What does "this" mean in jQuery?
How does the "this" keyword work?
What does the tilde (~) mean at the end of a filename? What is the file with the ~ at the end of the filename for?  $ ls # aliased to add flags -rwxrwxr-x  1 durrantm  2741 May 16 09:28 strip_out_rspec_prep_cmds.sh~* drwxrwxr-x 13 durrantm  4096 May 16 14:21 ../ -rwxrwxr-x  1 durrantm  2221 May 16 14:58 strip_out_rspec_prep_cmds.sh*   This is not the same as .swp files which are there while editing.  The two files have quite a few differences and the newer file (no ~ at the end) has the most recent changes and those changes are not in the older (~) file.  Looks like I can delete it? Number of ring homomorphisms from $\mathbb Z_{12}$ to $\mathbb Z_{28}$. Question:      Find the number of non trivial ring homomorphisms from $\mathbb Z_{12}$ to $\mathbb Z_{28}$. ($f$ is not necessarily unitary, i.e., $f(1)$ need not be $1$.)    Suppose $f$ is a ring homomorphism from $\mathbb Z_{12}$ to $\mathbb Z_{28}$.  Consider $f$ as a additive group homomorphism.  Let $k= |\ker f|$ and  $ t = |\operatorname{im}(f)|$. Then $k\mid 12$ and $t\mid 24$ and $kt=12$, by first isomorphism  theorem of groups.  There are two possibilities $k=3$, $t=4$   and $k=6$, $t=2$.  For the first case $f$ should map $1$ to an element of the subgroup generated by $7$ as there is a unique subgroup of $\mathbb Z_{28}$ of order $4$ generated by $7$. For the second case $1$ has to map to $14$, for the same reasoning.  So there are at most two ring homomorphisms from $\mathbb Z_{12}$ to $\mathbb Z_{28}$. Question is how to check the possible maps which are ring homomorphisms.  Thanks. Word or expression for "someone using fake kindness to hide something or his true nature" I installed jockey-gtk but how do I run it? zuber@zuber-pc:~$ sudo apt-get install jockey-gtk   Reading package lists... Done Building dependency tree        Reading state information... Done The following packages were automatically installed and are no longer required:   nvidia-common python-xkit Use 'apt-get autoremove' to remove them. The following NEW packages will be installed:   jockey-gtk 0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded. Need to get 0 B/3,158 B of archives. After this operation, 53.2 kB of additional disk space will be used. Selecting previously unselected package jockey-gtk. (Reading database ... 156414 files and directories currently installed.) Unpacking jockey-gtk (from .../jockey-gtk_0.9.7-0ubuntu11_all.deb) ... Setting up jockey-gtk (0.9.7-0ubuntu11) ... zuber@zuber-pc:~$ jockey-gtk The program 'jockey-gtk' is currently not installed. You can install it by typing: sudo apt-get install jockey-gtk   And this not only occur with jockey-gtk. I have same problem with synergy(I did not tried with other software). Is it known problem or am I only one? How do I fix it? Best way to start investing, for a young person just starting their career? Can't use String#trim as a callback for Array#map How to automatically reinvest in non-dividend paying funds I've read Einsteins quote stating "The most powerful force in the universe is compound interest." However, everywhere I read this is basically only possible with dividend paying stocks and then applying a dividend reinvestment plan.  Is there a re-investing strategy like this for non-dividend paying mutual funds (or even non-dividend paying stock)? I figured that the only way would be to sell all your funds and then buy x+1 funds again, but this would cause a big loss because of transaction costs from the broker. Title says it all I looked for a proof on this site but couldn't find one.  Prove if $f$ is analytic on $D$ and $g$ is analytic on $\Omega$ containing the range of $f$ show $g(f(z))$ is analytic.  The statement seems obvious but I can't seem to be able to prove it. What do the words 'RELATED' and 'ESTABLISHED' individually signify in RELATED,ESTABLISHED state in iptables? Is a music band a singular or a collective entity, grammatically speaking? Duplicate:    What is correct to say?  Korn* is a great band  OR  Korn* are a great band.  (* You can replace your favourite band's name here) Of course everybody there is no doubt about the following sentences:  The Beatles are a great band Led Zeppelin is a great band  But with certain kinds of names, the situation becomes difficult.  Metallica are a great band  OR  Metallica is a great band  Is there any consensus on this matter? How do I set up shared folders in a Windows Virtualbox guest? I have installed VirtualBox OSE on Ubuntu 11.04 and Windows XP pro as the virtual machine. Now I want to have a shared folder which can be accessed on both, my host Ubuntu machine, and my WinXP guest virtual machine.  How can I do that? Producing .bbl file with Lyx and JabRef How do I produce the .bbl file required for arXiv using JabRef for bibtex and Lyx? Remember all opened files with split windows and their positions in Emacs Is it possible to have several different views of one scene and set them as named "presets"? I was wondering whether the time shown is the time I would be arriving in France so its time zone etc.  I know France is an hour ahead so not sure if I'm right in my assumption... It would be useful to know as I plan on traveling to the States and other European countries soon as well. We know that $221 = 17*13$. So we can check if the system has roots to both of those equations separately, which it does:  $x^{5} \equiv 2$ mod $13$ has the solution $6 + 13n$ and $x^{5} \equiv 2$ mod $17$ has the solution $15 + 17n$.   I got these numbers from wolfram, I have no idea how to solve this problem WITHOUT a calculator. And even after finding these numbers. How would one obtain a solution modulo $221$? I was thinking the Chinese Remainder Theorem but I am under the assumption that CRT only applies to problems with powers of $x$ which are $1$.  Thanks. In wikipedia FKT algorithm is given for planar graphs. Not anything for complete graphs. I need to find the number of perfect matchings in complete graph of six vertices. Trying to purge MySQL fails I'm running in circles currently, trying to fix some mysql problem.  I couldn't use apt-get for a while now, because it always stuck at the line Setting up mysql-server-5.6 (5.6.27-0ubuntu0.15.04.1) ... and didn't let me do anything. So I tried to reinstall mysql, purging it. While I was able to remove mysql-server and mysql-client eventually, I'm still unable to purge mysql-common. Obviously, I managed to corrupt something, but how can I get my system back and running at this point?  ...:~# apt-get purge mysql-common Reading package lists... Done Building dependency tree        Reading state information... Done The following packages will be REMOVED:   mysql-common* 0 upgraded, 0 newly installed, 1 to remove and 5 not upgraded. After this operation, 0 B of additional disk space will be used. Do you want to continue? [Y/n] Y (Reading database ... 423600 files and directories currently installed.) Removing mysql-common (5.6.27-0ubuntu0.15.04.1) ... Purging configuration files for mysql-common (5.6.27-0ubuntu0.15.04.1) ... update-alternatives: error: /var/lib/dpkg/alternatives/my.cnf corrupt: invalid status dpkg: error processing package mysql-common (--purge):  subprocess installed post-removal script returned error exit status 2 Errors were encountered while processing:  mysql-common E: Sub-process /usr/bin/dpkg returned an error code (1)   -  ...# sudo dpkg -P --force-all mysql-common (Reading database ... 424733 files and directories currently installed.) Removing mysql-common (5.6.27-0ubuntu0.15.04.1) ... Purging configuration files for mysql-common (5.6.27-0ubuntu0.15.04.1) ... update-alternatives: error: no alternatives for my.cnf dpkg: error processing package mysql-common (--purge):  subprocess installed post-removal script returned error exit status 2 Errors were encountered while processing:  mysql-common   -  ...:~# lsb_release -a No LSB modules are available. Distributor ID: Ubuntu Description:    Ubuntu 15.04 Release:    15.04 Codename:   vivid   My goal is to just get it back and running again (mysql). How can we recover the Newtonian gravitational potential from the metric of general relativity? HTML table headers always visible at top of window when viewing a large table