I discovered this yesterday when i was making a Meta post on Anime and Manga.SE and i just did a test on Stack Overflow.SE's Meta and right here (after remembering i forgot to report it).  In Chrome When you go to "Ask Question" and tick "Answer your own question" then tick "community wiki" you get what i'm quite sure is a Javascript Alert box warning you about how by making a Community Wiki you remove explicit ownership of the answer, bla, bla, bla.  Regardless if you click "Ok" or "Cancel" it appears a second time. don't know if it occurs in any other browser. kinda minor but a bug is a bug and i would think there are some people are twitching uncontrollably because of it.
Click Answer your own question Check community wiki A dialog box     Are you sure you want to make this post Community Wiki?   will appear, Click OK or Cancel; The same dialog will appear again.   Google Chrome 44.0.2403.107 / Windows8.1 / site rev 2015.7.25.3609
Dear Academic SE advisers,  I am a college sophomore in US with double majors in mathematics and microbiology. My algorithmic biology research got me passionate about the number theory and analysis, and I have been pursuing a mathematics major starting on this Spring semester. I have been independently self-studying the number theory textbooks written by Niven/Zuckerman/Montgomery, Apostol, and Ireland/Rosen on this semester. As this semester progressed, I discovered that I am more interested in the pure mathematics than applied aspects (computational biology, cryptography, etc.). I want to pursue a career as analytic number theorist and prove the Collatz conjecture and Erdos-Straus conjecture.   I have been thinking about doing the number-theory research on my university (research university; huge mathematics department). I have been self-studying the NT by myself and also regularly attending the professional and graduate seminars on number theory but I did not do any pure mathematics research as an undergraduate. Should I visit NT professors in my university and ask them about if I can do undergraduate research under them? If research is not possible (perhaps due to my lacking maturity), should I request of doing independent reading under them and later proceed with the research? How should I ask them? What should I address? If even independent reading is not desirable to them, what should I ask to them or do in my own?   As for my mathematical background, I have been taking Calculus II (computational) and discrete mathematics. I will be taking calculus III (vector calc.) on Summer, followed by Analysis I, Probability, Theoretical Linear Algebra on Fall 2015. As for my self-studying on this semester, I have been studying NT textbooks (mentioned above), proof methodologies, and basic linear algebra.   Thank you very much for your time, and I look forward to your advice!  Sincerely,  PK I want to start using the terminal more often, but I don't know what are the different commands available to me. Is there a way to list all the different commands that I can make use of? Is it true that if $A$ is a nonnegative primitive matrix, then $AA^T$ is also primitive? Obviously $A^T$ is primitive but in general product of primitive matrices is not primitive.  Any hint? Determine $4$ specific digits in $34!$ Find the values of $a,b,c,d\in\mathbb{N}$ such that      $$ 34!=295232799cd9604140847618609643ab0000000 $$   My Attempt:  The factorial of $34$ contains a $3$, so the RHS must be divisible by  $3$. Similarly, it must be divisible by $7$, $11$, $13$, $19$ etc.  But I do not understand how can I calculate $a,b,c,d$ in this equation. I have a point $(X,Y)$ on an elliptical curve $E(a,b)$ where $a=-3$ and $B$ is a large number that is in hexadecimal from -51BD. To compress this point oficially in a program, we know that every $X$ on the curve has two $Y$'s, one even and one odd. Therefore, we only need to store whether the corresponding $Y$ point we are storing is even or odd. So to store the point $(X,Y)$ now, we shift $X$ ridding of its most significant bit and add $1$ if the $Y$ point is odd. Therefore, one can think of the compressed point being $2 \cdot X+B$ ($B$ is the bit we added to tell if $Y$ was odd or even) since the multiplication by $2$ is implied because of the shift. I understand this completely. It's recovering the original point that has me confused.  Since a point on the curve is given by the equation $y^2=x^3+ax+b$, we can find square roots officially in $\mathrm{GF}(p)$. The following from my spec is what confuses me.  If $p$ is prime and congruent to $3$ mod $4$, one of its square roots is $z^{(p+1)/4} \bmod p$ and the other is $p-z^{(p+1)/4} \bmod p$. How would I solve this? What is $z$?  For example, I know how to extract the $x$ point so let's say I simplify the right side of the equation to be $7$ and $p$ is $11$. Would I be trying to solve for the square root that's equal to $7$ mod $11$? better Curve/Text to Mesh generation? The triangulation process of Text to Mesh or Curve to Mesh generates some nasty topology.   I get why, but maybe it could be done a bit nicer? Since text is flat, have ngons instead of hundreds of triangles you'll need to modify anyway?  Another issue is when you then want to use the text as a Volume for particles, which for some reason behave weird when you have unusual topology even though they should be using the volume, not vertex or face positions. "The pair was ..." or "the pair were ..." I was talking to a friend who owns a Mac. He has his set up so that when he swipes three fingers across his touchpad, it moves to the workspace in that direction. Is it possible to set this up in Ubuntu? Which textbook is good for introductory group theory? How to list files in a zip without extra information in command line In my bash command line, when I use unzip -l test.zip I get the output like this:  Archive:  test.zip   Length      Date    Time    Name ---------  ---------- -----   ----    810000  05-07-2014 15:09   file1.txt    810000  05-07-2014 15:09   file2.txt    810000  05-07-2014 15:09   file3.txt ---------                     -------   2430000                     3 files   But I am interested only by the lines containing the file details.  I tried to make filtering using grep like this:   unzip -l test.zip | grep -v Length | grep -v "\-\-\-\-" | g -v Archive | grep -v " files"  But it is long and prone to error (e.g a file name Archive in this list will be dropped)  Is there any other options with unzip -l (I checked the unzip man page and did not find any) or another tool to do so?  It is important to me to not really unzip the archive but just to look what files are inside. I understand that faster-than-light communication is impossible when making single measurements, because the outcome of each measurement is random. However, shouldn't measurement on one side collapse the wave function on the other side, such that interference effects would disappear? Making measurements on "bunches" of entangled particles would thus allow FTL communication, by making observed interference effects appear or disappear. How does such an experiment not:  1) Clearly imply that faster-than-light communication is possible?  or  2) (if #1 is rejected) Imply that measurement of one half of an entangled pair does not cause the collapse of the other half's wave function.  Why doesn't this thought experiment clearly show that if we maintain that FTL communication is ruled out, we must also rule out "universal collapse" in the Copenhagen interpretation?  EDIT: Here is an example of an explicit experiment (though I think experts could come up with something better):  You can entangle a photon with an electron such that the angle of the photon is correlated with the electron's position at each slit of a double slit experiment. If the photon is detected (it's outgoing angle measured), then which-path information is known, and there is no interference. If the photon is not detected, the interference remains.   The experiment is designed such that the photon and electron go in roughly opposite directions, apart from the tiny deflection which gives which-path information. You set up a series of photon detectors 100 ly away on one side, and your double slit experiment 100 ly away in the opposite direction. Now you produce the entangled pairs in bunches, say of 100 entangled pairs, each coming every millisecond, with a muon coming between each bunch to serve as a separator.   Then the idea is that someone at the photon detector side can send information to someone watching the double-slit experiment, by selectively detecting all of the photons in some bunches, but not in others. If all of the photons are detected for one bunch, then the corresponding electron bunch 200 ly away should show no interference effects. If all of the photons are not detected for one bunch, then the corresponding electron bunch 200 ly away would show the usual double-slit interference effects (say on a phosphorus screen). (Note that this does not require combining information from the photon-detector-side with the electron-double-slit side in order to get the interference effects. The interference effects would visibly show up as the electron blips populate the phosphorus screen, as is usual in a double-slit experiment when which-path information is not measured.)  In such a way the person at the photon detectors can send '1's and '0's depending on whether they measure the photons in a given bunch. Suppose they send 'SOS' in Morse code. This requires 9 bunches, and so this will take 900 milliseconds, which is less than 200 years. The point is that such an experiment would only work if you assume that the measurement of the photon really does collapse the wave function nonlocally. How to assign from a function which returns more than one value? Why does an argument similiar to 0.999...=1 show 999...=-1? I accept that two numbers can have the same supremum depending on how you generate a decimal representation. So $2.4999\ldots = 2.5$ etc. Can anyone point me to resources that would explain what the below argument that shows $999\ldots = -1$ is about? Here is the most usual proof I see that $0.999\ldots = 1$:  $x=0.999\ldots$ $10x=9.999\ldots$ $10x - x = 9$ $x=1$  Using this same argument template I can show $999\ldots=-1$:  $x= \ldots9999.0 $ $0.1x= \ldots9999.9$ $0.1x - x = 0.9$ $x=-1$  What might this mean? Edit from one of the comments: $$\sum_{k=0}^{\infty}{9 \cdot 10^k}=-1$$ I'm not sure if this is the right place to ask this question. I realise that this maybe a borderline philosophical question at this point in time, therefore feel free to close this question if you think that this is a duplicate or inappropriate for this forum. Anyway, I'm an electrical engineer and I have some basic knowledge of quantum mechanics. I know that Schrödinger's equation is deterministic. However, quantum mechanics is much deeper than that and I would like to learn more. If this question is not clearly answerable at this point than can anyone point out some recognized sources that try to answer this question. I would appreciate it if the source is scientific and more specifically, is related to quantum theory. In the android app, looking at bounty details using the i button, the bounty reasons are not shown:        The bounty message can provide important information as to the setter's requirements (who may not be the OP and therefore does not wish to edit the question to do so). Assigning strings to arrays of characters I am a little surprised by the following.  Example 1:  char s[100] = "abcd"; // declare and initialize - WORKS   Example 2:  char s[100]; // declare s = "hello"; // initalize - DOESN'T WORK ('lvalue required' error)   I'm wondering why the second approach doesn't work. It seems natural that it should (it works with other data types)? Could someone explain me the logic behind this? cp -r is meant to copy files recursively, and cp -R for copying directories recursively. But I've checked, and both appear to copy both files and directories, the same thing. So, what's the difference actually? I am trying to find the correct opposite of a delegate in the context of a person being a representative of someone else that have allowed or chosen them to be their delegate. What would you call that "someone else?" The only word I could find is a delegator (which isn't a real word in English) or assigner, but they are technical words rather than descriptive.    Any other word I could use?    Think of it in a sentence like this:       Here is a list of all the delegates in the company.   But that is the list of their _ _ _ _ _ (what can go here?).   I am trying to avoid fillers such as:  bosses, agents, managers, etc. I see that there a number of questions (, , , , ) on best practices, none of them answer the issue I am going to talk about.  We all need to prepare large documents (or slides) from time-to-time. And once you have reached a certain number of pages, you find that compiling the whole document takes a substantial time, which you need to do to check that the part you have written is error free, specially if it contains a number of images.   To circumvent the situation, I have used the following practices over years to keep compile time at minimum.   Divide the document in to many chapters: The chapters are put in separate files. Only the one I am working one is uncommented.  \documentclass{book}  \begin{document}  %\input {chapterone.tex} \input {chaptertwo.tex} %\input {chapterthree.tex} %\input {chapterfour.tex}  \end{document}    The above technique can also be used for \include.   Keep a preamble replica of the main file in a temporary file (build file): I use this technique when I am preparing a presentation with many slides, say a hundred. Prepare a main file, copy it to another build file. Delete everything between  \begin{document} and \end{document} in the build file. Prepare a slide (or a group of slides) in the build file. Cut and paste the contents between \begin{document} and \end{document} in the build file to relevant location in the main file only when satisfied with the output (image locations, overfull boxes etc.)     We can hear your inputs about the best practices you practice when a you are preparing a document or presentation from scratch.    Now, I have failed to find a good answer in the case when you have finished the whole document or presentation and now you need tweaking the small things, may be edit a text here, add an image there. What will be your best practice?  Perhaps, again keeping only one chapter uncommented will be usable here. But what about large presentations? May be adding a \end{document} just after the point-of-change will be beneficial, but only if you can put that before midpoint of the file.  Commenting a part of the file will also work, but that is error-prone, at least for me. If I perform RSA on my input 5 times, I get the original input back out. Why is it that often, iterating RSA encryption just a few times cycles yields back the original value, when the public modulus N is small?