How to install Ranorex studio in ubuntu (linux)

Question: Ranorex studio is an automation tool but i can only install in windows how to install in ubuntu
Answer: Ranorex is a Windows only application thus you cannot install it on Linux or macOS.
You could install Windows in a virtual machine, for example with VirtualBox and the free 90 day testing images of Microsoft. Now you can install Ranorex in the virtual machine.


Digital Alarm Clock

Question:
Most of the alarm clock's bulbs are busted as shown above in black shades.
 Although still working it is not possible to tell what time is it. If we can
fix it to display a pattern every seconds, maybe it will be possible to tell time.
How can it show the Hours,Minutes and Seconds of the day in 12H format?
Comment: Not sure if I quite understand the question. Are you saying that the only LCD segments which work are the ones forming the two "8"s either side of the right-hand colon, and the colon itself? What about the "SAT" and "PM"?
Comment: note.We cant fix the busted bulbs
Comment: @randal'thor-  we can leave them they are working properly
Answer: If I'm understanding the question correctly, the only working segments are those forming the "8"s either side of the right-hand colon, together with this colon itself:

Each one of these segments can be switched on and off if required, but the broken segments can't be fixed. Since there are 16 different working lights and 2 different settings for each, the total number of possibilities we can display using the clock as shown is $2^{16}=65536$.
But the number of possibilities for the time of day in hours, minutes, and seconds, shown using the 12-hour system, is $12*60*60=43200$. This is less than $65536$, so we can display all possible times of day using only the working segments of the clock.
Comment: What time is it in your design?
Comment: So if I understand correctly, you assume that the AM/PM display still works? -- Ah, indeed, OP says 12h format. Also, you missed some braces in 2^{16}.
Comment: This only works if you can control the two parts of the colon individually, right?
Comment: @TSLF The segments shown would indicate a value outside of the 43200-second range.
Comment: If we want to make it readble  , we can  use the perimeter of 8 that is like 0- bothe side for the minute and seconds  while the colon dots and the center element of both 8's for the  hour  - [ 0] [ -:-] [ 0]  for  MM:HH:SS , w/ combininations:( 2^6) (2^4) (2^6) =(64)(16)(64)
Answer: The clockwise sequence patterns for 12-Hours and 60-Min/Sec

Digital Alarm Clock


How do both sides know the MTU

Question: If I have ComputerA that has their networking interface set with an MTU of 1500 and ComputerB has a network interface with an MTU of 1200 is there any way for ComputerA to know that ComputerB's MTU is 1200 or if it sends large packets it will get from ComputerB a request to fragment the packet?
Comment: Possible duplicate of [What does MTU depend on?](https://networkengineering.stackexchange.com/questions/57206/what-does-mtu-depend-on)
Comment: @Zac67 That talks about the protocol but does not answer my question.
Comment: Did any answer help you? If so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you can provide and accept your own answer.
Answer: The hosts can use Path MTU Discovery which is optional for IPv4 and mandatory for IPv6.
With IPv4, a packet is fragmented where it is larger than the egress interface's MTU - that can happen on the source host or any intermediate router. In your example, the router between A and B would fragment the packet.
Fragmentation can put considerable load on routers and was removed for IPv6 routers, so a v6 host needs to discover the path MTU for each destination or fragment oversized packets by itself. If an IPv6 router encounters an oversized packets it returns an ICMP error and drops it.
The MTU is a property of each interface. It is either (hardware) default, configured statically, or by DHCP (option 26). All nodes in a shared L2 segment need to use the same maximum frame size, resulting in the same MTU. If a node sends larger frames than the others can except these are dropped as oversized.
Comment: PMTUd only works where there's a router between the mismatch. It does nothing on-link -- a packet larger than MTU is an error (oversized) and dropped without the OS even knowing about it.
Comment: IPv6 also has fragmentation. However, it's the job of the end-points to do the framenting, vs. the IPv4 process of the router-in-the-middle doing it.
Comment: @RickyBeam All hosts in a common L2 segment need to use the same MTU. If they differ, packets are lost, as you've said. Re fragmentation: you're correct, of course - added, thx.
Answer: This is a bit of a sideline answer, as the question was about MTU, not MSS.
... and then there's TCP MSS, which helps in case of TCP, but of course not with UDP nor ICMP.
Using the MSS field in the TCP header (only in the SYN and SYN-ACK packets of the initial 3-way handshake), hosts can signal to their peers how large a TCP payload is acceptable to receive.
TCP MSS negotiation can be a blessing, but also a nuisance, as it helps to hide MTU problems until something with large UDP packets comes along and fails at the "all hosts on the common L2 segment need to use the same MTU" criterium (see Zac67's comment, above)
A host will derive the MSS from the MTU of the given egress interface used to communicate with the given peer. Usually, values of MTU-40 are seen (1460 for common ethernet), or even less if TCP timestamping is being used.
TCP MSS is a property of the given TCP session/socket; a jumbo frame enabled host will happily exchange TCP segments with a peer which has 1460bytes MSS just as well as one with 1160 bytes, while talking to the a backend system with an MSS of 8960 bytes, all simultaneously on the same single interface.
If the network path between the TCP speakers has tunneling features (such as an IPsec site2site-tunnel), routers, gateways or firewalls will often manipulate the TCP MSS field in the initial packets of a TCP session (usually to something like 1350 bytes); this is known as "mss clamping" or "adjust-mss", to make the end systems believe that the reciprocal remote peer could not receive larger packets, which would not fit through the tunnel without fragmentation (of course, if a host signals an MSS lower than the clamping value, the device will leave the lower value as it is)
Comment: ... and MSS negotiation miserably fails when a link in between has a lower MTU and doesn't clamp. This is probably one of the reasons to make pMTU discovery mandatory and do away with all the patchwork.
Comment: @zac67- you certainyl have a point there. However, I'd rather strive for proper MSS clamping implementation than to hope that end hosts, together with multi-level-encapsulating router cascades being hampered by icmp-averse firewall admins will eventually get PMDUd right...

How do both sides know the MTU


Is the ring smaller than normal in the Rocky movies?

Question: I was watching Drago pummel Apollo Creed in Rocky IV and it seemed like the ring was smaller than a regulation ring. Normally, pro rings are 18x18 or 20x20, but the ring in Rocky IV seemed a lot smaller than that. Am I imagining things or did they use a small ring for cinematic purposes?
Comment: Did the Russian ring look smaller as well? Could be in-universe the Creed/Drago ring was smaller because it was an exhibition match.
Answer: Boxing rings vary from 16 to 24 feet per side, depending on the fight level and what the promoter of the fight wants.  Amateur fights take place in rings 16 to 20 feet per side, and professional fights take place in rings 18 to 24 feet per side.  Given that it's an exhibition, it could be fought in any ring between 16 and 24 feet per side.  I can not find any specific information on the Rocky IV movie, but you have to figure that both Creed and Drago stand taller than 6 feet.  Put them in a smaller ring, say 16x16, and that ring is going to look tiny.
Seeing as the promoter of the fight between Creed and Drago was Rocky, who was also Creed's trainer, it would seem odd that he would choose a smaller ring which gives an advantage to the taller Drago and his extremely dangerous 1,800 PSI punch.  So, that part of the movie would probably be counter to a realistic match.
Sources:

Wikipedia article on Ivan Drago
Article on boxing ring dimensions
Comment: Yes.  Sorry, I had a Spinal Tap moment.  I can now see Midget Wrestling in my head...
Comment: Are you sure about that math? 16 square feet would be a ring that's 4 feet by 4 feet, a ring that's 16X16 would be 256 Square Feet. I'm guessing that you meant 16 - 25 feet to a side...


Gradient Descent Convergence

Question: I'm a double major in Math and CS interested in Machine Learning. I'm currently taking the popular Coursera course by Prof. Andrew. He's talking and explaining Gradient Descent but I can't avoid noticing a few things. With my math background, I know that if I'm trying to find the global min/max of a function, I must first find all the critical points first. The course talks about convergence of GD, but is it really guaranteed to converge to the global min? How do I know it won't get stuck at a saddle point? Wouldn't be safer to do a 2nd derivative test to test it? If my function is differentiable it seems reasonable it converges to a local min, but not to the global min. I have tried looking for a better explanation but everyone seems to take it for granted without questioning. Can someone point me in the right direction?
Answer: Gradient Descent does not always converge to Global minima. It only converges if function is convex and learning rate is appropriate.
For most real life problems, function will have local minimums and we need to run training multiple times. One of the reason is to avoid local minima.
Answer: If you use a version called Backtracking Gradient Descent, then convergence to one single local minimum can be proven in most cases for most functions, including all Morse functions. Under the same assumptions, you can also prove convergence for backtracking versions of Momentum and NAG. More details can be found in my answer and the cited paper, as well as link to source codes on GitHub, in this link:
Link
Answer:
The course talks about the convergence of GD, but is it really guaranteed to converge to the global min

This course talked about a case of simple MSE which is a Convex function. For a convex function,
"Yes" it is guaranteed.
In other scenarios, it is not guaranteed. That's why we have a bunch of optimizers.
In simple ML algorithms space, you will not need these.
If you start Deep Learning. You will have to learn that. Andrew NG has a great Coursera course on Deep Learning too.

Using Maths to get Minima/Maxima

This will become next to impossible when you have 1000+ parm (A Neural network, millions in case of CNN). Loss function would become way too complex to achieve that task i.e. A complex function of Millions of variables.

Gradient Descent Convergence


What are the outcomes of killing and sparing the Shaelmaar?

Question: The game gives you the option to kill the Shaelmaar.
Normally that kind of option would influence the outcome of the story somehow.
In the Shaelmaar's case, does it influence the story? Do you get any reward whether you kill him or not?
Comment: Probably it does. In the Witcher, almost everything has an effect. Load back from a save and try the other way ... have fun and experiment!
Comment: Bryan, my question is more about how the action will influence the game and less about the reward from killing the beast. I know I mentioned the reward at the end, but just for curiosity. The main question is about how it will change the history.
Comment: I just let him live straight out of principle. What Geralt says is right, it's only there to be slain so that the crowd can be entertained. It isn't a threat to humans.
Answer: If you spare the Shaelmaar you will get one of five virtues.
The virtue that you get is Compassion.
There is one side-quest ('There can be only one' Quest) in which you must have all the virtues. (I won't spoil anything).
So all-in-all, you sparing the monster won't have any immediate effects or any large repercussions, since Compassion is one of the virtues you can get in another situation in the DLC.
Just FYI and to feed curiosity the virtues are:

Generosity
Valor
Compassion
Honor
Wisdom
Comment: Thank you! I was sure that "timed dialog" wasn't there by accident!!! Thank god I spared the creature!


"Dabei geht es um" vs "Es geht um"

Question: I have come across both phrases at the start of sentences, and both apparently have the same meaning. Is there any difference between the two? Can they be used interchangeably?
Comment: You may have noticed that the phrases differ in that the first uses "dabei". Did you check what this word means? Because this may answer your question.
Comment: »Dabei geht es um« = »Es geht dabei um« ≠ »Es geht um« (no »dabei« in the 3rd phrase)
Answer: It means almost the same with the difference that the first version refers to something ("dabei") and the second version does not explicitly refer to something ("es" is more generic).
Answer: In English it could be translated as "This is about..." and "It is about...", so it means basically the same, but with a slightly different construction.

"Dabei geht es um" vs "Es geht um"


Should I retake GRE?

Question: I took the GRE two times, and unfortunately, I could not improve my score on the second attempt. I considered applying with my current GRE score which is 160Q and 140V.(Ps. English is my second language and the verbal part if helpless for me. I do not think that I can improve my verbal score; however, I can make the Quant better.)I am so confused about retaking the GRE a third time. Any suggestions for me?
Comment: Perhaps these types of questions (standardized tests as they relate to admissions) warrant a sticked or meta question?
Comment: You've taken it twice with similar results -- why do you think a third attempt will be better?
Answer: thanks for joining the site. Others have asked similar questions here, here, and here (all relating to standardized tests and scores). You might also benefit from a general discussion about admissions decisions. There is a general consensus is that test scores are only one component of an application. You might consider focusing on a supplementary letter explaining the lower verbal score or focusing your efforts on other assessments of language (such as the TOEFL, if required).

Should I retake GRE?


Picasa photos in gallery don't show up in photos app or google+ photos

Question: I have some photos that show up in gallery>picasa, but not in the photos app. I know these photos were downloaded pictures from a previous phone, off a received email I believe. I may or may not have deleted them before on the google+ photos list on the web. After switching to a new phone with the same SD card, they are still there, unable to delete in gallery because they supposedly come from picasa web. Please help.
Answer: Look here, they are all the photos  uploaded into your account. you can also check this. If they are on either site, they must also be visible in google photos app (if you are connected to the internet). Don't forget to turn on sync all photos in the google photo app, aftewards they will show up or they do not exist.


What makes a language more suited to Artificial Intelligence?

Question: I've always read that LISP is well suited for Artificial Intelligence, but I never found out why.
Answer: I believe it was originally based on the idea of the program being able to learn by modifying its own code to represent the new intelligence. Lisp makes that relatively attractive by representing programs as S-expressions -- i.e., a "program" is just ordinary data that's interpreted as code to be executed, but can also be interpreted as data to be manipulated about equally easily.
That said, that notion of the program modifying itself to represent new knowledge as it learns doesn't seem to be put into real use particularly frequently.
The other obvious point is that "artificial intelligence" isn't particularly well defined. If you look at books from the '50s or '60s about artificial intelligence, most of them talk about problems (e.g., recognizing handwriting or speech) that are now rarely considered as AI at all. The meaning of "AI" seems to be in a state of (nearly) constant flux. When somebody figures out practical way of doing something, it becomes normal programming rather than AI.
As such, AI programming tends to be rather exploratory and the code in a state of flux itself. As such, the answer to the question in the title is that AI tends to favor languages that support a more exploratory style -- dynamic languages with minimal type checking, interpreted or compiled only implicitly, etc.
Comment: It's like music, there's a new kind of music which is experimental, some time later it's mainstream.
Comment: I've read that this artifical inteligence was atributed to functional languanges like LISP, then now I guess it's not about functional programming but about metaprogramming. Or is metaprogramming an obvious implication of functional programming?
Answer: All languages have different usage. and while you might have heard of Lisp (or prolog, haskell as well) being popular.
The point is they are declarative languages and there is general idea that Knowledge representation can be better and more effective using declarations of axioms or rules as opposed to expressing them as algorithm and linking them in all possible context of evaluation.
It is not a universal practice that you cannot use imperative languages there.
Answer: I've read this and it might give you the context from this comes from: http://www.rci.rutgers.edu/~cfs/472_html/Intro/MinskyArticle/MM1.html
Also i must add that even if LISP doesn't feel "useful", it's a nice thing to at least try once or twice.


What kind of pipe nipple to use on my well pitless adapter

Question: I am working on the water pipe that connects to the pitless adapter on my well casing.  There is a 1 in black pipe nipple that is screwed into the brass female thread of the pitless adapter.  I have a threaded pvc coupling screwed on to the other end of the nipple.  The pipe nipple developed a hole in it and started leaking.  So, now it needs to be replaced.  I guess I could just extend the pvc and screw a plastic fitting directly in to the pitless adapter, but I am of the opinion that I still want a metal to metal connection at the pitless adapter.  I am considering a 1 in x 3 in or 1 in x 6 in brass nipple.  Those are not impossible to find but not easy either.  Any thoughts?  Thanks
Answer: I just recommend using brass fittings for all of that stuff.

1" brass close nipple
1" FPT x 1" Brab brass female insert adapter

If you can't find a female insert adapter, you can basically make one using a 1" female-female coupler + 1" male MPT x 1" Barb insert adapter.
Should look something like this (though don't forget to use stainless steel clamps on the pipe, which this guy hasn't put on yet):
Answer: Stainless steel, brass (I'd suggest surface-treating for free lead before use) would both be a better choice than black iron, which was a dielectric bad move on someone's part. Though I'd expect the pitless to be bronze rather than brass...
Shippable well parts are often easier to find on-line than locally, especially if they are out of the ordinary materials-wise. I've never seen stainless nipples in a store, but they can be had online easily enough.
If you are going to PVC threads, I'm not sure that a metal-to-metal connection at the pitless buys you anything, since the plastic threads can still snap 3 or 6 inches away and drop your whole string down the well. But I'm habituated to metal threads on a barbed adapter double-hose-clamped to 160 or 200 PSI polyethylene pipe going down-well, so that's mostly just fear of a system I've never used and some experience with PVC stress-cracking as it ages. I suppose its possible that a female-threaded plastic fitting might be a little more sturdy than a male-threaded one.


Is August 15th a day of obligation for all Roman Catholics?

Question: August 15th on which the assumption of St. Mary, mother of Jesus is commemorated by the  Catholic Church is a day of obligation for the Roman Catholics in India. I wish to know if the day is one of obligation for the universal Catholic Church, or is the practice restricted to India which commemorates its independence from British rule on the same day ?
Comment: Of the ten holy days of obligation mentioned in the Canon Law all but two have been suppressed by the Indian Bishops Conference, leaving only the Assumption and Christmas Day, both of which are public holidays, the Assumption being so only by coincidence with Independence Day, and Christmas in its own right. It is very likely that the Conference chose to retain the obligation on the Assumption, while relaxing it on other days, because  the public holiday makes it practical. Even some Catholic countries such as Brazil do not observe the Assumption as an obligation, but Catholics in the UK do.
Answer: The Assumption of the Blessed Virgin Mary is a holy day of obligation for the entire universal Church (Code of Canon Law, 1246 §1).
At the same time it should be recalled that the conference of bishops can suppress or transfer some holy days of obligation with the permission of the Apostolic See (Code of Canon Law, 1246 §2).
See also: What are the Holy Days of Obligation? (Catholic Answers)
Comment: Is the Assumption the highest form of offering, I think it's a Solemnity not a Feast, that's why it's an obligation.
Comment: It is a Solemnity, which is the highest category, but not all solemnities are holy days of obligation.
Comment: Solemnity are only given to Jesus, but thru Dogmatic teaching it was extended to Mary that's what I've heard from our priest.So all solemnity are holy days of obligation.
Comment: [Here](https://relevantradio.com/2017/12/2018-holy-days-obligation-solemnities/) is a list of solemnities.  You will see that relatively few are holy days of obligation. Honestly the language is somewhat fluid.


What is the definition of a pad?

Question: I've played in many bands and I do a lot of music production and the term "pad" is thrown around. My definition of a pad is something that is used to fill in the space of a piece usually with chords. However, I'm not sure if this is the official definition of a pad. I consider instruments like organs, strings and various synths to be pads. Perhaps it would help if the etymology of the word "pad" was known. I've checked several websites, but the answers to these questions are inconclusive.
Comment: I suspect there is no real definition as compared to say staccato, but would add choir sounds to the list you mentioned and also say that a slowish attack speed is characteristic of pad sounds as well as tying notes across chords changes.
Answer:
My definition of a pad is something that is used to fill in the space of a piece usually with chords.

This is pretty much spot on. Like the orchestra uses the string section to play chords, people use synth pads to fill in with chords. I'll borrow the wiki definition:

A synth pad is a sustained chord or tone generated by a synthesizer, often employed for background harmony and atmosphere in much the same fashion that a string section is often used in orchestral music and film scores.

But, these kind of pads can also produce sounds; not just chords. Like for instance:
Comment: So I guess we're on the same page. I saw that definition for synth pads as well, but then if there are synth pads, there must be non-synth pads as well.
Comment: In an arrangement you can use the term pad of course for the held chords  of strings or another section of instrument's  non rhythmic held chords. This would be a common analogy.
Comment: And here I thought the word "pad" had something to do with the console buttons that look like little pads. Silly me!
Answer: As you say, it's something that 'pads out' the mix to fill space.
Often the word 'pad' is used when talking about synthesized sounds, and refers to how a specific sound 'sits in the mix'. So you wouldn't really say that 'organs are pads' in general, because there are a lot of different organ sounds, some of which are very cutting upfront sounds (hence not 'pads'). But you could talk about an organ pad - a backgroundy, washy sound that had organ-like characteristics.
To some extent, a sound can be a pad because of how it's treated. Even a lead guitar sound could become a 'pad' if slathered in harmoniser, reverb, and delay.
Answer: The definition and history allows two derivation and associations that are covering our sensation when we are using the term pad and are congruent with  the answers we have already got:
So I try and additional answer:
A pad in music can be for instance a string pad or synth pad.
and now the association: something soft (soft pad) to lay on! The melody lays on the pad of the chords - (long) held chords.
*1550s, "bundle of straw to lie on," a word of obscure origin (perhaps a merger of several separate words), possibly from or related to Low German or obsolete Flemish pad "sole of the foot," which is perhaps from PIE pent- "to tread, go" (see find (v.)), but see path (n.).
Sense of "soft cushion" is from 1560s, originally a soft saddle. Generalized sense of "something soft" is from c. 1700. Meaning "cushion-like part on the sole of an animal foot" in English is from 1790. The sense of "a number of sheets fastened or glued together at the edge" (in writing-pad, drawing-pad, etc.) is from 1865.
https://www.etymonline.com/word/pad
for more information also see:
https://musicianshq.com/why-is-a-synth-pad-called-a-pad/
It cites the same wiki quotation we have already got.
At first it cites the same wiki quotation we have already got.
The interesting point is the definition asking:
What is the difference between a synth pad and a synth lead?
A good way to fully understand the definition of a pad is to contrast it with the type of synth sound at the opposite end of the spectrum. This is known as a synth lead.
Whereas a pad fills the space in the background of a track. The lead is very much in the foreground of the mix.
But now again my own sensation:
A pad is the  pillow or a carpet, the underlayment of chords (by strings or synths) for the  melody.

What is the definition of a pad?


Examples of measure zero sets in physics

Question: The problem with Riemann integration of functions like ${\chi }_{ℚ}(x)$ (a function  which takes the value of 1 if $x\in ℚ$, and 0 otherwise) is usually used to show the need for defining the Lebesgue integral. Since I don't have much practical experience with actual science and research, I have a question: are measure zero sets physically relevant (meaning that they are found as objects of interest among physicists or play an important part in some physical models), or are they used just to provide "pathological" examples and describe the need for some improvements in mathematics, like the Lebesgue integral?
Comment: Yeah, but so there's not one correct answer, there are potentially dozens of them. This is the definition of *too broad*. Not to leave you hanging though, look at $L^2$-spaces in quantum mechanics.
Comment: This question seems like a list question.
Comment: Not necessarily, I'm looking for just one good example. Of course, the more the better, but it's not obligatory.
Answer: In quantum field theory, one often considers meager subsets of the naively defined space of possible states. Indeed this is one of the Wightman Axioms: the Hilbert space of physical states is separable (has countable basis).
This is a manifestation of the intuitive assertion "we must only put a finite number of particles into a finite quantisation volume".
Just take a Fermionic Fock space for a finite quantisation volume, so that there are countably infinitely many plane wave as the "modes". Then an arbitrary basis member is of the form:
$$\left|\left.0,1,1,0,1,1,1,0,1,0,\cdots\right>\right.$$
that is, a countably infinitely long string of 0s and 1s showing which modes are filled and which are ground state. This set is mapped bijectively to the interval $[0,\,1])$ - its members are simply binarys expansions of numbers in $[0,\,1)$. So it's uncountable.
The "physical" states are those with a finite number of particles, so they are the dense subset $\mathbb{Q}_2\cap[0,\,1)$: the set of rationals in the interval with finite binary expansions. These are clearly a meager (zero measure) set.
You may also be interested in the Physics SE Question Separability axiom really necessary?
Answer:
are measure zero sets physically relevant (meaning that they are found as objects of interest among physicists or play an important part in some physical models),

They come up naturally. For instance if you study the actual dynamics of putting an eigenstate of $\sigma_x$ into a z oriented Stern-Gerlach device you'll see the Schrödinger equation predicts the upper half of the beam goes up and the lower half goes down (and that the spin state changes so that each branch has a spin that is an eigenstate of $\sigma_z$).
But what about the past of the beam exactly on the middle? It is a set of measure zero (its a surface in 3d) and so they happen with probability zero (which means they can happen but the expected frequency for lots of observations is less than any positive number).
And they come up in the regular pourtreal of square integrable functions (they they are only functions up to sets of measure zero).
But the latter example is a bit far fetched. For instance we could just start with, say, the energy eigen functions of the Harmonic Oscillator as a fine orthonormal set and then we can take their span and then take the closure and call that our Hilbert Space. Or even be explicit about how we take the closure and define the Hilbert Space to be the set of equivalence classes of Cauchy sequences of things in the span of the energy eigenfunctions.  And not that here we never ever need to bring up Lebesgue integration. The energy eigenfunctions are perfectly fine Riemann integrable functions they have a perfectly fine inner product and so we can have Cauchy sequences of them and then take two sequences to be in the same class is their difference is a sequence that goes to zero in the norm from the inner product.
We never had to do a Lebesgue interval, never needed measure theory, and didn't have worry about measurable sets.

or are they used just to provide "pathological" examples and describe the need for some improvements in mathematics, like the Lebesgue integral?

As you can see above the Lebesgue integral isn't an improvement. Historically the problem was that mathematicians simply made up some axioms that made it appear there were weird sets (think Banach-Tarksi decomposition) so they either had to give up their axioms and use other axioms or else learn to avoid those sets. So they made measure theory to avoid those sets. And then Lebesgue integration to use it. To make more functions integrable. But we didn't ever need to have so many functions in the first place. You can get the Hilbert Space with out worrying about the vectors in the Hilbert space being an equivalence class of square integrable measurable functions. They can be equivalence classes of Cauchy sequences of useful functions.
As a Hilbert Space they are equally good. You don't have to worry about weird functions. You can compute your predictions to any Kevel of accuracy without them and even have the same mathematical object (the Hilbert Space) without them.
Mathematicians say something is good if they can prove theorems with/about it using their favorite axioms and favorite deductive methods and sometimes if it uses their favorite theorems.
Physicists say something is good if it allows us to predict and understand the universe.
These two goals are not always the same. In fact, often they are not. Physicists might be more aware of the times when they match because of selection bias.
Comment: So, for most practical purposes (analysis of most experimental data) I don't have to worry about measure zero sets because in most cases I'm only interested in the normal convergence of my results to the predictions instead of uniform or pointwise convergence? After all, measurement results come with an error margin, so speaking of isolated points in the continuous distribution with a different / discontinued value doesn't make much sense.
Comment: Anyway, your answer is the most helpful and insightful one so I'll mark it as accepted.


As an intern, how do I deal with a supervisor who's not always there?

Question: I'm working as an intern in a software development role. My supervisor is working on systems or something similar, and is always busy. I never get to really see them. I mainly report my progress using demos/pictures of my work. How do I actually build up a relationship with my supervisor and get on his good side? It feels like we're getting off to a pretty bad start as everytime I try to go see them, they're not there.
Comment: Find out who you should be "taking direction from" in the manager's absence. There's usually either a team lead, someone who has been asked to work with you, or a "burndown list" of tasks needing to be addressed. If you can't find any of these, ask other folks in the dept what you should be doing until you can ask the manager.
Comment: Have you tried sending him a meeting request rather than just showing up at his door?
Comment: yep, used to, but he would send over a meeting request and then I would wait for it to start while working, and then the meeting wouldnt happen because they forgot about it or something and we end up not meeting, after this happened a couple times, i've sort of given up
Comment: If they forget the meeting, because they're engrossed in their work, just come knocking on their door a couple of minutes after the planned start.
Answer: Basically, you make his life easier.
To extend on that, he has some very intensive work that is consuming his focus. You can build rapport with your boss by alleviating the minor, time consuming tasks that you are capable of handling without being asked (in addition to your normal workload), which saves him time, and as long as it is apparent that this is due to your work (without bragging overtly), then he will like you. This will also very likely lift some of his time burden, which will give him enough time to actually engage you in normal sociable terms.
Comment: i.e. "I saw you had ____ on your plate and haven't been able to get to it, so I went ahead and took care of it when I had a little down time. I hope I wasn't overstepping my bounds."
Comment: I agree with you mostly. The only thing I would say is that you better be absolutely sure that the task you perform to assist the manager is something that you won't be causing problems doing. This is generally true in all fields, but especially the case when it comes to software development.
Comment: That is true. The key if you are taking this approach is to start with the tasks that are trivial, but time consuming. In software development, debugging css would be a good example, as it is pretty straightforward and doesn't damage underlying services or data, but is still time consuming. Tickets that have been left in the queue for too long are also fair game, as long as they are within your skillset.
Comment: However one should not overlook that this can also be as simple as grabbing an extra coffee when you go for one so your boss doesn't have to leave his desk and forget what he was doing.
Comment: While the advice is good for a normal employee, keep in mind this is an intern. Most intern's require a lot of direction on even the most simplest of tasks, let alone to figure out ways to help the boss on their own. I don't blame the intern, they are inexperienced and usually very nervous about screwing up, which inhibits taking the initiative to do as you are suggesting. Probably rightfully so. Thus, I'm not sure this is helpful in the OP's case. I do not recommend the coffee idea at all. You aren't hired to be wait staff, don't perform actions that would cause others to view you as so.
Answer: Ask your supervisor to have lunch with you. Let him/her know you understand they are really busy, but that you would like to get to know them a little better and hear about some of the other projects going on in the company.
What's the worst that can happen with a request like this? Even if it takes a while to get on the calendar, it's hard to imagine anyone too busy for something like this.
Answer: The priority is to have ONE meeting with your supervisor to talk about this issue. Make it happen. Offer to meet him at lunch time, to stay a bit later one evening... Insist on the fact that this is really important and will make both of your jobs easier in the future.
During this meeting, you'll want to discuss two topics :

How to interact with him : tell him you know he's a very busy man, and you'd rather find an efficient way to communicate rather than bothering him at random times. This can be a daily five minutes stand-up meeting, a weekly presentation associated with a progress recap email every evening...
What to do when you can't interact with him : him being busy doesn't change the fact that you're an intern, and thus need to be closely managed and taught. If he can't do that himself, have him introduce you to the people you can turn to about technical difficulties or whatever.

Anyway, don't forget that as your supervisor he's expected to make time for you. You're not a developer yet, there's a lot you have to learn, and him making efforts to help you improve is beneficial for both of you. Don't feel guilty for requiring attention or see yourself as a burden. Well let's face it, you most likely are a burden at the time. But one he signed up for :)


Is the hostname case sensitive?

Question: Is the hostname case sensitive? Is
ping MYHOST

equal to
ping myhost

Does it depend on the DNS used? Are there differences between Win/Mac/Unix systems?
Comment: Here is a RFC.  http://tools.ietf.org/html/rfc4343
Answer: Names resolved from DNS are case insensitive.  This is important to prevent confusion.  If it was case sensitive then we would have eight variants of .com (.com, .Com, .cOm, .COm, .coM, .CoM, .cOM, and .COM).  Country codes would have four.
If name resolution is case-sensitive for Ping it is not being done by DNS.
Comment: @Zoredache: It appears the internationalized domains using the IDNA system must be encodable in Punycode, which involves translation to lowercase.  There are also additional restrictions to ensure the names are visually distinct.  Also you don't want to force users to ensure they get the case right.
Comment: It does apparently get somewhat tricky after Internationalized Domain Names where added.  In non-ASCII contexts case may matter.
Answer: I've just had this here at work.   DNS should be case insensitive.... the RFC (RFC 4343 - Domain Name System (DNS) Case Insensitivity Clarification) specifies that but doesn't say it MUST be lower case.
So we had the pleasure of troubleshooting a host that didn't resolve things right for our internal domain  "t.local"
p123$ ping p123-db.t.local
PING p123-db.t.local (192.168.106.175) 56(84) bytes of data.
....works ok

p123$ ping P123-dB.T.lOcal
ping: unknown host P123-dB.T.lOcal

Why bother resolving the mixed case?  Because that's what tcpdump was showing as the DNS query because that's what the running software was asking for.  pgbouncer was configured to use "p123-db" in its config, and resolv.conf specified a search domain of "t.local"   So what is mixing up the case?
Turns out glibc was toggling the case randomly.  The process is called "0x20 padding" and was first described in 2008 in
"Use of Bit 0x20 in DNS Labels to Improve Transaction Identity"
https://datatracker.ietf.org/doc/html/draft-vixie-dnsext-dns0x20-00
The main purpose is to increase the entropy so that its harder to fake a reply - the question's case must match the case of the answer.
A good discussion may be found here.
https://developers.google.com/speed/public-dns/docs/security?csw=1#randomize_case

Separately, we run powerDNS internally, and that does lookups against a database.  For years, noone has used a hostname or FQDN in the t.local domain with a capital letter, so we never noticed that our internal domain was case sensitive.
Was fixed by some tweaks in the query, but this would have broken the 0x20 mixed case lookups as above - the client may require the answer is returned in the same case as it was requested.
Short answer:  DNS should not be case sensitive, but the question and answer will need to be identical case, in the future.
Comment: The answer 4 years after the question was asked, is subtly different.  I wonder in another 4 years will the answer be "yes - DNS is now case sensitive"
Answer: I just finished troubleshooting an issue on an embedded SE Linux device where host name resolution was exhibiting case sensitivity.
"ping MYHOST" would ping to 127.0.0.1, whereas "ping myhost" would ping the correct IP Address.
nslookup produced correct results for both uppercase and lowercase, indicating that the DNS server was not at fault.
But unlike nslookup, which ignores the cache, "getent hosts MYHOST" output "0.0.0.0", and "getent hosts myhost" output the correct IP Address.
So nscd is apparently case sensitive.
Calling "nscd -i hosts" to clear the cache fixed the issue.
The MYHOST in (uppercase) ended up cached with 0.0.0.0 due to a process trying to
establish a connection to MYHOST before the DNS entry was created, which happens when the remote device gets its DHCP assignment.
Answer: As BillThor mentioned, it's not case sensitive at the DNS or netbios resolution level.
The various OSes won't have a problem with the different casing either.
However, the applications may be aware of them.  For example, the web platforms on the various environments can check for case sensitivity.  It's more common now for search engine optimization (SEO) reasons to watch for different casing and redirect.  That's all up to the application though so the answer there is that it varies.
For the 'most part' the hostname isn't a case sensitive concern at the application level either though.

Is the hostname case sensitive?


how to resolve a chord progression that goes f#m d#dim

Question: This is probably a stupid question but I've been trying to resolve it for a while now and due to low knowledge of music theory, I can't. I don't really know what key I'm in.
Comment: Is this homework? In the key of E major, F♯m is the ii chord with a predominant function, D♯dim is the vii° chord with a dominant function. (It is the upper 3 notes of a B7 chord, which is the V7.) So... in E major you would resolve to...?
Comment: another way to solve this problem is to try out chords until you find something that sounds good...*THEN* try to figure out what is going on.
Comment: There aren't any stupid questions, never!
Answer: One way to do this is list out all the tones of the chords and then find a key signature they all belong to: D# F# A C#.
So follow the circle of fifths for sharp keys until you get a match...

1#: G/Em  - F#
2#: D/Bm  - F# C#
3#: A/F#m - F# C# G#
4#: E/C#m - F# C# G# D#
...

You should see that your set of notes matches E or C#m.
That's the 'mechanical' part of the issue, but now we get to the actual important part: there isn't a single answer to this question. Or, you might say it isn't answerable.
In E we could continue the harmony as ii viio6 I or ii viio6 V7.
In C#m we could continue the harmony as iv iio6 i6 or iv6 iio6/4 V7.
There are other possibilities.
You probably expect the answer to simply be 'it resolves to E major, because that 'resolves' the diminished triad treating it as the leading tone triad viio. But it's really wrong to think that is the one answer.
Comment: True. But, I only used the plain `ii` (`iv` in minor) because that was the chord in the question.
Comment: Beware of restricting yourself to diatonic chords in one key.   II7 V7 I is as common as ii7 V7 I.
Answer: A nice solution would be:
Starting in A :
A - f# - d#dim - A/E - E7 - A  -> I -vi - (vii°7) - I46 - V - I
d#dim would be a secondary vii°7 to A/E (I46) with the final E - A = V - I


Is this carbocation rearrangement possible?

Question: Is this rearrangement possible in carbocations?
Comment: @SR810 its fine whether it is or isn't a literal homework question, but you should include you thoughts on why you think it should/shouldn't occur and what research you have attempted to support that conclusion.
Comment: Possible duplicate of [Carbocation Rearrangement - Till which neighbouring carbon is it possible?](https://chemistry.stackexchange.com/questions/54634/carbocation-rearrangement-till-which-neighbouring-carbon-is-it-possible)
Comment: https://chemistry.meta.stackexchange.com/questions/141/how-do-i-ask-homework-questions-on-chemistry-stack-exchange    see that link once.
Comment: Not a homework question. Was learning about rearrangement , just thought if it is possible for something like this to happen
Comment: Oh! I was learning about rearrangements and saw 5 membered to 6 membered ring expansions. So I thought if 4 membered to 6 membered was possible.
Answer: I'd say it's almost surely impossible.
First of all, a carbocation on primary carbon is extremely unstable, so the question becomes how would you generate that. It is possible under some very extreme conditions, but then those conditions and the surroundings of the newly formed carbocation would be more controlling the reaction than the carbocation on its own. This newly generated carbocation would probably instantly react with solvent or with the leaving group thus reversing to the compound it was formed from.
Secondly, if we assume that the primary carbocation formed and this is some idealized situation where there are no other molecules around then the more probable scenario is that you will observe hydrogen transfer from the neighbouring secondary carbon, which would then undergo another hydrogen transfer, eventually forming a relatively stable tertiary carbocation.
Comment: What I was thinking was that formation of a 6 membered ring will reduce ring strain to a great extent hence making the carbocation more stable. So maybe in a reaction where the 4membered ring carbocation cation is formed as an intermediate  the product is formed as a result of the ring expansion into a 6 membered ring. Like it happens for 5 membered ring Carbocations.
Comment: When it occur in five-membered rings the carbocation the original carbocation is just next to where expansion take place - you can imagine it as if the carbon forming bond slid along the bond of carbocation and tertiary carbon; or imagine it with a transition state where all three carbons are connected by partial bonds. When it comes to rearrangements remember that the bonds don't actually exist like sticks holding atoms - a line is just a metaphor for two atoms being held close by the cloud of two electrons. But when there are more atoms around (and charges), this cloud can deform.
Comment: Anyway, if that is for your own knowledge then I would recommend you to forget about carbocation rearrangements and move on. There are beloved by chemistry professors because they can trip students, but they have almost none relevance in actual chemistry. All those primary carbocations from exams and tests exist almost only on paper. Only carbocations to actually care about are the stabilized ones - like tertiary, allylic, benzylic.


Problem starting Music app on iPhone

Question: When I turn on my music app, a picture of a girl wearing a headphone is showing and I cannot go to my music library. How can I resolve it?
Answer: The picture you're seeing is actually the page for Apple Music, it comes once you've updated the iOS to a relatively newer version supporting Apple Music. To get rid of that and proceed to your music library firstly make sure the phone is connected to the internet. Then open your music app. Once it's open at the bottom you should see a line saying either "No,Thanks" or "Continue to Music Library".
Just click on either one.
That did the trick for me when i faced this problem.

Problem starting Music app on iPhone


Should I increase my mempool size to accomodate temporary crisis?

Question: I am seeing 68k unconfirmed transactions on blockchain.info. My own bitcoind (v0.13.0) node has 49k transactions in its mempool with memory usage currently at 230mb. Knowing that the memory cap is currently at 300mb, I fear that very soon my node will not be able to keep all unconfirmed transactions. Should I increase this cap as a temporary measure until things get better? if so, how do I do that?
Comment: Related/possible duplicate: https://bitcoin.stackexchange.com/q/118137/5406
Answer: You can increase the mempool size, if you have an interest in seeing transactions that likely won't confirm for a very long time, but you certainly don't have to. The mempool is sorted by feerate, and when the limiter kicks in, it removes the lowest feerate transactions. Since miners sort by feerate, and can include only a limited number of transactions per block, the mempool effectively works as a queue.
By design, you will not always be able to store all unconfirmed transactions. If your goal would be to have all, and crank up your memory pool to accomodate this, someone could just start creating an infinite stream of transactions sending back and forth, until your node goes out of memory. This is the reason why the mempool size is limited in the first place: protection against a denial of service on the network.
Answer: You can change the maxmempool setting to achieve this.
https://gist.github.com/laanwj/efe29c7661ce9b6620a7
Comment: Please include the relevant information in your post, link only answers are considered low-quality and may be removed. If you found the information on another page, adding a link to the source is appreciated of course.


Suitable Engine Oil grade for my car

Question: I have Maruti Alto LXI model car. its odometer 96000km. can I know whats the most suitable engine oil brand and grade for this??
Comment: Have you checked the owner's manual or the workshop manual?
Comment: As Solar Mike says your user manual should tell you the correct type and grade of oil to use - if you don't have your manual then we might still be able to help but you'll have to give us a bit more information - namely the year of the car and which engine it has.
Comment: [This post](https://www.mycarhelpline.com/index.php?option=com_easydiscuss&view=post&id=10628&Itemid=78) answers your question.  See [this image](https://www.mycarhelpline.com/images/Engine%20Oil%20Grade.jpg) from the post for recommend weight for a given driving temperature range.
Comment: What is the year of the car? What engine does it have?
Comment: Manufacture year 2003, it have 800cc engine. I checked the user manual and there is mentioned 20-40W oil grade as the recommended oil grade by maruti suzuki. is it okay...??
Answer: As stated in the manual the recommended grade is 20W40 for that model and year.
Maruti Suzuki recommend various manufacturers oils - and offer co-branded versions under the following part numbers:
Castrol: 99999M20W40-CAS
Shell Helix: 99999M20W40-SHL
Total Quartz: 99999M20W40-TTL
Any of those will do the job.
Answer: Technically, the right grade of oil for any engine is the thinnest oil which will develop adequate oil pressure after start-up.  Oil pressure develops as the pump forces the oil against the surfaces the oil lubricates; the major contributors are the main bearings.  If the engine's bearing tolerances are relatively tight, pressure will develop with a thinner grade of oil than they would with bearing tolerances that are loose.  As the engine wears, the tolerances loosen, and then typically a heavier grade of oil is needed to develop adequate pressure.  The grade specified by the manufacturer takes this into account, as well as known manufacturing tolerances and variations, and then attempts to achieve a compromise which will both satisfy a brand new, unworn engine, and one that has tens of thousands of miles/km on it.  Since part of any motor vehicle manufacturer's goal is to improve/maintain their reputation for durability, an eye to this is given when specifying a motor oil.  They also want to minimize warranty claims, and maximize fuel economy.  Thicker grades of motor oil protect the engine better, but as they increase the work the pump must do, they tend to contribute to lower fuel economy.
In short, it's a compromise.  Read more: https://www.machinerylubrication.com/Read/518/motor-oils

Suitable Engine Oil grade for my car


Is the United States in a state of war with Iran?

Question: As of January 7, 2020, Is the US at war with Iran?
What is the litmus test to determine if the US is at war with Iran?
Comment: First of July 2020, or Seventh of January 2020?
Answer: No (assuming that nothing new as happened since I last saw the news earlier today, these matters can change in a matter of hours during the course of a day).
There has been no declaration of war by Congress (which has the sole power to declare war under the U.S. Constitution), there has been no authorization by Congress to use military force (the modern functional equivalent of a declaration of war), and Iran has not taken acts which by definition constitute an act of war that have been used to treat the two countries as at war (such as conducting prolonged mutual battles between military forces, as opposed to a single attack).

War does not exist merely because of an armed attack by the military
forces of another nation until it is a condition recognized or
accepted by political authority of government which is attacked,
either through an actual declaration of war or other acts
demonstrating such position.

-- Blacks Law Dictionary, "War" (5th Ed. 1979) (citing Savage v. Sun Life Assur. Co. of Canada, 57 F. Supp. 620, 621 (W.D. La. 1944)).
Thus, the fact that Iran appears to have fire missiles at U.S. targets, in and of itself (which the New York Times indicates as of 9:34 EST that it has) does not cause the U.S. and Iran to be at war. This story states that:

The Asad and Erbil bases were targeted by Iran in retaliation for the
killing of a top Revolutionary Guards commander in Baghdad.
American military officials said that Iran had launched more than a
dozen ballistic missiles against United States military and coalition
forces.

I am not aware at this moment, however, of any official reaction or statement regarding how this action will be classified by the United States, although that could happen very quickly before the day is out even.
What matters in determining whether or not the U.S. and Iran are "at war" is the meaning that is assigned to this attack by the President, cabinet members and senior military and diplomatic officials, and Congress.
Notably, being "at war" with a country does not mean, by definition, that the other country is "at war" with you. One country often becomes "at war" with another country at a different time that the second country comes to be at war with the first country. So, even if Iran's Parliament had declared war on the U.S, that wouldn't necessarily automatically and immediately cause the U.S. to be "at war" with Iran for purposes of U.S. law, even though a declaration of war in response would usually follow in short order.
@user6726 however, accurately and importantly notes that the isn't a single universal definition of "being at war" with a country that applies for all purposes. The correct definition depends upon the context and the purpose for which you are asking the question, and the consequences that flow from a determination that we are "at war".
N.B. One of the important reasons to know if you are "at war" or not, among others, is that an "enemy" for legal purposes, generally only includes someone you are at war with. Citizens or nationals of a nation with whom you are at war are "enemies" and have different legal rights that citizens or nationals of foreign countries with whom you are not at war.
Comment: There is a right held by sovereign nations to self-defense (e.g. under UN Treaties) and there is a generally recognized right of countries to engage in proportionate self-help retribution for violations of international law that impact a sovereign country, or its allies. It would be prerogative of senior political leaders in the U.S. to treat an attack on a US target as an act of war, if they interpreted it in that light, but it is not automatically an act of war. It doesn't become an act of war until senior U.S. officials make that determination which involves discretion and factual issues.
Comment: According to which law iran can attack those bases in iraq and kill US targets, isn't that war?
Answer: Congress has not officially declared war since WWII. We have "been at war" a number of times. There is a long legal analysis which exposes the nuances of the question, for example (start p. 49)
2 USC 198(b) says that the adjournment statute is not applicable in case of declared war:

This section shall not be applicable in any year if on July 31 of such
  year a state of war exists pursuant to a declaration of war by the
  Congress.

Since there is no declared state of war, Congress can adjourn. It really depends on what legal fact you are asking about. 10 USC 12521 addresses "a  period  of  war  declared  by  Congress  or  a  period  of  national emergency declared by the President or Congress" – as it happens, there are 11 current states of emergency in the US, most from the Obama administration. It just depends on what the relevant statute says.


PermitRootLogin No and Sudo user – Where is the difference?

Question: So, I've read that I shouldn't permit root logins by disabling them in my sshd_config. I understand how that might make a server safer, but if I have a user that is allowed to do "su root" and log into the server as root that way, what difference does it make? Seems like having a user that can log into the root user that way kinda defeats the purpose of the "PermitRootLogin" option.
Comment: `PermitRootLogin No` in the sshd_config, prevents someone to become root on another machine, because he or she has rights to do so and ssh'ing into your machine as root, even though their account doesn't have root privileges on the new machine. Yes it can be prevented by not allowing authorized key pairs to be stored etc, but sysadmins are absent minded sometimes and one temporary setting, forgotten to be removed can come back to bite you in the rear more often than one can imagine. So, having another layer of protection is not bad
Comment: Think about this. system1 can ssh into system2 as root and rootlogin is permitted in sshd_config. I have sudo privileges on system1 but not on system2 and think that it is for a good reason, like system1 being development and system2 being production. I can elevate my privileges on system1 and using the permitrootlogin backdoor, I can come to production system as root and try to fix a problem my code has caused, without leaving a trail. This is a big NO-NO by any type of auditing, SOX being the most widely known type.
Comment: Where does this multiple system idea come from? I'm running a single dedicated server.
Answer: PermitRootLogin No doesn't prevent root logins entirely, it only prevents root logins through ssh. Enabling this option prevents a class of brute force attacks where an attacker tries to ssh root@server with some common passwords (including an empty password, which can work if PermitEmptyPasswords is enabled). The point of refusing remote root logins is that root is a very common username; by disabling remote root logins you require the attacker to also correctly guess a valid username.


How do I find a "Bitcoin address" for buying Bitcoin?

Question: I am very new to Bitcoin and just learning my way around my Bitcoin wallet, etc. Recently, in order to try to find out more about buying Bitcoin, I clicked on "Buy Bitcoin" in my wallet, but was immediately required to "enter Bitcoin address" before I could go any further.  I don't know what to enter here, or how to find out.  Can someone enlighten me, please ?
Comment: What do you mean by "in my wallet"? Was there some specific web page or program that you were using?
Answer: You have to download a Bitcoin wallet first. I suggest you to download Electrum, it's a lightweight wallet with easy UI. It will generate an address for you.
Answer: You can generate your bitcoin address via here: http://www.bitaddress.org -- make sure you write down or print out your generated private key. You enter your public key into your app you mentioned.
Comment: This is terrible advice.
Comment: @MaxVernon No, BitAddress is completely client side and famous. The reason that it was not a good advice was that, that website only generates an address, and doesn't have a wallet that you can use to make a transaction, see your balance, etc.. The main point here is "If someone asks 'How to generate an address', we should also mention that generating an address is not enough make transactions, a wallet is also needed"
Comment: @MCCCS - perhaps you could improve the answer by adding that the OP would need to have a wallet setup with the keys generated by bitaddress prior to sending transactions to it to avoid losing their money.  I'd guess it might also be important to add guidance making sure they use bitaddress completely offline.


In what way does Spectre have "weak" liveness?

Question: In his article The Spectre Protocol, Aviv Zohar, one of Spectre's authors, mentions that Spectre has weak liveness.
Why does he mention that Spectre has "weak" liveness, and how would "strong liveness" differ from that?
Comment: @KappaDev I think research about better consensus algorithms is very relevant, even if not applicable in the short term. And even if not, this is just a question about the definition of terminology in consensus systems in general.
Answer: The paper explains this:

The  "weakness"  of  the  Liveness  property  corresponds  to  the
  fact  that  we  do  not  guarantee (though  it  is  still  hard  for
  an  attacker  to  prevent)  a  resolution  in  case  conflicting
  transactions were published soon one after the other. Contrast this to
  traditional consensus protocols, where all conflicts are required to be
  decided in finite time, a property usually referred to as
  Liveness. Observe, however, that an honest user of the system will
  never publish conflicting transactions,and will transfer money only
  after he robustly accepted the original funds (the inputs)
  himself; payments of honest users are thus guaranteed to meet the
  conditions formalized in Weak Liveness, and  to  be  robustly
  accepted.  On  the  other  hand,  an  attacker  trying  to  defraud
  must  keep  his attack secret before publishing the conflict, until the
  victim robustly accepts; but then the victim is  guaranteed  that
  w.h.p.  his  transaction  will  not  be  reversed.  Therefore,  these
  two  properties together  ensure  that  payments  of  honest  users
  will  be  robustly  accepted  in  constant  expected time, and that
  they remain robustly accepted forever, w.h.p.


Why did the republic dislike the Jedi in Revenge of the Sith

Question: In Revenge of the Sith Palpatine says he wants all the Jedi to be killed in his speech and the Republic cheers.  What I am wondering is what made them turn on the Jedi?  Didn't they know the Jedi were protecting them?  They must have seen some value in them if they were giving them missions still.  What made them loose trust in the Jedi all of a sudden?
Comment: Well, I don't know the answer but I think you could refer to this http://thefederalist.com/2015/10/22/9-reasons-the-jedi-are-actually-the-bad-guys-in-star-wars/
Answer: They were under the influence of the Sith
A quote from Star Wars: Attack of the Clones, during Obi-Wan's capture by Count Dooku:

Dooku: The truth. What if I told you that the Republic is now under the control of the Dark Lords of the Sith?
Obi-Wan: No, that's not possible! The Jedi would be aware it!
Dooku: The Dark Side of the Force has clouded their vision, my friend. Hundreds of senators are now under the influence of a Sith Lord called Darth Sidious.

So they were already under Sith influence, via Palpatine's skilled words manipulation at the least (and at every step insisting they give him their complete trust and more power), and probably some degree of force power clouding their better judgement. Add this to Palpatine setting the Jedi up to look like they attempted an assassination, and it was an easy thing for the Senate to buy. Why doubt the poor weak Supreme Chancellor, over those war-mongering Jedi who probably secretly became corrupt and wanted to take over?
Comment: +1. Also, the Jedi are a secretive order with powers of mind control; and with one or two exceptions, they come across as smug, arrogant and complacent. They were valued for their services, but I doubt they were generally trusted or loved. Over the years Sidious might have found it quite easy to turn Senators against the Jedi, even without using his Force powers.
Comment: @rc.29 "...and probably some degree of force power clouding their better judgement." <- That was given as a minor potential addition to the "skilled words and manipulation" aspect. What part of that at all implies "sith are gods"? =/ Regardless of by what means, it's canon from the quote I provides (which is proven true by the plot) that they are under his influence, force or no force.
Comment: @Mwr247 Poor answer, basically comes down to "Sith are gods" theory. Palpatine is so powerful he mind controls majority of Senate and public. He does that 24/7 across galaxy, few people are able to think independently. Well, I don't think so. Palpatine is powerful, but is not that powerful .
Comment: @Mwr247 Your answer is basically "Senators were mostly good and honest people but Palpatine managed to trick them" . That implies Palpatine had god like powers, or Senators were incredibly stupid and not suited for job. And if you chose second option, you would need to ask yourself why would there be so many stupid beings in Galaxy's highest chamber ? Is something wrong with Republic in first place ? ;)
Comment: @rs.29 My answer stated nothing about the moral character or mental capabilities of the senators. Palpatine fooled the Jedi as well, through a combination of skilled words and manipulation, as well as some degree of force powers clouding their judgement, and all without them needing to be "weak minded". The summary of the question was "Why did the republic like the Jedi, then change their mind after a simple speech from Palpatine?", which is what I address. Your answer speculates deeper, but there was no significant movement of the Senate wanting to remove the Jedi prior to Palpatine's speech.
Comment: @Mwr247 Palpatine fooled most of Senators and they remained fooled for years. So, either he had divine powers, or Senators were not that bright to begin with. Why is this so hard to understand ? :D Would you want your representatives to be fooled by skilled manipulator ? Or would you want wiser people to represent you ? ;)
Answer: Palpatine told them the Jedi planned to overthrow the Senate
The reason they cheer and applaud Palpatine's plans to seek out and destroy the Jedi was because he had led them to believe the Jedi were planning to overthrow the Senate. Palpatine used his prior confrontation with Mace Windu as evidence that the Jedi attempted to assassinate him - fairly convincing evidence, I'd assume, given his disfigured face.
The gullible Senate fell for it hook, line, and sinker.

The Chancellor is in the podium in the center of the vast arena giving a speech. MAS AMEDDA stands to the right of SIDIOUS. BAIL ORGANA walks through the hallway of the Main Senate Chamber. He enters the Senate Pod of Naboo and sits next to PADME. JAR JAR, CAPTAIN TYPHO and TWO HANDMAIDENS are in the pod also.
PALPATINE: . . . and the Jedi Rebellion has been foiled.
BAIL ORGANA: I was held up. What's happening?
PADME: The Chancellor has been elaborating on a plot by the Jedi, to overthrow the Senate.
BAIL ORGANA: That's not true!
PADME: He's been presenting evidence all afternoon.
BAIL ORGANA: And the Senate will go along with it, just like they always do.
PALPATINE: The remaining Jedi will be hunted down and defeated. (applause) Any collaborators will suffer the same fate.
(applause)
These have been trying times, but we have passed the test.
...
PALPATINE: The attempt on my life has left me scarred and deformed, but I assure you my resolve has never been stronger.
Applause.
Revenge of the Sith Script
Comment: "gullible Senate" :D :D Care to explain how did it come to pass, that Senate, supposedly full of wisest people from across Galaxy, turns out to be chamber of easily fooled bumbling fools ? Could it be that there is something deeply rotten in Republic if something like this happens.
Comment: @rs.29 - I blame the naiveness of the Senate and Palpatine's above average ability to deceive. People love love to blame a corrupt Senate for the fall of the Republic but it just isn't so. A certain amount of curruption existed, sure, but it was the best government the galaxy far, far away had ever known. See the top answer to this question: https://scifi.stackexchange.com/questions/129640/why-did-the-jedi-serve-a-corrupt-republic/129684#129684
Comment: Naive  = stupid. How would supposedly good (best) political system allow so many naive and stupid beings in its highest legislative body ? Solution is simple - Republic was not good political system, it was not even average. It was horribly decadent, corrupt and inefficient. Sith didn't make it that way, they just seized opportunity. Just like disease attacking already weakened body of drug addict.
Comment: @rs.29 - How could they allow so many naive beings? Easy. The democratic process. Democracy is demonstrably better than any other political system we've ever seen and we still see under-qualified representatives elected all the time. It's reasonable to expect that in the GFFA as well. I have a hard time calling the Republic "deeply rotten" as you do when it's clear that they were deceived and that they were only trying to ensure the safety of their constituents.
Comment: @rs.29 - To imply deep seeded corruption is to imply that the Senators acted the way they did for personal gain and not for the gain of those that elected them. They made the wrong decision in granting Palpatine emergency powers and celebrating the conversion to an Empire but I've never seen a shred of evidence suggesting that those decisions were made with anything other than the best of intentions. Until a canon piece is written changing that, the "deep rooted corruption" narrative is nothing more than poor speculation.
Comment: Some senators&representatives were corrupt (Trade Federation), some were stupid (Jar Jar Binks), some were inexperienced (Padme Amidala). In a good system, neither of them would be nowhere near Senate. The fact that so many people "unsuited for job" were elected to make most important decisions is a enough of the proof that Republic as a political system was dying.
Comment: Btw, according to Plato, democracy is second worst system, that ultimately leads to tyranny . I bet Lucas took some ideas :D https://en.wikipedia.org/wiki/Plato%27s_five_regimes
Comment: Good grief... All I have to say on the matter is that there is a reason aristocracies don't exist anymore and almost all of the developed world is run by democracy in some form or another. There's no indication Lucas supported anything else. Especially considering that his story group wrote the New Republic as a very similar government to the prior Republic after the fall of the Empire.
Comment: Cynic in me would say that democracies in Western world are signs of slow but inevitable doom and decadency :D Anyway, in SW universe democracy was corrupt, it was destroyed and never fully restored. Remember, New Republic was short lived, First Order effectively destroyed it when they blew up Hosnian Prime along with Chancellor and most of Senators.
Answer:     Jedi were defenders of corrupt Republic for too long
   At the beginning of Phantom Menace, Republic is horribly inefficient and decadent beast. Senate cannot even decide is one of the member planets invaded ! Not to mention representatives from large corporations in legislature, teenage Senators, bureaucracy etc... And outside of Senate, extreme wealth of monarchs on on side (Alderaan) and extreme poverty on other side, especially in Outer Rim. All of this could not be attributed to workings of couple of Sith Lords, simply saying roots of disaster were inside very core of supposed democracy.
    What about Jedi ? Jedi are secretive Force sect, rumored to "voluntarily" take children from their families, with supernatural powers. Yet, they act like ultimate police force and enforces of Republic, with little control by the public. Or simply, they are the fist of current regime.
  Clone War starts, Jedi suddenly become generals of massive Clone Army. Note that other citizens of Republic mostly do not participate in war, they are unarmed victims and thoroughly depend on others to protect them. There were exceptions, but what most of the people see is Jedi and clones on "our" side, and former Jedi and droids on "their" side. Because, Dooku is a well-known former Jedi, and probably many wondered is he really "former".
    Role of Palpatine. While we know that he is a Sith Lord, general public would see him in a positive light. He was less corrupt then other politicians, remained humble, and was practically only "ordinary" being controlling vast army of Force-sensitives and clones. Basically, he was someone general public could relate to. Jedi try to overthrow him, details are unknown but is certainly illegal. They fail and are removed, and suddenly Clone War with all devastation stops.
  No Jedi no problem ? It certainly looks that way. One of Jedi is leader of CIS, other Jedi attempt a coup, all of them gone and war is gone. Was war just a plot by Jedi to take over ? It looks plausible. Anyway, Palpatine controls Senate, declares Empire, general public is happy to see Old Republic gone and buried, along with Jedi Order that was symbiotically attached to it.


Sump Pump float above or below the French Drain level

Question: I recently bought a house that has a French drain that drains into my sump pump.  We have had a lot of water this year and my sump pump pumps out the water every 2 minutes.  My float is set below the French drain level so the pit never gets over half full.  Is it correct to have the float level be set below the French Drain?
Comment: Welcome to DIYSE. Please [take the tour](https://diy.stackexchange.com/tour) so you know what's expected of you when you ask a question.
Answer: Doesn't sound like a French drain (which typically describes gravity-driven drains that daylight away from the foundation) so much as a conventional drain tile loop connected to your sump  pail.
Most sump pump floats only let the water get halfway up the pail's height or so. I wouldn't want it getting much fuller than that, personally. If you let the water level get above the drain inlet, the entire drain loop is now full of water. You have essentially no margin for error before your basement floods.
I've had cases where my float stuck and the water level got very close to the top of the slab. Because so much water is now present throughout the drain system, the pump has to run for 10 minutes or more to catch up. That's an uncomfortable situation to be in.
Comment: I agree that it would not be a good idea to raise the pump level above the inlet. Keeping the line pumped out helps keep the water level at the foundation low and will help keep the walls dry.+
Answer: If you raise the level so it's running every four minutes rather than every two minutes,  the pump will probably last longer - you'd cut the starts in half, and fewer starts is a good thing.
If it's running that much, I would consider beefing up the system so that if / when that pump fails, the basement doesn't flood.  If it's running that much, it wouldn't have to be offline long before you'd have a mess.
I'd install a second pump with a lead/lag pump controller for redundancy, and an alarm that alerts if the level rises more than an inch or so above the start float level.  You can use home automation products so you get a smartphone alert even if you're away from home when the pumps go down.


When receiving a call, how do you mute the phone?

Question: This might seem like a stupid question, but I couldn't find the answer on this SE so here goes. When I receive a call and my phone starts to ring, how do I mute the phone without answering or dismissing the call? Is this done differently depending on the Android OS version?
Answer: Just press any volume button while its ringing.
On side note, make sure there isnt an option like answer by volume buttons in settings->accessibility. If there is, make sure its disabled. If its not there, then you are fine ;)
Hope this helps.
Comment: Yes this seems to work well. I tested it by having a friend call me (I am using Lollipop) and pressed either volume up or volume down to mute the incoming call without dismissing or answering the call. Also I noticed that simply pressing the power button will do the same muting, same way as with iPhones. Seems to work also when the screen is locked.
Comment: Glad  your query is solved, good luck :-)


Notice more Geomatics questions than GIS specific.

Question: Should this site concern more geomatics questions?  The only problem with geomatics, is no one knows what geomatics is, but everyone knows GIS?
Answer: I only talk about geomatics with canadians, but even then it's hit or miss if they've heard of the word. To tell you the truth, I've been working for companies and agencies with "geomatics" in their name for almost twenty years, and it's in my job title, but I still can't give a definition without mental scrabbling. :)
Comment: Exactly.  People ask me what my education is, and I say Geomatics.  They go: what's that?  I say.  "Geo": Earth, "matics": like mathematics; the art and science of Measuring the earth.  It doesn't work.  We should go back saying surveying, but then that gets confused with Census Surveys.
Answer: Perhaps this is something that should go in the FAQ?

This site is for answering questions related to all things GIS, Geomatics, remote sensing, &c.
Answer: I think part of the reason for this is the large number of stackoverflow users (read programmers) involved in the beta.  Once the site is established and we see more non-programmer GIS types get involved I would expect this to change.
Comment: I would consider myself one of the few GIS folks who are not programmers. I'm a civil engineer and although, I'm not bad with python, I found there is a lot more programming related questions on GIS.se than what I see my GIS folks at the office do. Needless to say. I'm surprised we haven't seen any true surveying questions pop up


Blew my arduino pro mini s4 named component

Question: While working on my project I supplied 12v to my pro mini through raw input and then a s4 named component smoked and my pro mini  stopped working . It didn't turn on either through vcc or raw. The voltage regulator seems completely fine. Can I repair my pro mini. Please help.
Comment: S4 is most likely a Schottky diode. You could try replacing it (in the correct orientation) and hope nothing else is damaged. Don't run it at 12V in the future I guess. The fact that it doesn't start up with just Vcc is not a good sign but you might have to remove S4 from the board first. Do you have a data sheet or schematic  of your particular Pro Mini clone? Is it a 3.3V or 5V version?
Comment: Sorry but i can only tell you that it's a 5 v version.
Comment: How do you konw if the voltage regulator is completely fine? Is that purely based on visual inspection or have you tested it? Since the failure, is it regulating the voltage to 5V (measured with a multi-meter)?
Answer: Many Arduinos have a Schottky diode between the power connector and the voltage regulator as a protection against accidental reverse polarity connection. The official Pro Mini, or the Sparkfun variant, does not.
So you can either de-solder the diode or break it off the board using diagonal cutters and then replace it with either a similar diode -- or with a solder-bridge if you are confident about never connecting power the wrong way around.
It's possible (likely even) that other components that look OK visually are actually damaged. Especially if you can't power the board by connecting a regulated 5V supply to the VCC pin.
Answer: Once you have removed the diode as described in @RedGrittyBrick's answer, you will need to replace it with another. Note you don't have to replace it with a SMD version if you can't get your hands on one. Most electronics shops sell a 1N4004 or 1N4007 diode which would be a suitable replacement.
If worst comes to worst, you could solder a blob of solder across the diode's pads - which would mean you lose the reverse polarit protection - but it would provide a path for your voltage input to go into the regulator.
Comment: The defective component is a Schottky diode. 4001 or 4007 are not Schottky diodes and have much higher Vf. A better replacement would be 1N5817 or an SMD equivalent.
Comment: It doesn't matter in this instance as it is just for reverse polarity. A normal diode is fine, a Schottky diode would be better if you can get one.


Possible missing war table ops after completion?

Question: Has anyone ever noticed if the Choose Successor in Lydes I & II, Investigate Hunter Fell, or any other completed war table operations have disappeared from their war table. I do not remember if I did these, but I am about to finish Demands of the Qun and want to complete these first (if I haven't already).
Answer: The two quests you mention are "provided" by the Ben-Hasserath. They will or will not disappear after Demands of the Qun, depending on the choices you make during that quest. Specifically, they will disappear if:

 you choose to save the Chargers rather than the Qunari dreadnought.

If you have not yet gone to the Storm Coast to start Demands of the Qun, they should be available.


Can the Rpi 3 handle 4 cameras at the same time?

Question: I want to take 4 pictures simultaneously with 4 different cameras on the Raspberry Pi. I have found  this multicamera adapter, but I do not know whether the Rpi can handle taking 4 pictures at the very same time?
Answer: No, not with this multicamera adapter, and not at all.
That adapter is a multiplexer. So at any given time you can pick on of four cameras and take a picture. You can switch to the next camera afterwards and take a picture and then switch to the next... you get the point. I am not sure about the speed but if all cameras stay online, it should not take too long. Like grabbing 1 garbage frame and then a complete frame. If the cameras don't stay online, then it will take approximately 5 frames to adjust brightnes and such each time you switch.
You might want to consider USB Webcams for that. Those are actually more expensive and offer a lower resolution if you try to come somewhere near the official RPi Cam, but definitively can run simultaneously. I had a setup of 3 very cheap 640x480 webcams running well.
Comment: I agree with this answer but what he is saying could be stated differently.  It can be done and you could keep the last frame up on the screen so you could have 4 images up at any given time but you would have a REALLY slow frame rate and they technically would not be streams.  You could conceivably create a screen that gives the appearance of 4 simultaneous images but they would not be.  the product description also has a disclaimer which basically says it may not work... buyer beware.
Answer: This is not really the answer you are looking for but the Compute Modules do have native dual RPi camera support.  However one of the connectors has a full four data channel path and the other only two, but I guess the RPi cameras only use a pair {that does lead to a little bit of speculation as to whether that four channel one could be split so that two cameras could be run on that port for a total of three cameras overall, but I do not have any evidence to support that.}
The Foundation site has this page "Attaching a Raspberry Pi Camera Module to the Compute Module IO Board", which might give further insight...


What ate my cabbage?

Question: I'd like to know what might have eaten my cabbage and what can I do to prevent it in the future?
This is how it looks after it's been devoured:
Comment: It is hard to tell only looking at bite marks. It could be more than only one suspect, think of snails/slugs, caterpillars, or beetles. Try to check if you can see any animals still on the plants to know what is eating it.
Comment: @benn Unfortunately I didn't see any culprits. But I can tell you I have't encountered any snails or caterpillars around.
Answer: Cabbage loopers , green caterpillars , the adults are white butterflys. BT ( bacillus thurengensis) is the main control today. Some time ago I used malathion spray or sevin dust ,but they are politically incorrect today.
Comment: I agree BT (bacillus thurengensis) is a good control. Brassicas are very susceptible to caterpillars and worms. Neem oil with a couple drops of Dawn dish soap in a spray bottle has been effective for me in controlling infestations when I don't have any bacillus thurengensis.

What ate my cabbage?