Posts enter community wiki mode when... the post has been edited ten   (10) times by the original owner. -    Good users occasionally edit their posts to add new info, correct bad info, update the status, fix typos, etc. Many users make legit edits for legit reasons and end up getting their post locked into Community Wiki, ensuring they do no receive reputation for their improved post. A high edit count is more indicative of a user's editing habits than it is of the quality of the post. Can anything be changed to prevent the system from punishing users for improving their posts? Is there a better way to prevent gaming the system by edit-bumping posts?     Voting on a community wiki post (up or down) does not affect any   user's reputation.  -    This post is similar to , but there are a couple reasons this should not be closed as duplicate:   That question was from 2009, and can be considered localized in time Many upvotes were received since that was declined (now +60), begging the issue be reconsidered The problem hasn't been fixed!
I like to edit my answers. To clarify, illuminate, add examples, add links, point to new information as it crops up, etc.  It's highly irritating that my effort to improve my answer turns it into a Community Wiki.  Could anything be done to keep me from turning into a collective?
Combinatorial Proof I have trouble coming up with combinatorial proofs. How would you justify this equality?  $$ n\binom {n-1}{k-1} = k \binom nk $$ where $n$ is a positive integer and $k$ is an integer. Name of component on output side cable of a DC power adapter? What is the name of this component (circled in red) of a charger?    What are the uses of this component? Socket Tester all indicators light up What's the difference between adjusting highlights and shadows in the basic panel and in the tone curve in the Develop Module of Lightroom? I wanted to reduce some highlights in a photo and found that there were two possible ways of doing so: one from the basic panel and another from the tone curve. when I reduce the highlights in one pane the value on the other is unchanged. Are both of them the same thing? Which would be better? The prime example is C# and .Net. 95% of C# questions are also tagged .Net. The reverse isn't the case so it's not a synonym. Basically, C# is a child of .Net.  Would it be possible to create some sort of one-way linkage like this? What was Dolores Umbridge's blood status? Dolores Umbridge's dislike of Muggles, Muggle-born witches and wizards and half-breeds is quite obvious. In Order of the Phoenix she takes a particular dislike to Hagrid due to his giantess mother (and his allegiance to Dumbledore), as well as to the centaur Firenze who takes over as Divination teacher after Professor Trelawney is sacked. And, of course, during Deathly Hallows she is made Head of the Muggle-Born Registration Commission.  In Deathly Hallows, when Hermione (under the effects of Polyjuice potion) comments on the locket she's wearing, Umbridge says this:     "That's - that's pretty, Dolores," she said, pointing at the pendant gleaming in the ruffled folds of Umbridge's blouse.      "What?" snapped Umbridge, glancing down. "Oh yes - an old family heirloom," she said, patting the locket lying on her large bosom. "The S stands for Selwyn... I am related to the Selwyns... Indeed, there are few pure-blood families to whom I am not related. ..."   That seems a rather large and contrived lie to tell just to explain her possession of the locket, considering her blood status had never been questioned by the Ministry. I don't remember it being covered anywhere in the books (which I just recently re-read, so I'd hope I'd remember if it had been!), but I was wondering if there was any other evidence (interviews, etc) to say whether Umbridge was Pure-blood, Half-blood or Muggle-born? Inequality : $\sum_{k=1}^n x_k\cdot \sum_{k=1}^n \frac{1}{x_k} \geq n^2$ I have to show the inequality of $$\left(\sum_{i=1}^n x_i\right)*\left(\sum_{i=1}^n \frac{1}{x_i}\right) \geq n^2.$$For $x_1, ... x_n \in \mathbb{R_{&gt;0}}$ and $ n \geq 1$. I wanted to show this inequality by induction. The basis is clear, but I am not sure how to do the inductive step. Can someone help me with that? How to prove that $P \rightarrow Q$ is equivalent with $\neg P \lor Q $? In my book about Logic, which is called 'Language, Proof and Logic', by the way, there is explained that the conditional $ P \rightarrow Q $ is equivalent with $\neg P \lor Q$.   that gives as answer: 'just compare the truth tables and you can see that they are equivalent'. However, I would like to know how to prove this using formal propositional logic. This should be possible, right? Suppose $K \subset L$ is a finite field extension of degree $m$. Is it true that there exists some natural $n$ such that $L$ is isomorphic to a subfield of $M^{n\times n}(K)$, the ring of $n\times n$ matrices with entries in $K$? What is the smallest dimension (as a function of $m$) for which an isomorphism exists?  The example I had in mind was the 2-dimensional extension $\mathbb{R} \subset \mathbb{C}$ with $\mathbb{C}$ being isomorphic to $\{ \begin{pmatrix}a&amp;-b\\b&amp;a\end{pmatrix} : a, b \in \mathbb{R}\}$. Gedit has a transparent background since upgrade to 16.10 Since I upgraded to from 16.04 to 16.10, gedit has strange new "feature": its background is totally transparent.    Where can this come from ?  Notice I'm using Unity and don't have any specific gnome package installed besides what comes by default. Notice also that in 16.04 I used the Vivacious theme from ravefinity PPA, but I had to go back to Ambiance as Vivacious was broken in 16.10. Maybe it's related.  [EDIT] changing the 'Fonts and Colors' in gedit to any theme other than default (Kate, Solarized, Oblivion, etc..) solves the issue. So there must be a faulty gtksourview file in my home somewhare, but I can't find it... How Can I prove (a+b) mod m = (a mod m) + (b mod m)) mod m? modular arithmetic  How Can I prove (a+b) mod m = (a mod m) + (b mod m)) mod m ? How to copy the contents of a file in UNIX without displaying the file contents. I don't want to cat or vi to see the contents.  I want to copy them to clipboard so that I can paste it back on my windows notepad.  I can't copy the file from that server to another due to access restrictions. Why is a black hole black? I have close to two hundred images where the subject looks like he just walked out of a sauna. It was 36 degrees with humidex, but he was not that red.   For comparison, attaching another picture, same camera, same lens, auto white balance, next day.       So, two questions, 1) how did that happen?, and 2) how do I fix it? I can bring down the red, but then I have to manually bring back the lip color in 200 pictures.   And next time when I deal with an older guy at 36 degrees C I will be shooting indoors.   *Edit: The camera is Olympus EPM 2. I am now guessing that he may have been THAT red, but my eyes tricked me. The last picture is from the beginning of the shoot before he got very hot and had two glasses of wine AND the background worked better for his skin and clothes. I do not have colour management setup, but I will get on it. Debt condition abuse? The rules states that you cannot have two of the same conditions.  You can take a debt condition to gain two additional successes on your influence test to gain assets from the reserve. Thus if you already have a debt, does that mean that you automatically gain two additional successes for each gain asset actions? Evaluating the product $\prod\limits_{k=1}^{n}\cos\left(\frac{k\pi}{n}\right)$ Recently, I ran across a product that seems interesting.  Does anyone know how to get to the closed form:  $$\prod_{k=1}^{n}\cos\left(\frac{k\pi}{n}\right)=-\frac{\sin(\frac{n\pi}{2})}{2^{n-1}}$$  I tried using the identity $\cos(x)=\frac{\sin(2x)}{2\sin(x)}$ in order to make it "telescope" in some fashion, but to no avail. But, then again, I may very well have overlooked something.  This gives the correct solution if $n$ is odd, but of course evaluates to $0$ if $n$ is even.   So, I tried taking that into account, but must have approached it wrong.   How can this be shown? Thanks everyone. We know that the needle that is used in a compass is a permanently magnetized ferromagnetic material and commonly steel is used.  If we used an unmagnetized iron needle instead, would it still align with Earth's magnetic field lines? If yes, how? After upgrading my laptop from karmic to lucid, my fat32 partition won't mount automatically. I get the message:  The disk drive for /osshare is not ready yet or not present Continue to wait; or Press S to skip mounting or M for manual recovery   Funny thing is, if I skip, then /osshare/ is mounted once I log in.   I've a similar setup on my desktop, and it works fine. Fstab on desktop:  UUID=4663-6853  /osshare        vfat    utf8,umask=007,gid=46 0       1   /etc/fstab on laptop:  UUID=1234-5678 /osshare vfat utf8,auto,rw,user 0 0 notify-send not working under ssh Maybe this is answered somewhere else, but I didn't see it.  I am running Ubuntu 14.04. When I SSH into my machine, for example:  ssh &lt;user&gt;@&lt;machineip&gt; notify-send "Hello"   I don't see anything on the monitor where I am logged into the machine. If I prefix notify-send with DISPLAY=:0.0 or DISPLAY=:0 nothing different happens. I just never see any notification on the current session.  Is there some trick/switch to getting this working?  In case this isn't clear, allow me to reiterate: From Computer A, I SSH into Computer B. Within the SSH session, I wish to execute notify-send to run on Computer B. I expect a growl-type notification to appear on the monitor of Computer B. I'm experiencing a bug where when the machine comes back from standby a monitor connected via displayport (MST) does not come back on, however the windows are still in the area it cover if it did come on.  The only way to recover from this short of a restart is to disable and reenable the display now I can do that via the command line just fine but when the display is disabled all the windows get rearranged onto the remaining screen.  Is there a way to persist the window positions and restore them so my script could do this sequence:-   enumerate windows, store positions display off (messing up positions) display on (making the display work again, yay!)  restore position of the windows   I can do step 2 and 3 just fine but I'm lost for step 1 and 4  I know I can force a position per app but that's not what I want as I could be doing different things and have the same apps in different positions, I also have multiple terminals open, I need the current positions storing somehow and restoring.  Any help would be appreciated!