How to generate html elements dynamically with Javascript
Event binding on dynamically created elements?
In Java when one interface extends another, why would one redeclare a method in a subinterface? I've been looking at the JMS API from J2EE and found a strange behavior where certain methods that are declared in an interface (e.g., createQueue in Session) are declared again in the subinterfaces such as QueueSession, and with identical documentation.  Since an subinterface "inherits" all the method declarations of the interface it inherits, and since the JavaDoc tool has no problem sorting out the JavaDocs of the subinterface and creating an "inherited operations" list, I can't figure out what this achieves.  The only think of is that initially the call was in Session, and then moved to QueueSession when the specific subclass was created, though then I would have expected to see something in the documentation of the upperclass. But this is just conjecture.  So the question is: Is there a convincing reason to redeclare a method in a subinterface? Why is the gravitational force always attractive? Is there another way to explain this without the curvature of space time?   PS: If the simple answer to this question is that mass makes space-time curve in a concave fashion, I can rephrase the question as why does mass make space-time always curve concavely? What's the best counter strategy against battlecruisers? How should I prepare my army when attacking someone who has 12+ battlecruisers? (Protoss/Zerg/Terran answers are more than appreciated) Find all Quotient (or Factor) Groups of $D_4$ (Dihedral Group of order $8$) I need to be able to find all of the quotient groups for dihedral group 4 with $D_4 = \{ e,R,R^2,R^3,V,H,D,D'\}$. I know I have to start by finding the normal subgroups, which are $\{e,R^2\}$ $\{e,R,R^2,R^3\}$ $\{e,R^2,V,H\}$ $\{e,R^2,D,D'\}$. Then I need to find the sets defined by $G/H=\{ aH : a \in G\}$ with operation $aH  bH = abH$. I am stuck here; could someone please show me how to find all of the factor groups for D4? How do I add a .sty file to my MacTeX/TeXShop installation? I've searched online, but I have not found any clear instructions how to permanently add .sty files to my TeXShop installation. I'm using a Mac with OSX (TeXShop is a mac only program).  What is the best way of doing this? The one comprehensive set of instructions I found .   I've got as far as extracting the files (running LaTeX on the .ins and . dtx files) but after that I don't know what to do. I also don't understand how to update the index of my distribution, and whether there are particular OSX specifics (the instructions are for Windows). What makes some laser beams visible and other laser beams invisible? What makes the beam of some lasers:    visible?  such as the ones used in clubs or such as the laser pointers sold at amazon which if pointed to the sky look like a solid visible beam of light crossing the sky (it reminds me of the lightsaber in Star Wars). invisible?  such as the ones used in pointers for presentations. existence of complex structure in dimension 2 Does an orientable closed 2 manifold always admit a complex structure?﻿  I know that an almost complex doesn' t necessarily give rise to a complex structure(the almost complex structure should be integrable) I am studying 2 manifolds over R, and I wonder if an almost complex structure always exist? This almost structure may be chosen integrable?  I ask because there are certain known results on the different possible geometries in dimension 2.I don' t know exactly how these manifolds (closed and orientable) are classifyied, but I know there are three cases. May be I am confused, and the complex structure is irrelevant to this classification. Some help please! I am a kid trying to teach myself Calculus in order to prepare for next year.   I have the expression  $$\lim_{x\to 2}\frac{\cos(\frac \pi x)}{x-2} $$  There is a hint that says to substitute t for $(\frac \pi2 - \frac \pi x)$ and WolframAlpha evaluates this expression as $\frac \pi4$. However, I got the answer of $1$. Can someone clarify the steps to solving this problem. Is it possible to only allow specific packages updates from a PPA Whenever both my roommate and I use the wifi in a certain room in our apartment, it slows dramatically for me. It doesn't slow for him. If he uses it in another room, it's fine; if I use it in another room together with him, it's fine; it's just in this particular room. Does anyone know of a reason this could be? Does "FN" stand for or mean anything? Can the sum of the first $p$ factorials ever be a perfect power for $\ p>3\ $? Has $$\sum_{j=1}^p j!=q^r$$ , where q,p,r are positive integers, and r > 1 , a solution ?   I solved partially, if r is even, then RHS is a perfect square, and there is no doubt in that. Therefore, the left side must be a perfect square as well. But for p>3, the last digit of LHS is 3 which is not the last digit of any square. Hence, p&lt;4, and hence manually checking, only solutions are p =1,3. But i cannot generalize when r is odd.  Any solution to the next part would be helpful! How can I log into a different Google account? It only shows one of my Google accounts. I want to log into a different one but I don't want them connected in any way. What do I do? Ubuntu 13.10 to 14.04 Lts does not upgrade, keeps showing error The update from Ubuntu 13.10 to 14.04 LTS does not work it keeps showing me an error as could not calculate the upgrade, even when I want it to get updated from the terminal it says the same error. I did not use the beta its the final Ubuntu 14.04 LTS.I have restarted my laptop for like 5-10 times no change. Disabling the software sources also does not help. Configure up-arrow to browse through commands with same initial characters rather than all previous commands On the bash command-line, ↑ gives me the previous command. On the command-lines in ipython or matlab, when I type a few characters, ↑ gives me the previously entered command starting with those characters. How can I enable exactly this behaviour in bash? I am aware of more advanced ways of searching through the command-line history, but sometimes a simple way is more convenient. When & how did Yoda come to know about the Rule of Two? At the very end of Star Wars Episode I: The Phantom Menace, Mace Windu and Yoda had this conversation:     Mace Windu: There is no doubt. The mysterious warrior was a Sith.   Yoda: Always two there are....no more...no less. A master and an   apprentice.   When did he come to know about the secret ? And, how? Any evidence from ? Importing a Single Symbol From a Different Font Is there a general way to change the font of a particular symbol without switching packages?  For example, suppose I'm using Computer Modern for my entire document, but I want the "subset" operator to look as it does in mathabx.  How can I redefine it to appear in this way? Apt sources.list problem , packages not found? I am trying to install WICD but getting following errors on my ubuntu 10.04 box  sudo apt-get install wicd   Err http://archive.ubuntu.schoolnet.lk/ubuntu/ lucid/universe python-wicd 1.7.0+ds1-2   Could not connect to archive.ubuntu.schoolnet.lk:80 (103.29.60.18). - connect (111: Connection refused) Err http://archive.ubuntu.schoolnet.lk/ubuntu/ lucid/main python-iniparse 0.3.1-1   Unable to connect to archive.ubuntu.schoolnet.lk:http: Err http://archive.ubuntu.schoolnet.lk/ubuntu/ lucid/universe wicd-daemon 1.7.0+ds1-2   Unable to connect to archive.ubuntu.schoolnet.lk:http: Err http://archive.ubuntu.schoolnet.lk/ubuntu/ lucid/universe wicd-gtk 1.7.0+ds1-2   Unable to connect to archive.ubuntu.schoolnet.lk:http: Err http://archive.ubuntu.schoolnet.lk/ubuntu/ lucid/universe wicd 1.7.0+ds1-2   Unable to connect to archive.ubuntu.schoolnet.lk:http: Failed to fetch http://archive.ubuntu.schoolnet.lk/ubuntu/pool/universe/w/wicd/python-wicd_1.7.0+ds1-2_all.deb  Could not connect to archive.ubuntu.schoolnet.lk:80 (103.29.60.18). - connect (111: Connection refused) Failed to fetch http://archive.ubuntu.schoolnet.lk/ubuntu/pool/main/p/python-iniparse/python-iniparse_0.3.1-1_all.deb  Unable to connect to archive.ubuntu.schoolnet.lk:http: Failed to fetch http://archive.ubuntu.schoolnet.lk/ubuntu/pool/universe/w/wicd/wicd-daemon_1.7.0+ds1-2_all.deb  Unable to connect to archive.ubuntu.schoolnet.lk:http: Failed to fetch http://archive.ubuntu.schoolnet.lk/ubuntu/pool/universe/w/wicd/wicd-gtk_1.7.0+ds1-2_all.deb  Unable to connect to archive.ubuntu.schoolnet.lk:http: Failed to fetch http://archive.ubuntu.schoolnet.lk/ubuntu/pool/universe/w/wicd/wicd_1.7.0+ds1-2_all.deb  Unable to connect to archive.ubuntu.schoolnet.lk:http: E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing? I installed Ubuntu on my Windows 7 Sager laptop using Wubi. Hibernate (i.e. suspend to disc) is not an option from the power icon, only suspend, shutdown, etc. Hibernate is also not an option from my battery/lid close options. I understand that hibernation is disabled by default in Ubuntu 12.04. I tried running pm-hibernate but I get the following message:  Looking for splash system... none  s2disk: Snapshotting system   and then the computer just hangs with a black screen. According to the documentation  if this fails then I can't enable hibernate but it offers no help in making pm-hibernate succeed.  Could swap be my problem? It looks like I have very small swap:  user@ubuntu:~$ cat /proc/swaps Filename                Type        Size    Used    Priority /host/ubuntu/disks/swap.disk            file        262140  0   -1   The advice on  is only for the author's set up (e.g. I don't have an Ubuntu install disk since I used Wubi) and he says that 'INFO: This will not work for 12.04, resume from hibernate work differently in 12.04.'  Any advice? I really need to get hibernate working to use my laptop as a, er, laptop.  Thanks With $x+y\ge z$ $(x,y,z\ge0)$, prove that: $$\frac{x}{1+x}+\frac{y}{1+y}\ge\frac{z}{1+z}$$  I'm aware that using analytic view this is easy since $f(x)=\frac{x}{1+x}$ is concave in $[0,\infty)$. However I want to prove it using merely algebraic techniques. Is that possible?