~1.2, which did not really make sense.
Comment: +1 but have you tried using "activity" instead of "concentration"?
Comment: I am trying to match the simulations with experiments. So I need to know the pH, because the experiment was conducted at a certain pH.
Comment: How would you count H+ ions if there isn't any? pH can be inferred from how many hydroxide ions are there.
Comment: What kind of force field are you using? Or is this ab initio? Typical molecular dynamics simulations have fixed protonation states that you set initially. Another option is constant-pH MD, where you set the pH and the protonation states fluctuate. If you are using a reactive force field (ReaxFF?), it might be possible to observe spontaneous deprotonation/protonation, but the number of hydronium ions may be too small to observe.
Comment: I'm using a modified implementation of ReaxFF.
Answer: What matters is the number of "free" H+ ions. A quick estimation using the autoionization constant of water shows that the H+ concentration is on the order of $10^{-15}$ mol/L. Obviously, it is essentially impossible to see even one H+ ion in a simulation of merely 100 water molecules. If you do see at least one H+, please check if you have used a wrong criterion for determining whether a hydrogen atom is H+, or if your MD simulation setup has a severe problem (for example you have added the wrong number of Na+ ions).
In any case, if you do not need very high accuracy, say if your result only needs to be accurate to about $\pm$1, then this is an elementary analytical chemistry exercise. You can simply look up the experimental pKb of [Al(OH)4]- and solve for the equilibrium concentration of OH-; then, using the autoionization constant of water, you can easily find the concentration of H+ and therefore the pH. For higher accuracy, you may need to consider the activity coefficients (https://en.wikipedia.org/wiki/Activity_coefficient), which can be rather accurately calculated by the ionic strength, the latter of which can be calculated easily from the components of the solution. Still, this is something you can calculate by hand within one hour. By contrast, MD simulations probably have larger error bars than what can be obtained by the above procedure (due to method and statistical errors), and is much more involved, so I don't recommend using MD to solve this problem.
Comment: As a quick estimate -- 1L = 1e24 nm^3, so 1M is about 0.6 particles (or ions or molecules) per cubic nanometer.
Comment: @Argyll the "hydronium ion" is useful for chemical reasoning (HCl doesn't spontaneously ionise -- it transfers a proton to water). But at molecular level H+ is solvated by anywhere from 2 to 20 water molecules at once -- so "H3O+" isn't fully accurate either, even though it's a good model for chem ed. See J. Chem. Educ. 2011, 88, 7, 875 and related papers for more info.
Comment: I know the OP started the phrasing of "free H+ ions". But typically we are taught that free hydrogen ions dont exist in water -- cuz if it did, it'd bind to a water molecule to form hydronium. So it's all hydronium ions. Is hydronium ion what you mean when you wrote free hydrogen ions?
Comment: I do not have free H+ ions in the box. What I have are 10 OH- ions from NaOH and 10 [Al(OH)4]- ions in the box.
Comment: @ShernRenTee: I see. Thank you for the reference.
Comment: @Argyll Exactly, and my argument extend to the case where the OP is counting H3O+ instead of H+, or even (H2O)nH+ where n is an arbitrary positive integer. That's why I'm surprised that the OP could find at least one H+ in the system, regardless of how the OP defined what a H+ is.
Answer: Here's some useful intuition for solution molecular dynamics:
One litre contains $10^{24}$ cubic nanometers. One mole contains $6 \times 10^{23}$ particles. So 1M of volumetric density corresponds to a number density of 0.6 per cubic nanometers.
The self-dissociation constant of water is $K_w = 10^{-14} [\mathrm{M}^2]$. So at equilibrium and pH 7, both $\mathrm{H}^+$ and $\mathrm{OH}^-$ will have a concentration of ${10^{-7}}$ M.
By the above calculation, this is 60 ions of each type per cubic micron.
As such, it is not feasible to directly simulate water dissociation to probe pH. Rather, the process is modelled using grand-canonical Monte Carlo exchange with a reservoir (essentially "chemostatting", in analogy to barostatting and thermostatting). For example this recent paper chemostats on the combination of acid/base dissociation and electrolyte ion insertion/removal to reach feasible reaction probabilities.
ReaxFF results would certainly not be trustworthy until proven otherwise, since how could they possibly calibrate parameters to exactly achieve sub-micromolar concentrations of hydronium and hydroxide in pure water?


Do GitHub's statistics of visitors and cloners include owners?

Question: GitHub's UI offers a graph of (unique) visitors and cloners. Question is, does that include visits and clones by yourself, as an owner of a project? If not - what about visits and clones by recognized contributors?
Answer: It definitely seems to include owner visits in the graph. I have a GitHub repo that I just started last week and is very small, with almost non-existent web traffic. I visited it today, and the graph went from 0 unique visitors to 1.  Similarly, on a day last week when I worked on the project, the graph shows 1 unique visitor (as compared to 0 for most of the rest of the week).


How to design GUI for my embedded design

Question: I have designed my embedded software and it is working fine. I was thinking about making good GUI so that it is easy for others to interface with my software.
Comment: What is your development platform, Windows or Linux? I have used embedded QT. [Accelerometer Application on Embedded Linux](https://www.youtube.com/watch?v=bd7ULY1frA4)
Comment: which programming language you have used in embedded qt. I am interested in QT but dont know how to set it up for my project. I am comfortable in both windows and linux but if you can tell me how to setup embedded qt for windows then it will be great.
Comment: I have only setup embedded QT for linux. I used 'C'. QT is an IDE
Answer: This depend on which operating system you are using.
If you are on linux, i would recommend you using gtk/glade.

Install GCC and other basic requirement,then install GTK library
Install Glade in your system which is used to make UI interface
Choose you IDE, like eclipse is best in this case. Add path to your gtk libraries in eclipse
Make UI in glade and then program it using gtk libraries in eclipse.

This is all you require to build a professional level GUI in linux for your embedded design.
If you are in windows , I would say go for visual studio . It is best and provides many functionality.
Comment: Great can you give a link to any tutorial for gtk/glade


Using Greenie grounding connectors

Question: I'm trying to figure out exactly how to use Greenie grounding connectors. In a 2 or 3 gang metal box, can I join each receptacle's ground wire and then fasten the single wire coming out the tip of the Greenie to the metal box with a grounding screw. Is this an acceptable way to ground multiple receptacles using a Greenie?
Comment: This image of a Greenie (https://i.stack.imgur.com/S14gV.jpg) is showing the opposite of what I'm suggesting.
Answer: Green wirenuts with a hole in the tip are stupid.
You're not supposed to stick one of the wires in the top. You're supposed to stick all the wires in the bottom, and one of the wires is 9" longer than the others and is supposed to stick through to let you ground one more thing.
What does this mean? You're supposed to strip about 18" of Romex sheath off, and then cut 9" off all wires but the ground wire.  So you are wasting nearly a foot of Romex.  The logic is you are supposed to use the cutoff wires as pigtails later.  Meh.
What is pictured is a perfect use case for it, though, as it already has 6 ground wires incoming and 3 switches to also deliver grounds to.  Without tricks, you'd need to put 9 grounds under a wirenut, (plus one for the box). They don't make 10-wire nuts, so you'd need to be split into 2-3 wirenuts with a pigtail between them.  This latter approach is exactly what I would do.
Answer: The green wire nuts made for grounding are not a NEC requirement, and they're really not that special.  The hole in the end is the key feature.  There's a number of ways you can use them, and it's really just a matter of what you feel makes life easy and makes a solid install.
If you leave one of the ground wires long, you can splice all the ground wires coming into the box, run the long one through the hole, and hit all the devices with that one.
What if you didn't leave one long?  You could make a big long bare wire pigtail, terminate one end on the ground screw, then run it through the hole in the greenie.  Then twist and splice all the ground wires coming into the box with the greenie, then use the other end of the pigtail to hit every device.  If you have a massive box with a zillion ground wires you could make an even longer bare pigtail, and thread multiple greenies on it.
Most of what you can do with greenies, you can do with crimp rings.  Crimp rings are cheaper and take up less space, but greenies are much easier to undo and redo.

Using Greenie grounding connectors


Can you use both 3.3v and 5v

Question: Can you use an Arduino EtherMega's 3.3v and 5v pins with two sensors, one requiring 3.3v and the other 5v and a sketch that combines both?
Answer: Yes. As long as you take into account that the outputs of the Arduino will be 5V so you may need to reduce that to 3.3V for the 3.3V sensor (if it has any connection to an output).

Can you use both 3.3v and 5v


Hiding email address in Windows 8

Question: When you've got Windows 8 'metro' interface open it's got your MS Account right at the top for the world to see.  I often use my laptop in public places and I'm not keen on having my primary email address visible to anyone sat next to me.  Is there a way to hide (or at least rename it?)
Comment: If you put in your first and last name to your account on your Microsoft profile page, then your name will show in place of your email address. I had the same issue.
Comment: I have both my full name AND email showing...
Answer: You need to log on your microsoft account and fill out your first and last name, then log off and back in.
After that, your name will appear instead of your email.
Alternatively you could convert your live account to a local account, but that would obviously stop the syncing with Microsoft services.
Comment: If this still throws up paranoia alarms, Use an alias when you fill in your name.
Answer: I guess Liath is talking about the email address displayed under the full name on lock screen. Don't think currently it is possible to hide that. That's really annoying!
Comment: And also when you entering the password after 'choose user' screen. Annoying truly.

Hiding email address in Windows 8


More groups in common than total groups?

Question: I got a friend request on Steam so I checked out the user's profile to see the groups and friends we have in common only to find out that he has 3 groups and we have 4 groups in common (sorry about the Finnish screenshot):

How is it possible that we have more groups in common than he has in total?
Answer: It turns out the total groups list does not include official game groups, but the groups in common does. The difference in this case was the official Payday 2 group, which was excluded from the total groups count.


Proof by induction:$|\sin(x)| ≤|x|$, for any $x \in \mathbb N$

Question: Firstly We verify for $1$ and holds, Secondly we know for $n$ and we prove it for $n+1.$ if I write $n+1$,  $|\sin(x+1)| ≤|x+1|$
$|\sin x\cos1+\cos x\sin1| \le|x+1|$ we this  $|\sin(x)| ≤|x|$ and how can I use this formula. Furthermore How we find this formula without induction.
Comment: $x$ is supposed to be a real number so induction is not applicable for the proof, unless you are restricting $x$ to say natural numbers.
Comment: You can try prove it showing for $n\in \mathbb{N}$. After that, conclude for $r\in \mathbb{Z}$. Then, show that is true for $q\in \mathbb{Q}$. Use the fact that $\mathbb{Q}$ is dense in $\mathbb{R}$ and generalize to $\mathbb{R}$.
Comment: @AnuragA You can prove it by continuous induction, though.
Answer: If $n\in \mathbb{N}$ then by the triangle inequality and by the inductive hypothesis
$$\begin{align}|\sin(n+1)|&=|\sin(n)\cos(1)+\cos(n)\sin(1)|\\
&\leq |\sin(n)|\underbrace{|\cos (1)|}_{\leq 1}+\underbrace{|\cos (n)|}_{\leq 1}|\sin (1)|\\
&\leq |\sin(n)|+|\sin (1)|\leq n+1.\end{align}$$
P.S. As pointed out by Peter Foreman, the inequality is trivial because for any real $x$ such that $|x|\geq 1$,
$$|\sin(x)|\leq 1\leq |x|.$$
However, by using the same approach we can prove this more general inequality (for $x=1$ we recover the previous one): for any $x\in\mathbb{R}$ and  any $n\in \mathbb{N}$,
$$|\sin(nx)|\leq n|\sin(x)|.$$
For the inductive step:
$$\begin{align}|\sin((n+1)x)|&=|\sin(nx)\cos(x)+\cos(nx)\sin(x)|\\
&\leq |\sin(nx)|\underbrace{|\cos (x)|}_{\leq 1}+\underbrace{|\cos (nx)|}_{\leq 1}|\sin (x)|\\
&\leq |\sin(nx)|+|\sin (x)|\\
&\leq n|\sin(x)|+|\sin (x)|=(n+1)|\sin(x)|.\end{align}$$
Comment: @PeterForeman Thanks for your comment. Please see my P.S.
Answer:
If the central angle is $x$ within a unit circle then the red segment is shorter than the arc which bounds it. That will give the desired inequality.


Starting issue on a Fiat Uno Fire 1100

Question: My car starts normaly 90% of the time. Sometimes when you turn the ignition it just clicks. If I switch it off and turn it again it starts. Sometimes it happens two of three times but then is starts normal. I've even tried ten times and every time it starts normal. Could it be the soleniod or what? Please help
Comment: What year is your car?
Answer: Based on the symptoms described, there seems to be trouble with sending current to the starter motor. Here are the top suspects:

Malfunctioning starter relay switch.
It could well be that the solenoid inside relay is sticking, preventing the switch on the starter side from closing and turning the engine over. This would explain why sometimes you do not hear the starter relay click (complete silence).

Bad ignition switch.
If the ignition switch isn't completing the circuit to the starter relay, the car won't start. I'm a little skeptical that this is an issue given that the dashboard lights come on when the key is in the 'On' position but it is a distinct possibility.

Failing starter motor.

Starting issue on a Fiat Uno Fire 1100


Marketing Cloud - Decrypt File - "Secret key not found in key data"

Question: We have an integration that is sending a .pgp encrypted file to our Marketing Cloud FTP. Once the file is dropped into our /import folder, we are attempting to import and decrypt, it into Marketing Cloud via Automation, however we are running into an error that support has shared with us of "Secret key not found in key data".

We've generated a new PGP 4096-bit key pair using .ASC file format, and uploaded the Private Key into Key Management as the key type of Asymmetric.
In our Automation, during our File Transfer step to import from the FTP, we are running into an ambiguous error of "Secret key not found in key data"
When testing the decryption external to MC using the same private key, it decrypts the file successfully.

Edit: A new error was found by support:
Org.BouncyCastle.Bcpg.OpenPgp.PgpException: Checksum mismatch at 0 of 20 - from BouncyCastle.Crypto
Answer: This was a passphrase issue. We had to remove some of the special characters we included in the passphrase and the decryption worked in the File Transfer step.


The difference between the equation of Permittivity and Permeability in a medium

Question: I notice that the equations of Permittivity and Permeability in a linear medium are exactly opposite of each other. One is $$\mathbf{D} \equiv \varepsilon \mathbf{E}$$ while the other one is $$\mathbf{B} \equiv \mu \mathbf{H}$$ For the electrostatic, the $$\varepsilon$$ multiples directly to the electric field in free space, but the $$ \mu$$ multiples directly to the magnetic field in a medium. Why is it the case? My current guess is that it is because the electric field is weaker in the present of a medium(because the induced charge partly cancelled out the external electric field), but the magnetic field, depending on the medium, may become stronger than the external magnetic field
Comment: H is not the magnetic field in a medium. It is just the magnetic field.  In vacuum too.
Comment: But like D, H is something that we cannot measure directly as field and stay the same even if I change the medium. Am I right?
Answer: This is really a matter of convention. We could have defined $\mu' = 1/\mu$ and defined $\mathbf{H} = \mu' \mathbf{B}$. It turns out that although $\mathbf{E}$ and $\mathbf{B}$ are the "fundamental" electromagnetic quantities, $\mathbf{H}$ is really more like the magnetic counterpart to $\mathbf{E}$, and $\mathbf{B}$ is more like the magnetic counterpart to $\mathbf{D}$. Consequently, it makes sense to keep the definitions in parallel with the $\mathbf{E}$ field.
One way to see this parallel is to notice the symmetry between $\mathbf{D}$ and $\mathbf{B}$ and between $\mathbf{E}$ and $\mathbf{H}$ in the macroscopic Maxwell's equations with magnetic charges and currents:
$\nabla \cdot \mathbf{D} = \rho_{e}$
$\nabla \cdot \mathbf{B} = \rho_{m}$
$\nabla \times \mathbf{E} = -\frac{\partial \mathbf{B}}{\partial t} - \mathbf{J}_m$
$\nabla \times \mathbf{H} = \frac{\partial \mathbf{D}}{\partial t} + \mathbf{J}_e$
In an experiment, you also tend control to control $\mathbf{E}$ and $\mathbf{H}$ and not $\mathbf{D}$ and $\mathbf{B}$. e.g. if you use voltages and currents to generate electric and magnetic fields. Voltage directly determines $\mathbf{E}$ and the free current that you supply determines $\mathbf{H}$, not $\mathbf{B}$.


What level should I be by the time I face the Warden in Borderlands 2?

Question: So I epically failed the first time and it looks like I ended up going the friendship gulag route. The problem is I still cant' beat the warden. I was at level 12 and I was getting absolutely no where, so I left the mission and went and did a few side missions. I am now level 14 and I have a rocket launcher that barely does 1000 damage, am I ready to face him?
Comment: Welcome to Arqade. You should only post one question at a time. If your want an answer to your second question, you should make another post
Comment: The game offers you a hint about this for everything you encounter:  If there's a little skull by its health bar, the game thinks you should run!
Answer: While I can not answer your question directly, here's some advice.
Get a sniper rifle or an accurate launcher, and feel free to stay away from W4R-D3N, picking at his eye from afar (from the middle or from the left). This way you won't get swarmed by bots and will still kill it eventually.
EDIT: Considering W4R-D3N's shields, as well as obviously bringing shock weapons, one can use "speshul tactics" - when engaging Loaders, do not let constructor's shields go up by sparing a bullet every 5 seconds or so - you don't need to do any considerable damage, just register a hit. This is, of course, easier on a mouse...
AFAIK, all corrosive weapons can cause corrosive damage over time, if this is what you mean by "acid burn". They can be found aywhere. But do not think that corrosion is a must, an explosive or an accurate physical weapon will still do.
Comment: I disagree about a corrosive weapon not being a must - corrosive weapons deal 150% damage against armored targets, like W4R-D3N. A shock weapon (for his strong, regenerating shields) and a corrosive weapon (to melt the metally nougat center) are both recommended.
Comment: I did not recommend against corrosive. What I meant is +50% is not a gamebreaking bonus. Oftentimes I'd choose an physical sniper rifle over a decent corrosive SMG or an auto pistol - reliable criticals from afar are better than moving up close or hitting constructor's hull.
Answer: The WAR-D3N, like all Constructors, is crazy hard to kill unless you hit his eye. I noticed this while trying to kill Constructors with Corrosive DOT with an SMG. It took forever until I shot it in the eye a couple times...suddenly they were easy. Just shoot they eye; the problem is the eye is their crit spot, and everywhere else on their body is resistant to damage (even corrosive isn't great unless it hits the eye). I don't actually recommend using launchers against WAR-D3N, since they can't critical hit.
As far as level, you should be no more than 2 levels below WAR-D3N's level; the damage you and enemies take is scaled directly by level (there's no hidden stats, it's a %), so if you're 5 levels below WAR-D3N he'll deal insane damage to you, and vice-versa if you're over-leveled you'll easily slaughter him.
Comment: I've successfully used a corrosive auto pistol with a stupid, but fun tactic - run right up to a constructor's eye, drop to your knees, spray and pray his health runs out faster than your time :)
Answer: I would recommend lvl 14 or 15 with shock, corrosive, and explosive weapons. Orc JMR stated that the left or middle are good places to kill it.
The best place is the middle, where no attack can hit you.


Export posts manually selected by end user (not logged in)

Question: For an intranet project, I'd like to have not logged in users be able to manually check posts (with checkbox in front of post title on archive page) and be able to export some predefined data about those posts (ex: title, date, author, acf field...) in a format (json, csv...)
I'm quite new to Wordpress development, can someone points me to some direction or resources?
Thank you
Answer: I would recommend doing it mostly in Javascript:
Basic steps (pseudo code):

On the archive page add check boxes <input type="checkbox" name="post-with-id-1" value="1"> next to each post and a submit button <input type="submit" value="Submit"> at the top or bottom of the page.
In js, listen for clicks on the submit button.  When it is clicked check which checkboxes are checked and create an array of post ids.
The simplest thing to do then would be to build a url that opens a page in the browser from the REST API like this http://demo.wp-api.org/wp-json/wp/v2/posts?include[]=470&include[]=469  where you append an 'include[]=470' for each of the selected posts.  That url will build JSON Array that includes object representations of each of your posts.


Maple plant that will not turn green?

Question: I live in Ireland. I bought an Acer plant "deshojo" ,few years back . Now I have two issues with this plant. One is that it will give that nice pink/red color only for few months (April -june). The rest of the year its almost green, which i don't like.The second issue for me is that , there is possibility of this plant becoming big for my small garden.So i am going to replace this Acer plant with a new Acer Variety So can someone help me to find an Acer plant that's Dwarf (max 8-9 feet) and may not turn to green (a variety that may convert from red-pink-red or red-orange-yellow) and will survive in Ireland Thanks in Advance
Comment: How large of a Maple would work for you?  Having a tough time understanding having a problem with green.  A tree that changes color during the growing season is a plus.  What do you have going for a landscape where green would be a negative?  There is Acer ginnala...a small multistemmed tree or a large shrub, pruned  to thin for a small tree might fit your bill.  Very very colorful in the fall otherwise, you are looking at beautiful trunks, green canopy great to use to create an outdoor room with walls and a roof...gravel floor?  Green becomes part of the tapestry of your landscape.
Comment: Then there is my favorite tree of all: Amelanchier alnifolia multi trunked...small 'patio' tree with 4 season beauty.  Rare for trees btw.  First to flower in the spring followed by lovely reddish, green smallish rounded leaves.  These leaves change from reddish, purplish to light bright green and then to a dark steady green.  Yummm.  This tree produces berries you can eat IF you are able to harvest them before the birds do.  Black berries.  Dove gray smooth bark.  Gorgeous branching and winter beauty.  Almost no insect or disease.  And would do very well  as a small grove in Ireland...
Comment: I am look for a tree that may grow max to 8-9 feet. I think there are few varieties saying dwarf Maples (caperci dwarf is one of its kind). Color change is good but, if the color change from pink to red or orange or yellow will be better than green as all other pants in my garden are green.
Comment: What the cool thing about green is that it becomes part of a tapestry.  A PROFESSIONAL design will keep most factors; rhythm, color, texture, shape...the same.  Then like fireworks the garden changes through the seasons.  The worst thing people who do not understand art, aesthetics, landscape design rules do is to buy one of everything and nothing at all is similar.  Everything becomes a 'specimen' plant or a 'focal' point. Humans have a hard time with any incoming stimulus that is greater than 3.  If everything is a focal point you will have chaos.  Uncomfortable, unmanageable...
Comment: There is a very big power in mass of one color.  Soothing, understandable, (you won't know why you are uncomfortable in a chaotic setting but I do...grins)...I just gotta know more about what you are trying to achieve.  You do know that I am a Landscape Architect, yes?  Free advice?  Please, send pictures and more information.
Answer: The Acer palmatum variety you already have is actually described by the RHS as turning green within a few weeks of the leaves opening, but perhaps you did not find an accurate description prior to purchase. This is not uncommon - Acer palmatum 'Beni-maike' starts out red, turns a glorious pink and then, unfortunately, green within the first 6-8 weeks after leaf break, so if you want one that maintains its colour throughout the growing season, a careful choice has to be made.
There are others which more or less hold their colour until autumn and which don't get so large as the one you currently have, such as Acer palmatum dissectum 'Garnet', or Acer 'Crimson Queen'. Acer 'Bloodgood' holds its colour well, but gets larger than the size you've specified. Info here re Acer 'Garnet', and you can use the search box within the link to check out the other Acer I mentioned - be sure to check the height and spread measurements towards the bottom of the page for each https://www.rhs.org.uk/Plants/231/i-Acer-palmatum-i-Garnet-(D)/Details. It is much better to choose one that gets the size you want, and not one that gets too large and which you have to constantly prune back - that repeated pruning destroys the line and shape of an Acer palmatum variety, and frequent pruning is not recommended.
Comment: rhs site helped me to find the answer, Thanks.
Answer: Few I found are given below.

Acer palmatum 'Inaba-shidare'
Acer palmatum 'Ornatum'
Acer palmatum 'Garnet'
Acer palmatum 'Dissectum Atropurpureum'
Acer palmatum dissectum 'Lace Lady' Tree
Acer palmatum dissectum 'Crimson Princess' Tree

and atlast the one i selected is 'skeeters broom'
Answer: I am afraid the color of the plant is part of its genetics and might be influenced by seasons.
About your becoming too big problem. Acers are ideal for bonsai!
There is also a purple Japanese Maple (Acer palmatum atropurpureum), which you can keep small by pruning. This variety stays red throughout the year, but should be planted in shade/half shade (in full sun the leaves will burn in summer, making them the kind of yellow you don't want).
Comment: Sorry .I think you misunderstand my question.My doubt is to find a new acer plant replacing current one as I have two issues with this. I have edited my question to avoid confusion

Maple plant that will not turn green?


Is there a rigorous probability theoretic formulation of linear regression

Question: Let $(\Omega,\Sigma,P)$ be some probability space and let $Y: \Omega \to \mathbb{R} $ be a random variable. Let $x, \beta \in \mathbb{R}^n$. In a linear model we assume something like this: $E(Y|x)=\beta^Tx$. I know conditional expectation, where you condition on either an event $E \in \Sigma$ or on a sub-$\sigma$-algebra $\Sigma' \subseteq \Sigma$. As a special case of the latter, we can condition on another random variable. But the variable $x$ is not random, so how would you rigorously define $E(Y|x)$?
Comment: You can condition on $X = x.$
Comment: But what is $X$?
Answer: The typical way linear models work is to assume that $Y = \beta^T X + \varepsilon$ where $X$ is some random variable that we believe is related to $Y$ and $\varepsilon$ is another random variable independent of $X$, and $\beta$ is constant (i.e. deterministic), but possibly unknown.  For example, $Y$ might be a person's weight and $X$ might be a person's height.
There is a theorem that states that (under certain conditions) there exists a measurable, deterministic function $f$ such that $\mathbb{E}[Y|X] = f(X)$.  One can then define $\mathbb{E}[Y|x] = f(x)$ to avoid conditioning on null events like $X = x$ when $X$ is a continuous random variable.
Comment: Thx! Two questions here: 1. People often say that the variable X is not random in the linear model. Are they wrong? 2. Can you maybe give a reference for the theorem?
Comment: Ah you probably mean the Doob-Dynkin Lemma, right?
Comment: 1. I'm not sure I've seen linear models where $X$ is not modeled as a random variable.  One often tries to estimate the unknown parameter $\beta$ from some _observations_ of $X$, which are not random.  After estimating $\beta$, one can try to estimate an realization of $Y$ from a realization of $X$, and that realization of $X$ can be thought of as deterministic, but generally the underlying model includes a random variable $X$.

2. It's a consequence of the Doob-Dynkin lemma, sorry, I forgot the name.
Comment: Thx, I think I am happy now. I still have some problems with the words estimation / estimator, which seem to have different meanings in different contexts but that's another story ;)
Answer: There are several models that can be called "linear regression."
The most straightforward model is to assume we have $p$ $n$-vectors $X = [x_{(1)}, \ldots, x_{(p)}]$ and a "response" $y$ in $\mathbf{R}^n$ both of which are known, and we want to obtain the projection of $y$ onto the span of $X.$ There are no probability assumptions here.
A second model is to assume $(Y,X)$ is multinormal and then $E(Y \mid X)$ is linear. Here we explicitly assume $(Y,X)$ follow a particular probability distribution.
The third is to observe that for $L^2$ random variables, $Y = E(Y \mid \mathscr{H}) + (Y - E(Y \mid \mathscr{H}))$ and we see that $E(Y \mid \mathscr{H})$ is the orthogonal projection of $Y$ onto $L^2(\mathscr{H})$; when $\mathscr{H} = \sigma(X),$ then $E(Y \mid \mathscr{H}) = E(Y \mid X) = f(X)$ for some (deterministic but unknown) measurable function $f$; often we approximate linearly $f(x) \approx \beta^\intercal x$ and then we recover Ordinary Linear Regression. Here, we only need that $Y$ has second moment.