How to manually write an element of group ring in GAP.
GAP: how to work with elements of the group ring of the symmetric group $\mathbb{C}[S_k]$?
I am looking to use this feature for two purposes: scanning books (one camera pointed at each of a pair of pages), and for stereo 3D photography.  I would like to be able to preview and capture photos from two cameras simultaneously, and download them to my Mac (recent laptop, Mac OS X 10.8.x). Being able to keep track of which photos were from which camera is also a must.  I see a couple of packages that will do this via USB tethering on Windows, namely  (which other than being on Windows, looks perfect for my needs) and . I certainly could run Windows on my Mac somehow, but I'd rather avoid that, if possible.  I haven't bought the cameras yet, and I do not have any requirements as to which cameras are supported (it seems the packages above only support Canons), other than that they be relatively inexpensive. This is a hobby-type project, not a $3000 dSLR-type project.  However, even if all you have is a dSLR solution for this problem, I'd still like to hear about it. Perhaps it will lead to related solution.  Inventive hacky solutions welcome! pm-hibernate freezes and/or fails to resume on Dell XPS 13, 14.04, 3.19 kernel I'm running 14.04 on a new XPS 13. In order to support the newer hardware, I'm running a mainline 3.19 kernel.   Hibernate resume has been iffy with the entire 3.19 kernel line, but recently (3.19.5) pm-hibernate no longer works at all. The screen will either a) switch off momentarily, then back on with all inputs frozen or b) switch off entirely, and fail to resume upon power on (despite displaying the correct resume-from-uuid message).  I have enough swap space (and it has worked in the past), I have checked that the uuid is being correctly referenced, and nothing seems particularly amiss in /var/log/pm-suspend.log (last 200 lines here: )  Thanks for your help. Why does parameter expansion with spaces without quotes work inside double brackets "[[" but not inside single brackets "["? I have two laptops: Dell xps M1210 and Dell vostro 1400. On MS windows the output volume is so loud that I just need to set volume to around 20% to listen music and watch videos. I use Bose TriPort In-Ear Headphones most of the times. On ubuntu, even if I set 100% volume on the multimedia player, on the desktop volume manager as well, and also on the ncurses GUI of alsa mixer, I get very low volume output. Sometimes while playing some vidoes the volume is so low that I barely hear any words. I have struggled for two years since I started to use ubuntu to solve this mystery. The same sound card which gives excellent sound on MS windows fails miserably on GNU/Linux. Few weeks back I bought an Asus 100PX EEE PC. To my surprise even it also has the same issue. I have tried many versions of ubuntu and also I have done manual compiles of alsa modules without any success. I have asked and read about it in every possible forums and howto's. Nothing has helped me to address the issue. Looking for an appropriate English name to replace my Chinese name Background: I am Chinese, and after living abroad from China for several years, I realize that I need an English name anyway. I’ve seen too many confused faces looking at my Chinese name. My Chinese Name: I am male, my Chinese first name is (IPA): /ʃəʊ/-/dəʊ/, and my family name is: /dʒi/. (Check ipa-reader.xyz if not clear.) Any advice about what could be a good idea of a first name, if the last name sounds like &quot;G&quot;? Something about myself: I'm a introvert, nerdy person. I don't like social, small talk, public area. I enjoy programming, writing, arguing. Physically I am short, slim, with a huge glasses. Evaluate $$I=\int_{0}^{1}\frac{x\log x}{\log(1-x)}dx$$   I try to change it to:$$I=\int_{0}^{1}\frac{(1-x)\log(1-x)}{\log x}dx$$ but I can't do next steps,help me ,thank you very much. Can you restore log file backups to a mirror database after failure? Purely a theoretical question as I've been considering possible DR scenarios...  In this scenario:   The link between a principle and a mirror server becomes unavailable for a period of time (e.g. network outage) Incremental log backups are still being taken during this time Then the principle database fails and is unrecoverable   Is it possible to restore the incremental log backups onto the mirror to bring it up to date and back online, or would you need to start from scratch with a restore of a full backup?  Depending on the size of the database the difference could be hours of downtime so it would be nice to know.  I'm predominantly interested in SQL Server 2008 R2 and 2012 but other people may be interested in other versions if there's a difference. Package incompatibilites: etoolbox, hyperref, and bm, standalone? I am trying to transition to using the etoolbox package, but seem to have run into some difficulties and they appear related to the hyperref and bm packages which to me seem totally unrelated.  The MWE example compiles since \RemoveEToolbox is defined and shows that there is no apparent problem before etoolbox was used.    Commenting out the \def\RemoveEToolbox{} line produces two problems:   With both the \renewcommand, and the usepackage{hyperref} commented, this results in "Runaway argument? Paragraph ended before \bm@test@token was complete". Including the usepackage{hyperref} (with \renewcommand commented) results in "Undefined control  sequence. \Call@AtVeryEndDocument ...cumentHook \@undefined"   But if uncomment the \renewcommand{\bm}{#1} line (effectively doing without any \bm), then this seems to compile.  I have been using this for a while now and things appeared to have been working fine, but now that I attempt to use etoolbox I seem to run into problems.  \documentclass{standalone} \def\RemoveEToolbox{}% Shows that this works fine without {etoolbox}  \usepackage{amsmath} \usepackage{xcolor} \usepackage{bm}  \ifdefined\RemoveEToolbox     \newcommand*{\iftoggle}[3]{#2}% Default to true value of "if" \else     \usepackage{etoolbox}     \newtoggle{paper}     \toggletrue{paper}      %\renewcommand{\bm}[1]{#1}% Why can't I have a normal \bm with {etoolbox}? \fi  % \usepackage{hyperref}  \begin{document}  This document is intended for  \iftoggle{paper}{paper}{electronic} distribution.  \bm{\textcolor{blue}{Solve $x^2-1=0$}}  \begin{align*}     a &amp;= b\\     \iftoggle{paper}{         c &amp;= d\\     }{}     e &amp;= f\\ \end{align*} \end{document} Filter subscription email is not being delivered (June 2019 - Feb 2020) I have created a custom filter in  and specified that I would like to get email updates:  However, I never got a confirmation mail nor any notifications based on my filter. I tried the &quot;resent confirmation mail&quot; button on the right hand sidebar:  But again nothing happens. The mail address should be fine  I used it for all kinds of notifications from Stack Exchange. For example the rep recalculation email arrived just fine on this address.  I retyped it several times to make sure there really isn't any typo  I double checked that it did not end up in the spam filter  I don't think it is a problem with my particular email provider, users with other mail providers seem to have the same problem, see     This is possibly related to , but this claims to be &quot;status complete&quot;.   EDIT: Although the &quot;status-completed&quot; tag was added, the problem still persists  EDIT 2: As of Feb 2020, it finally works How to correctly add a path to PATH? I'm wondering where a new path has to be added to the PATH environment variable. I know this can be accomplished by editing .bashrc (for example), but it's not clear how to do this.  This way:  export PATH=~/opt/bin:$PATH   or this?    export PATH=$PATH:~/opt/bin Ask to install program after "The program 'x' is currently not installed" If you try to execute a program that is not installed you will get a message  The program 'x' is currently not installed. You can install it by typing:  sudo apt-get install x   and instead of offering you to install the program for you, you have to type the actual command. How can this behavior be changed? Keep the message ID in the text field so I can reply to a message with an upload Is "The empty set is a subset of any set" a convention? Suppose $p$  and $p^2+2$ are prime numbers, prove that $p^3+2$ is also a prime number. Actually I do not know what is the relationship among square numbers, cube numbers and prime numbers Convert XML/HTML Entities into Unicode String in Python Should I buy a Canon 55-250mm lens or 70-300mm for my Rebel T3i? I have the basic 18-55mm lens that came with my camera but I need a next step up that's not too expensive.   What are the most common types of photos shot with either lenses? Or what is each lens best for? Is "mens" a valid word? I've been living in Ireland for almost a year now and I start noticing they use the word "mens" a lot. I can see it used in:   Shops, to denote the area where you can find men's clothes In sport, when they talk about "mens team".    My guess is just that they are lazy about the use of quotes, so that mens should actually be men's. However, there may be some rule I'm not aware of. So, is "mens" only limited to Irish English? When I'm allowed to use it? Taking the second derivative of a parametric curve I understand that for the parametric equations  $$\begin{align*}x&amp;=f(t)\\   y&amp;=g(t)\end{align*}$$  If $F(x)$ is the function with parameter removed then $\displaystyle F&#39;(x) = \frac{\text{d}y}{\text{d}t}\big/\frac{\text{d}x}{\text{d}t}$  But the procedure for taking the second derivative is just described as " replace $y$ with dy/dx " to get   $$\frac{\text{d}^2y}{\text{d}x^2}=\frac{\text{d}}{\text{d}x}\left(\frac{\text{d}y}{\text{d}x}\right)=\frac{\left[\frac{\text{d}}{\text{d}t}\left(\frac{\text{d}y}{\text{d}t}\right)\right]}{\left(\frac{\text{d}x}{\text{d}t}\right)}$$  I don't understand the justification for this step. Not at all.   But that's all my book says on the matter then it launches in to plugging things in to this formula, and it seems to work well enough, but I don't know why.  I often find answers about question on differentials are beyond my level, I'd really like to get this, it'd mean a lot to me if someone could break it down. How to get a JavaScript object's class? Possible Duplicate:          This is a line spoken by the . I always wondered if this is grammatically correct.  Luke says something like "You are mistaken ..." which the Emperor answers with     No, it is you who are mistaken!   Why wouldn't he say     No, it is you who is mistaken!   instead?  I don't know what rules apply here but my stomach tells me the latter is (at least also) correct, although you would say "you are mistaken". It feels as if he should be referring to "you" in the third person.  Could you please shed some light? Are both correct or – if not – which one is correct? And why?