I frequently see users across all communities with a display name of "user" followed by a bunch of numbers, or in terms of a regex, user\d+. This doesn't seem like an elaborate username choice, so what's going on?
It's been more than a month since I have started using . It has these users with user names in the format of "user-random number". I have observed them in some of the stack activities, most of the time asking questions.   Does the moderators create them for their own purpose. If yes what purpose do they serve?   I mean a user is free to have any user name. But it's just a hunch that such users are actually moderators. I may be wrong; just need some clarification.
I define a shell keybinding in my ~/.bashrc like so:  bind -x '"\e\C-w":"/usr/bin/reset"'   This does make Ctrl-Alt-w launch the reset executable. However, it leaves the terminal in a state that resembles the one you get into by pressing Ctrl-v. So, for example, if immediately after resetting in this way I press Ctrl-p, instead of invoking the action of that shortcut (repeat previous command) I get ^P printed.  Any idea what's causing this problem and how to fix it?  EDIT: I am attaching a Python program that reproduces the messed-up terminal state I am trying to fix with the reset. I encounter this condition very often while debugging multi-threaded applications:  import pdb, thread, time  def interrupt():     time.sleep(2)     pdb.set_trace()  thread.start_new_thread(interrupt, ()) raw_input('? ')   To reproduce the messed-up state, just run the code above, and press Enter when you see the debugger invoked (it will print a bunch of text, ending with pdb.set_trace(), about two seconds after you run the program and the initial prompt appears). Regular Expression to match valid dates Property of Entire Functions $P$ is a prime ideal of $R$ iff $R/P$ is an integral domain. : $P≠R$ Here is the theorem and proof in my textbook.     Thm.  Let $P$ be an ideal of a commutative ring $R$ with identity $1$.  Then $P$ is a prime ideal of $R$ if and only if $R/P$ is an integral domain.   Proof.   Suppose that $P$ is a prime ideal of a commutative ring $R$ with $1$.  Then $P$≠$R$ implies $1+P≠0+P$. Hence $R/P$ is a commutative ring $R$ with identity.  Assume that $(a+P)(b+P)=0+P$.  Then $ab+P=0+P$ and $ab∈P$.  By the definition of a prime ideal P we get $a∈P$ or $b∈P$.  That is, $a+P=0+P$ or $b+P=0+P$.  Thus $R/P$ is an integral domain.   Conversely, if $R/P$ is an integral domain, then $1+P≠0+P$ and $R/P$ is a commutative ring $R$ which has no zero divisors.  Hence $P≠R$.  Assume $ab∈P$.  Then $ab+P=0+P$ and $(a+P)(b+P)=0+P$.  Since $R/P$ is an integral domain, we get $a+P=0+P$ or $b+P=0+P$.  So $a∈P$ or $b∈P$.  Thus $P$ is a prime ideal.    I am having problems understanding proof with "Conversely, if $R/P$ is an integral domain, then $1+P≠0+P$.".  I know that $R/P$ has an identity. (cause it is ID)  But, why doesn't "$P$" have an identity?  Isn't there a case $P=R$?  Please help me understanding. I think $P≠R$ should be with condition of Thm..  Thank you in advance. Making a (simple) directory tree I'm trying to make a simple directory tree representation in LaTeX. Something like:  spam  |  +-- ham  +-- eggs      |      +-- more spam      +-- dead parrots   The tree won't be that long (say, 10--15 entries or so), with three or so levels, and is a one-off thing. So, quick-and-dirty solutions are welcome. When recommending tikz, please note that I have almost no experience with it, so I'd appreciate a clean simple solution, even if it doesn't look quite perfect.   On Tex.SE tikz is almost like the jquery recurring joke on StackOverflow..    Edit: As per Thorsten's suggestion,  is a nice and easy-to-use solution. The example from above could be written as:  \usepackage{dirtree} ... \dirtree{% .1 spam. .2 ham. .2 eggs. .3 more spam. .3 dead parrots. } How to plot the first n rows of a table using pgfplots? When using pgfplots, is there a way to plot only the first n rows of a given table ?  Considering the following MWE file:  \documentclass[tikz]{standalone}  \usepackage{tikz} \usepackage{pgfplots} \pgfplotsset{compat=newest} \usepackage{amsmath}  \begin{document}      \begin{tikzpicture}         \begin{axis}[%             width=16cm,height=8cm,             view={-45}{65},             scale only axis,             xmin=200,xmax=500,             xlabel={data1},             ymin=0,ymax=100,             ylabel={data2},             zmin=0,zmax=1,             zlabel={data3},         ]         \addplot3 [             thick,smooth,             color= darkgray,             solid]             table[row sep=crcr] {                 250 0 0\\                 250 25 0.2\\                 250 50 0.3\\                 250 75 0.2\\                 250 100 0\\             };          \addplot3 [             thick,smooth,             color= darkgray,             solid]             table[row sep=crcr] {                 450 0 0.5\\                 450 25 0.1\\                 450 50 0\\                 450 75 0.1\\                 450 100 0.5\\             };         \end{axis}     \end{tikzpicture}% \end{document}   How can I plot only the first n=4 rows of each table and ask pgfplots to stop reading the table once this row is reached ?  Of course, for the above example, this seems useless, but when huge data tables are used, this could be extremely usefull, in particular to use the same data and focus on different parts of the table in different figures. Sometimes when I'm making a sauce or soup that needs to be a bit spicy, I have no troubles spicing how I want to.  But if the dinner party is a bit late, or I made the sauce in advance to really draw out all the flavors of the spices, vegetables and meat, sometimes I end up with a way too spicy/hot dish.  You can always pour a bit water and try to dilute it a bit, but that also takes away all of the good flavor. So is there some trick that I'm missing I can use, when this happens to me (other than being more careful or using the spices later)? I would that the images would appeared for each overlay. Eg, in overlay 1 I have img1.pdf, in overlay 2 I have img2.pdf, and in overlay 3 I have img3.pdf. How I do this?  \begin{center}   \begin{tikzpicture}     \node (img1) {\includegraphics[width=.5\linewidth]{img1.pdf}};     \pause     \node (img2) {\includegraphics[width=.5\linewidth]{img2.pdf}};     \pause     \node (img3) {\includegraphics[width=.5\linewidth]{img3.pdf}};   \end{tikzpicture} \end{center} So I noticed that many cards with tap-effects ship with a clause specifying that they can only be used on untapped permanents, such as  and .  So here's my question:   Doesn't that imply that, given the right situation, one can legally tap an already tapped permanent?   I'll give an example of the kinda scenarios this is relevant for: Can  activate her first ability when no untapped cards are around? Or, thinking untap-effects, could I bounce a forest with  even when there isn't a tapped creature available?  Notice that, unlike the previous batch of examples, the wording on these lacks the clause restricting their use to un/tapped permanents - does that mean that they aren't?  Any kind of clarification would be greatly appreciated here. Calculate business days I need a method for adding "business days" in PHP. For example, Friday 12/5 + 3 business days = Wednesday 12/10.  At a minimum I need the code to understand weekends, but ideally it should account for US federal holidays as well. I'm sure I could come up with a solution by brute force if necessary, but I'm hoping there's a more elegant approach out there. Anyone?  Thanks. Add markdown toolbar to mobile web On the full site, there's that helpful Markdown toolbar above the post box:   This is conspicuously missing in the mobile site:   It's difficult just to get a bracket on my iPad. Backticks aren't even available. If there's a view that really needs it, i vote mobile. Opening PDF in Illustrator breaks up text objects I recently had to convert some PDF files to SVG, and did this by opening the PDF in Illustrator, and saving out to SVG.    The issue was that when Illustrator opened the pdf, many (but not all) text objects would be broken up into different text objects.  For instance, the word "policy" wouldn't be one text object, but rather several text objects, "po", "l", "icy".  There didn't seem to be any rhyme or reason to it.    How can I prevent this from happening? Unicode applies the convention of using a  as signature at the beginning of a text stream, identifying the encoding used within it. The following three bytes at the beginning of a file: EF BB BF, identifies this file as a UTF8 file. Vi and most text editors gracefully ignore this signature. Open office does that as well, but it adds this signature at the beginning.  Now, if I open a TeX file with OpenOffic.org, and I do that quite a lot (for mixed directionality editing), the signature is added, and baffles LaTeX, which produces an error message such as:   ! LaTeX Error: Missing \begin{document}.   See the LaTeX manual or LaTeX Companion for explanation.  Type  H &lt;return&gt;  for immediate help.  ...                                                l.1   ��\documentclass{article}   whereas a simple dump of the file does not show the problem. Is there a way to eliminate this problem, while staying in the realm of latex? How does new shield system work? After the upgrade I can't figure out how the new shield system works. I have the option to discard the shield, and I notice I have a new potion in the inventory.  More importantly, I got attacked (and lost) twice in a short amount of time and don't have a shield. When do you now get shield? NIST randomness test p values I have a binary sequence of length $2^{20}$. I am using the NIST statistical test, assess.   What should be taken for ./assess and  How many bitstreams? in this test? In the final Analysis report, what p-values should be there to pass this test? What is the Fastest a Character Can Move in One Turn? At level 20 with any magic items in the DMG, and any spells, what is the fastest a DnD 5e character could move using their movement?  (i.e., not including teleportation) Sample query/DDL for producing page locks on a clustered index in SQL Server (without hints) We currently have some indexes where ALLOW_PAGELOCKS is set to off. This presumably was done in order to reduce deadlocks. However I doubt that it would really had an effect back then.   Now I am trying to understand WHEN SQL Server actually chooses to start locking pages rather than keys in a clustered index. I asked Jonathan Keyhaisas recently and he told me that this could happen if I am touching rows on several subsequent pages. However I didn't manage to get any exclusive page locks by updating rows in a clustered index with a sample query.   Could you help me understand page locks better with a sample query and table? I am running SQL Server 2008 SP4.  Thanks in advance  Martin Check out the below program.   try {     for (String data : Files.readAllLines(Paths.get("D:/sample.txt"))){         String[] de = data.split(";");         System.out.println("Length = " + de.length);     } } catch (IOException e) {     e.printStackTrace(); }   Sample.txt:   1;2;3;4 A;B;; a;b;c;   Output:   Length = 4 Length = 2 Length = 3   Why second and third output is giving 2 and 3 instead of 4. In sample.txt file, condition  for 2nd and 3rd line is should give newline(\n or enter) immediately after giving delimiter for the third field. Can anyone help me how to get length as 4 for 2nd and 3rd line without changing the condition of the sample.txt file and how to print the values of de[2] (throws  ArrayIndexOutOfBoundsException)? I would like to run a script from the main ubuntu shell as a different user that has no password.  I have full sudo privileges, so I tried this:  sudo su -c "Your command right here" -s /bin/sh otheruser   Then I have to enter my password, but I am not sure if that script is now really running under that user.  How can I confirm that the script is really running under that user now? As I prefer outer parentheses to grow larger in nested expressions, I happen to insert \bigl and \bigr and its larger cousins a lot. I have always wondered whether there is a way to do this automagically.  Inserting \left and \right prophylacticly before all opening and closing parentheses and hoping that it sorts things out doesn't do the trick in all cases as seen below.  The left column is without any size changing commands. The middle column as a \left \right pair at every parentheses/brace/bracket and the rightmost column shows my preferred version.    As seen in the middle column of the second and third line the \left and \right pair sometimes makes the outer parentheses larger, on the cost of an extra horizontal space between \Pr and (. The extra space is fine in case of really big opening parentheses but here I'd prefer the regular spacing.  \documentclass{scrartcl} \usepackage{amsmath} \usepackage{amsfonts} \begin{document} \begin{align*} &amp;1-(1-F(x))^n&amp;&amp;1-\left(1-F(x)\right)^n&amp;&amp;1-\bigl(1-F(x)\bigr)^n\\ &amp;\Pr(X_{(1)}\le x)&amp;&amp;\Pr\left(X_{(1)}\le x\right)&amp;&amp;\Pr\bigl(X_{(1)}\le x\bigr)\\ &amp;\mathbb{E}[\min\{X_1,X_2\}]&amp;&amp;\mathbb{E}\left[\min\left\{X_1,X_2\right\}\right]&amp;&amp;\mathbb{E}\bigl[\min\left\{X_1,X_2\right\}\bigr]\\ &amp;\left(\pi-\arccos(\frac{y}{r})\right)&amp;&amp;(\pi-\arccos\left(\frac{y}{r}\right))&amp;&amp;\left(\pi-\arccos \left(\frac{y}{r}\right)\right) \end{align*} \end{document}   As mathematical expressions can be arbitrarly complex there is probably no general way to do this. But I’m not asking for a solution of the general case. A partial solution that works in the simple cases shown above would be a big help. The simple rule could be, that parentheses never shrink below the size of an inner pair. Of course you can immediately think of extensions like a \mid in a conditional expectation that grows with the size of the expectation’s brackets.  What is your preference regarding the size of nested parentheses? Is there a better way to archieve your preferred style despite inserting \bigl \bigr manually?    EDIT:  A colleague pointed me to section 8.3 of Herbert Voß’  document where size problems with parentheses are solved by playing with two TeX parameters within a group around the expression in question. This led naturally to appendix G of the TeXbook where the mechanics of \delimitershortfall and \delimiterfactor are explained.  \delimitershortfall specifies the maximum space not covered by a delimiter (default 5pt) and \delimiterfactor is the ratio for variable delimiters, times 1000 (default 901).  I used them to implement the never shrink below a subformular size idea from above by setting the shortfall to 0pt and the ratio to 1.0.    While it works nicely in line one and three, in line two and four the parentheses now grow too much, and still there is the extra horizontal space introduced by \left.