I ran into an issue earlier today where I tried to comment on someone's post to indicate they should make sure they used an @2x and @3x image (iOS stackoverflow question). I was then shown a dialog saying I could only reference / reply to one user at a time. I had to delete one of the @ symbols to be able to post my comment. There were no users I could reference named 2x or 3x, so why was I shown this message? Although a small one, is this a known issue?
Possible Duplicate:             I faced this issue today when I was replying to a comment posted which used @Transaction annotation.     @Trevor: @Transaction and ... @Transaction   When typing this comment, I got a warning.
Is Stack Exchange / Stack Overflow available for private or internal use? Is the Stack Exchange engine that powers Stack Overflow available to download or install internally for an enterprise or company?  I think Stack Exchange's engine is very great and could be very cool to use for internal enterprise patterns and practices, like the engine of Wikipedia. I am sure there is something wrong i am doing but i just want someone to point it to me.  Why can't we say that $e^{\frac {\pi i}{3}} = \left(e^{\pi i}\right)^{\frac {1}{3}} = (-1)^{\frac {1}{3}} = -1$ Why do we have to calculate it by the formula as it is (which produces different value)  Another question is why can't we say that $ (-1)^{\frac {1}{2}} = \left(\left (-1\right)^{2}\right)^{\frac {1}{4}} = 1^{\frac {1}{4}} = 1$  Again i have to say that i know this is all wrong i just want to know why it is wrong Will having multiple domains improve my seo? How do I rename all folders and files to lowercase on Linux? Who in the DC Universe can stop Superman if he has a breakdown? Is there anything or anyone in the DC universe that can defeat Superman just in case he goes berserk on everybody?  Maybe Batman stores kryptonite in his Cave or something. I don't know if Batman actually has kyptonite, the example was just a theoretical example.  Who can stop Superman if needed, and how? What does 1x1 convolution mean in a neural network? I am currently doing the Udacity Deep Learning Tutorial. In Lesson 3, they talk about a 1x1 convolution. This 1x1 convolution is used in Google Inception Module. I'm having trouble understanding what is a 1x1 convolution.  I have also seen  by Yann Lecun.  Could someone kindly explain this to me? How do you pull first 100 characters of a string in PHP I am looking for a way to pull the first 100 characters from a string variable to put in another variable for printing.    Is there a function that can do this easily?  For example:  $string1 = "I am looking for a way to pull the first 100 characters from a string variable to put in another variable for printing."; $string2 = 100charfunction($string1); print $string2   To get:  I am looking for a way to pull the first 100 characters from a string vari How can I disable Ctrl+Q for all applications (system wide)? A lot of applications like Firefox, Chrome etc, get closed when I accidentally press Ctrl+Q instead of Ctrl+W because of the proximity of the Q and W keys on the keyboard. Is there a way this shortcut can be removed or reset on a system wide basis? Why are "south" and "southern" pronounced with different vowels? I was wondering why we pronounce the vowels in the words south and southern. They seem to be very closely related to each other. Both refer to the same direction. South is a noun and Southern is an adjective, which I don't think caused them to have a different vowel. Oxford Dictionary shows that south is /saʊθ/ and southern is /ˈsʌð(ə)n/. In short, south has a long vowel and southern has short. Can I force WordPress to use  instead of ? Flowchart using Tikz I'm trying to create a fine flowchart that is a bit complicated. Therefore I need a block for a predefined process and a connector block as well as a data block. Can someone help me? In comment is what I'd like to see in my code to keep my code nicely arranged. The rest of the code is a simple example for the Tikz site.  \documentclass{article}  \usepackage[latin1]{inputenc} \usepackage{tikz} \usetikzlibrary{shapes,arrows} \begin{document} \pagestyle{empty}   % Define block styles \tikzstyle{decision} = [diamond, draw, fill=blue!20,      text width=4.5em, text badly centered, node distance=3cm, inner sep=0pt] \tikzstyle{block} = [rectangle, draw, fill=blue!20,      text width=5em, text centered, rounded corners, minimum height=4em] \tikzstyle{line} = [draw, -latex'] \tikzstyle{cloud} = [draw, ellipse,fill=red!20, node distance=3cm,     minimum height=2em]  %\tikzstyle{subroutine} = [draw,rectangle split, rectangle split         horizontal,rectangle split parts=3,minimum height=1cm]  %\tikzstyle{connector} = [draw,circle,...] %\tikzstyle{data} = [draw, trapezium, ...]  \begin{tikzpicture}[node distance = 2cm, auto]     % Place nodes     \node [block] (init) {initialize model};     \node [cloud, left of=init] (expert) {expert};     \node [cloud, right of=init] (system) {system};     \node [block, below of=init] (identify) {identify candidate models};     \node [block, below of=identify] (evaluate) {evaluate candidate models};     \node [block, left of=evaluate, node distance=3cm] (update) {update     model};     \node [decision, below of=evaluate] (decide) {is best candidate     better?};     \node [block, below of=decide, node distance=3cm] (stop) {stop};     % Draw edges     \path [line] (init) -- (identify);     \path [line] (identify) -- (evaluate);     \path [line] (evaluate) -- (decide);     \path [line] (decide) -| node [near start] {yes} (update);     \path [line] (update) |- (identify);     \path [line] (decide) -- node {no}(stop);     \path [line,dashed] (expert) -- (init);     \path [line,dashed] (system) -- (init);     \path [line,dashed] (system) |- (evaluate); \end{tikzpicture}   \end{document} Hey all I downloaded this file () but can't seem to be able to uninstall it. I tried looking online as well as the README file but there is only instruction for installing, not uninstalling the package.   Attempted solutions:  sudo apt-get remove laptop_mode   returned   E: Unable to locate package laptop_mode   but when I type in laptop_mode I do get   Unhandled kernel version: 3.13 ('uname -r' = '3.13.0-32-generic')   Is there any way I can uninstall laptop-mode-tools? Octal number literals: When? Why? Ever? I have never used octal numbers in my code nor come across any code that used it (hexadecimal and bit twiddling notwithstanding).  I started programming in C/C++ about 1994 so maybe I'm too young for this? Does older code use octal? C includes support for these by prepending a 0, but where is the code that uses these base 8 number literals? Difference between the i386 download and the amd64? What is the difference between standard i386 download and the amd64 download of Ubuntu 11.04? I am currently running the i386 on an amd machine, would my system work better with the amd64 download instead? (my machine was running Windows 7 64bit, but I neglected to look at that prior to installing Ubuntu). I would like to install Office 2015/365 on Ubuntu 15.04. I tried to install Office using Wine, but that did not work. Please note that I do not want virtualisation unless it has a -like behaviour, where application windows are treated like regular Ubuntu application windows by the system. Show that computation of all such expressions will result in the same element of $X$ What is "Go" in cribbage? I've played a fair bit of cribbage, but I've never heard of scoring one point for "Go" (as mentioned in this other question: ).  What is it, and what impact does it have on the game? Justifying $\,\Bbb{Z}[i]/\langle 2\rangle\cong \Bbb{Z}[X]/\langle X^2+1,2\rangle\cong \Bbb{F}_2[X]/\langle X^2+1\rangle$ I am asked to describe the quotient ring $\,\Bbb{Z}[X]/\langle X^2+1,2\rangle$ in two different ways. I would say that $\Bbb{Z}[X]/\langle X^2+1,2\rangle$ is isomorphic to $\Bbb{F}_2[X]/\langle X^2+1\rangle$ and $\Bbb{Z}[i]/\langle 2\rangle$ but I am not sure how can I justify that. Does we have $\langle X^2+1,2\rangle=\langle X^2+1\rangle\langle2\rangle$? I think the answer is no, because $\langle X^2+1,2\rangle=2P(X)+(X^2+1)Q(X)$. How can I justify the two isomorphism ? How much money do I need to show as proof of support when applying for a UK Standard Visitor visa? I am an Indian citizen studying in Italy on an Italian visa that expires 19 November, 2015. I have permesso di soggiorno. I want to visit the United Kingdom for my vacations for a week during March. I know the procedures already, however I am a little bit confused about the amount that I must show as a proof of support with my bank statements. I will stay for a week with my friends who are also students in Italy and will be in London for 5 days. What would be the amount in Euros that I need to show for my visit to UK? Methane’s absorption bands are centered at 3.2 and 7.2 microns -- far off the peak of the Planck spectrum for a 290 K blackbody near 16 microns.  Moreover, its absorption bands overlap with the water absorption region.  So why is methane considered a stronger greenhouse gas than carbon dioxide, which has an absorption band at 15 microns?