On Math SE, I saw there were 2 questions from 2 different users which were both repeated about a minute apart from each other, interlaced among each other, as shown below:  In case anybody wishes to check on the details of any of them, the 4 questions in the order shown are , ,  (note: currently deleted), and . It's possible each user just simply tried accidentally posting more than once, but this seems to occur quite rarely from my experience, and for this to happen with 2 users at basically the same time seems quite unlikely. Also, as for 's suggested duplicate of , I believe that most often occurs with the 2 questions posted at basically the same time as each other, but both of the 2 duplicates here were each posted about a minute apart from their earlier one, so I'm not sure if it's the same issue. I checked the list of recent SO questions from around that same time, but didn't see any duplicate questions, exact or otherwise, occurring from the same user, although it's possible any such duplicates were already deleted. Nonetheless, is this something anyone else also saw around that time? Does anybody know if the SE system may have caused these repeats to occur rather than it being due to the users themselves? Note I will check those posts sometime later and, if either user gives feedback as to something they did which may have caused these duplicates, I'll update this post with those details. Update: After about 2 weeks, neither user of the duplicated questions has indicated anything, nobody has reported anything similar happening elsewhere, and there's been no official feedback. Note the 1st &amp; 3rd questions shown above were posted 1 minute &amp; 6 seconds apart, while the 2nd &amp; 4th questions were posted 1 minute &amp; 8 seconds apart. On rereading the suggested duplicate post, I realize a situation described there of initially double-clicking on the Review button and then shortly afterwards clicking on it again may cause the question to be posted twice, with each one being about a minute apart. As such, I am now fairly certain this is just the same issue, with these 2 sets of duplicates occurring so close together in time being just a coincidence.
I've noticed that with the new question asking form, sometimes, attempting to submit a question will post two identical copies of the same question.  I've  (), but at the time, I assumed it was just a temporary fluke. As far as I remember, I just reviewed the question, saw no errors, and submitted it. (That's all the info I have.)  However, I just saw this happen to someone else, so it can't just be a fluke on my end. , and . The author claims there that they did indeed double click the "Review" button, but their question didn't go through since it didn't have a required tag, but when they tried to submit the question with the required tag, they only clicked it once.  Also, now that I think about it, it could not have been just a temporary client-side issue on both our ends. The system is supposed to  if one tries to post more than one question in 30 seconds. Neither of us got a CAPTCHA. This means that the server accepted the double post, and so it's a server issue.  This has the effect of denying users badges that they would have otherwise qualified for, since a single negatively-received, closed, or deleted question . This means that even if the double post is deleted and the original is upvoted, the user won't qualify for that day since they've made a "bad" question on that day. (While they may be able to later reverse this 60 days later by undeleting and re-deleting their question - questions deleted more than 60 days later aren't considered "deleted" for the check - they often won't be able to, since most of the time, users will have downvoted the double post, which also disqualifies one from the badges.)  Can an employee go through server logs to see what happened in both these cases, and add some safeguards to prevent accidental double submissions of questions? This seems to have come up when the new asking form was deployed.  Update: There was another case just now:  was . As both have the exact same time of submission, this is an instance of this bug, since as I said above, this thing is ordinarily prevented by a CAPTCHA.
Does a photon in vacuum have a rest frame? I don't understand, because if 'don't' is 'do not' then wouldn't the sentence without conjunctions be 'do not you dare' which I'm pretty sure isn't grammatically correct. Like, when we say the term it means something else, certainly not 'do not you dare' anyway. Any ideas on why? I am so glad English is my first language. I haven't seen the question stated precisely in these terms, and this is why I make a new question.  What I am interested in knowing is not the definition of a neural network, but understanding the actual difference with a deep neural network.  For more context: I know what a neural network is and how backpropagation works. I know that a DNN must have multiple hidden layers. However, 10 years ago in class I learned that having several layers or one layer (not counting the input and output layers) was equivalent in terms of the functions a neural network is able to represent (see Cybenko's ), and that having more layers made it more complex to analyse without gain in performance. Obviously, that is not the case anymore.  I suppose, maybe wrongly, that the differences are in terms of training algorithm and properties rather than structure, and therefore I would really appreciate if the answer could underline the reasons that made the move to DNN possible (e.g. mathematical proof or randomly playing with networks?) and desirable (e.g. speed of convergence?) How to pass parameters to an alias? For bash script, I can use "$@" to access arguments. What's the equivalent when I use an alias? Why $\sum_{k=0}^m x^k $ is equal to $\dfrac{x^{m+1}-1}{x-1} $? Who can help me proving this (but you can no longer use $\sum$ in the proof):  $$\sum_{k=0}^m x^k=\dfrac{x^{m+1}-1}{x-1}$$ Display number with leading zeros Given: a = 1 b = 10 c = 100  How do I display a leading zero for all numbers with less than two digits? This is the output I'm expecting: 01 10 100 How come if $\ i\ $ not of the following form, then $12i + 5$ must be prime? Show that $F\subset Y$ is closed in $Y$ iff $F=Y\;\cap\;H$ where $H\subset X$ is closed in $X$. I have the following problem:      Let $(X,\tau)$ be a topological space and $(Y,\tau_y)$ be its    subspace, that is $Y\subset X$ and $\tau_y=\{\;A\;\cap\;Y\mid  A\in\tau\;\}$. Let also $F\subset Y$ and $H\subset X$, where $H$ is    closed in $X$. Show that $F=Y\;\cap\;H$ if and only if $F$ is closed   in $Y$.   I solved this problem by assuming that if $F$ is closed then $F=Y\;\cap\;H$, where $H$ is closed in $X$, but I got stuck proving this in the other direction, that is showing that if $F=Y\;\cap\;H$ then $F$ is closed in $Y$.  I tried to do something like this:   Assumption: $F=Y\;\cap\;H$, where $H$ is closed in $X$. If $H$ is closed in $X$ then $X\;\setminus\;H$ is open in $X$ and then $X\;\setminus\;H \in \tau$ which means that $B = (X\;\setminus\;H)\;\cap\;Y\in \tau_y$.  How should I proceed now? Should I investigate the set $B$ now more or what? Is it possible to assign the same value to multiple keys in a dict object at once? Boot partition full, can't remove kernels Wine pollutes "Open With" application list The dialog box in question here is the one you get with the context menu option "open with other applications". Wine seems to have inserted more than a dozen or so entries for each application I install, which makes it a pain to find the correct application:     What can I do to remove the duplicates?     Update: Neither of the two solutions really work. The bug is interesting, but the symptoms does not match my problem (I'm not having problem with uninstalling applications, but rather the things that are inserted after installing them), and with the other one, all references to the Wine application are removed, which actually makes the problem worse (although it may be an acceptable solution if nothing else can be found). So this is still an open question; any takers? Strange object.ray_cast() behavior object.ray_cast() is not behaving as I would expect in Blender 2.77. I understand that it expects object local coordinates, but this problem happens when the object is not translated, rotated, or scaled.  If I edit the shape of the cube mesh without moving the cube, the results of ray_cast() seem plain wrong.  Steps to reproduce   Create a cube at 0,0,0 Move a vertex of the cube from 1,1,1 to 5,5,5 Create an empty called "src" at 2,2,2 Create an empty called "dst" at 2,2,6   Run this python  cb = bpy.data.objects['Cube'] src = bpy.data.objects['src'] dst = bpy.data.objects['dst'] hit, loc, norm, face = cb.ray_cast(src.location, dst.location) bpy.ops.object.empty_add(location = loc)   This is the result on my system. The new Empty created at the interesection point is selected:    The source and the destination are both at x = 2 and y = 2. The cube has a surface at x = 2 and y = 2. So why on earth is the intersection point at x = 2.22222, y = 2.22222? How to update Android Studio in Ubuntu? I am trying to update from version 2.0.0 to version 2.1.2 in Ubuntu 64bit/14.04LTS but when I click "update and restart" it says "Downloading patches" and it closes.   It does not start again and if I try to open it, the version is still 2.0.0.   Is there any tutorial to manually update android studio? (keep all settings and etc). Is there any way to make a custom page.html.twig template in Drupal 8?  By default, Drupal generates some suggestions, but I'm looking for something like page--node--content-type.html.twig. As in  I'm trying to use apa6e and biblatex-apa together and having problems.  Before I arrived at these problems, over the course of many hours of much reading, I first managed to get BibTeX working as expected in a simple input file (by modifying sample2e.tex). Then I managed to get apa6e working as expected based on the author's example in apa6e.pdf (which uses apacite). But when I try to get apa6e working with biblatex-apa, I end up with problems.  Here's my input file:  \documentclass{apa6e}  \usepackage[american]{babel} \usepackage{csquotes}  % biblatex \usepackage[style=apa]{biblatex} \bibliography{biblatex-apa-test-references}  \title{An Example Document} \shorttitle{Psychology: the end} \author{Silly Name}  \authornote{\dots} \abstract{\dots}  \begin{document}  \maketitle  This is an example input\cite{7.01:2} file.  Comparing it with the output it generates can show you\cite{7.01:3a} how to produce a simple document of your own.  \printbibliography  \end{document}   Attempting to typeset this in TeXShop by running LaTeX, then BiBTeX (which based on console messages, does seem to correctly call biblatex rather than BiBTeX), then LaTeX again, I get the following error message which I am having great difficulty (no doubt due to my lack of experience with TeX and co.) decoding.  (./test6.aux) (/usr/local/texlive/2011/texmf-dist/tex/latex/psnfss/ot1ptm.fd) *geometry* driver: auto-detecting *geometry* detected driver: pdftex (./test6.bbl) Underfull \hbox (badness 10000) in paragraph at lines 18--18  []\OT1/ptm/m/n/12 An Ex-am-ple Doc-u-ment   Underfull \hbox (badness 10000) in paragraph at lines 18--18  []\OT1/ptm/m/n/12 Silly Name   Underfull \hbox (badness 10000) in paragraph at lines 18--18  []\OT1/ptm/m/n/12 Author Note  [1{/usr/local/texlive/2011/texmf-var/fonts/map/pdftex/updmap/pdftex.map}] Underfull \hbox (badness 10000) in paragraph at lines 18--18  []\OT1/ptm/m/n/12 Abstract  [2] Underfull \hbox (badness 10000) in paragraph at lines 18--18  []\OT1/ptm/m/n/12 An Ex-am-ple Doc-u-ment   Underfull \hbox (badness 10000) in paragraph at lines 25--25  []\OT1/ptm/b/n/12 References  ./test6.tex:25: Undefined control sequence. &lt;argument&gt; \mkbibdateapalongextra  (/usr/local/texlive/2011/texmf-dist/tex/latex/psnfss/ot1pcr.fd) (/usr/local/texlive/2011/texmf-dist/tex/latex/psnfss/ot1ztmcm.fd) (/usr/local/texlive/2011/texmf-dist/tex/latex/psnfss/omlztmcm.fd) (/usr/local/texlive/2011/texmf-dist/tex/latex/psnfss/omsztmcm.fd) (/usr/local/texlive/2011/texmf-dist/tex/latex/psnfss/omxztmcm.fd) Overfull \hbox (8.03372pt too wide) in paragraph at lines 25--25 [][]  \OT1/ptm/m/n/12 Gilbert, D. G., Mc-Cler-non, J. F., Ra-bi-novich, N. E.,  Sugai, C., Plath, L. C., As-gaard, G., ... Botros,  ./test6.tex:25: Undefined control sequence. &lt;argument&gt; \mkbibdateapalongextra                                    {year}{month}{day}\iffieldundef {endyear}{... l.25   I tried many different sources in several different *.bib files before eventually trying the .bib database shown above and included with biblatex-apa. All trials gave a similar error.  Can someone help? I'm impressed that the poster above was able to do anything with apa6e and biblatex-apa, and if I only had her problem of having the reference page title show up in bold, I'd be really happy.  If you need to know, my tools are from a fresh installation of MacTeX that I immediately updated using the TeX Live Utility. I've checked my versions for apa6e (v0.3) and biblatex-apa (v4.2), and I think these are current. Estimator for $\theta$ using the method of moments Exercise :     Using the method of moments, find the estimator for $\theta$ for a random sample $X_1, \dots, X_n$ that follows the distribution with pdf $f(x) = \theta x^{-2}, \; 0 &lt; \theta \leq x &lt; \infty$, where $\theta$ is the unknown parameter.   Attempt :  $$m_1' = \bar{X}$$  $$μ_1' = \int_\theta^xu\theta u^{-2}\mathrm{d}u=\int_\theta^x\theta u^{-1}\mathrm{d}u=\big[\theta \ln u\big]_\theta^x =\theta\ln x - \theta\ln\theta$$  Thus, the estimator is given by :  $$m_1' = μ_1' \Rightarrow \theta\ln x - \theta\ln\theta = \bar{X}$$  But we cannot solve that equation with respect to $\theta$, so we'll take the moments of bigger order :  $$m_2' = \frac{1}{n}\sum_{i=1}^nX_i^2$$ $$μ_2' = \int_\theta^x u^2 \theta u^{-2} \mathrm{d}u = \int_\theta^x \theta \mathrm{d}u = \big[\theta u\big]_\theta^x =\theta x - \theta ^2 $$  Thus the solution of the following quadratic equation for $\theta &gt;0$, gives as the estimator of $\theta$ :  $$\theta^2-x\theta +\frac{1}{n}\sum_{i=1}^nX_i^2$$  Question : Is my solution correct ? Shall the upper bound be $x$ or $\infty$ ? Let $A$ be a squared matrix, and suppose there exists an $n\in \Bbb N$ in a way that $A^n=0$. Show that $I-A$ is invertible and that $(I-A)^{-1}=I+A+\cdots+A^{n-1}$    I don't have a clue where to start from. Advanced format partition alignment I cloned a non Advanced Format drive (W7 64bit) to a new hard drive (Seagate) that was AF, the software I used supposedly does not support 4k very well (Todo Backup Free 3.5).   Is there a Windows utility to check alignment? I know of the Western Digital tool but not sure if it works on Seagate brand drives. If the partitions are not aligned, Am I better to clean install W7 64bit or do the partition alignment procedure? If so, Why?   It seems to be running fine so far. From what I have read Seagate drives use  technology to help with misaligned partitions on the fly, might explain why it runs well for me, but would still like to have the partitions aligned properly.  EDIT: Here is the diskpart output for my disk partitions  DISKPART&gt; list partition    Partition ###  Type              Size     Offset   -------------  ----------------  -------  -------   Partition 1    Primary            188 MB    31 KB    Partition 2    Primary            698 GB   188 MB How are House points tabulated/tracked? Repeatedly rolling a six sided die four times and summing the highest three results gives you a distribution with what mean and standard deviation? Repeatedly rolling a six sided die four times and summing the highest three results gives you a distribution with what mean and standard deviation?  I've only taken AP statistics, but I would like to learn how to do this.