For example, if someone asks this question:     I'm getting an error doing X. Why?   A possible answer could be:     You need to do Y to avoid getting this error.    If Y is a technique or tool and if Y has a tag, should I edit the question to add the  tag? It seems correct because specialists in  will be able to find the question and add more useful information.  However, I can see two issues:   If  or  is also a possible solution, the question will have many distinct tags.   Example  Question:     My PC is freezing. What should I do?   Answer 1:     You need to run an anti-virus to remove malwares.   Answer 2:     Your PC may be overheated. Check if your fan is working correctly.   So, in this case, should I add  +  to the question?     If the question is marked with , the OP will look a bit dumb for asking something that is quite obvious if you see the tag.   Example  Question:     What series is it?   Answer:     This is "Game of Thrones".   Adding a  tag would make the OP to look dumb.  Another example for this would be:  Question:     How can I securely store an user password?   Answer:     You should hash the password before storing it.   In this case, should I add the  tag?     So, how should I proceed? Is there a generic guidance?
Here's a scenario:  Someone asked about "How to build a SQL query to get count and blah blah blah..."  His only tag is . I added the  and  tags to it.  Someone else answered with a nice SQL statement that has a "group by" statement which seems "logically inevitable".  I proceed to add a tag . I did that on the basis that someone who searches for  will be able to find this post useful, just as I did. My concern is, it wasn't described at all in the question, nor was it implied, unlike  and .  What is the community opinion?  The scenario above is a real one . And the one who answered it nicely is Jon Skeet.
Why isn't  generic?    Seems like Collection&lt;E&gt; could have boolean remove(E o);   Then, when you accidentally try to remove (for example) Set&lt;String&gt; instead of each individual String from a Collection&lt;String&gt;, it would be a compile time error instead of a debugging problem later. Could I have a hint for testing the convergence of the following series please?  $$\sum_{n=2}^\infty\frac{1}{(\ln n)^{\ln n}}$$  I am very appreciative for your help. Let $\alpha = \frac{1+\sqrt{-19}}{2}$. Let $A = \mathbb Z[\alpha]$. Let's assume that we know that its invertibles are $\{1,-1\}$. During an exercise we proved that:     Lemma: If $(D,g)$ is a Euclidean domain such that its invertibles are $\{1,-1\}$, and $x$ is an element of minimal degree among the elements that are not invertible, then $D/(x)$ is isomorphic to $\mathbb Z/2\mathbb Z$ or $\mathbb Z/3\mathbb Z$.   Now the exercise asks:     Prove that $A$ is not a Euclidean Domain.   Everything hints to an argument by contradiction: let $(A, d)$ be a ED and $x$ an element of minimal degree among the non invertibles we'd like to show that $A/(x)$ is not isomorphic to $\mathbb Z/2\mathbb Z$ or $\mathbb Z/3\mathbb Z$.  How do we do that? My problem is that, since I don't know what this degree function looks like, I don't know how to choose this $x$!  I know that the elements of $A/(x)$ are of the form $a+(x)$, with $a$ of degree less than $x$ or zero. By minimality of $x$ this means that $a\in \{0, 1, -1\}$. Now I'm lost: how do we derive a contradiction from this? Exact relationship between electric field and intensity I often see $I(t)\propto |E(t)|^2$. What is the exact form ? Which constants are missing to make this an equality and why are they so often omitted ? Is there an equivalent of MATLAB's Workspace window in Mathematica? How to revert to GNOME Classic Desktop? The identification of an electron as a particle and the positron as an antiparticle is a matter of convention. We see lots of electrons around us so they become the normal particle and the rare and unusual positrons become the .  My question is, when you have made the choice of the electron and positron as particle and anti-particle does this automatically identify every other particle (every other fermion?) as normal or anti?  For example the proton is a particle, or rather the quarks inside are. By considering the interactions of an electron with a quark inside a proton can we find something, e.g. a conserved quantity, that naturally identifies that quark as a particle rather than an antiparticle? Or do we also just have to extend our convention so say that a proton is a particle rather than an antiparticle? To complete the family I guess the same question would apply to the neutrinos. Reading the extension of files in a directory with Java? Books for particle physics and the Standard Model How to mix a jpeg background image with a 3D scene generated using Filmic Blender? I want to compose 3D-model over image, and I use filmic to get more suitable result. But I want the background image to remain in the original colors. So I try to use this setting:    but it haven't setting "look" ("high contrast", "low contrast", ets..) here, so color changes..  How to solve this?  Of course, I can save my render and compose it with jpg-image in different place - no problem here, but my question is about how to make it in place. It will give ability to control colors in filmic color space and see the results immediately.   UPD: image is from image node:    UPD2:     you can't really convert a display referred image to the scene   referred domain; the information has been permanently lost   Ok, but how to make the colors at the output looks close to the original?  UPD3:  This filmic version is from daily build. I know that I can create/burn bootable CD/DVD or live USB and can boot/install from it. But suppose I am currently running GNU/Linux and I've ISO file of another GNU/Linux that I want to install on my hard disk, then Can I directly boot from ISO from hard disk and try/install that GNU/Linux operating system? Electromagnetic waves in vacuum If there is no source then also there is electromagnetic waves described by Maxwell equation. how if there is no source then existence of EM waves. What gives energy to this EM  waves. Is it vacuum fluctuation or something else? I unlocked the 'Files' button/icon from my unity launcher and now it disappearead and I cannot restore it or get it back I unlocked the 'Files' button for the Ubuntu file manager from the unity launcher and I cannot get it back.   When I run the file manager from the dash, the icon does not appear on the launcher like it does for all other applications while they are running. I wanted to have an empty launcher when no applications are running, and just have the icons of those I am actively using there.  Any idea why I don't see it in the launcher when its running or how to lock it back? I'm planning to visit a summer school in the Schengen zone. What kind of visa should I apply for? I will be attending a summer school which will last 10 days.  I want to know: for applying for a Schengen visa, is the purpose of my trip considered as touristic or study? How to filter a list by hour Use of definite article before phrases like Heathrow Airport, Hyde Park, Waterloo Station, Edgware Road and Parliament Square An idempotent operator is compact if and only if it is of finite rank How to enable default file manager(nautilus) to handle desktop icons Python: Invalid Token Can a shadow move faster than the speed of light? I'm just a layman with no real science background  (a) I'm not really sure what a shadow is. Some people are saying that it's the absence of something (a photon?) and therefore it is not subject to laws of physics. But I know when I'm in a shadow and when in sunlight... that's "information", and I thought that information flow can't break the speed of light limit.  (b) Some others use the laser pointer/flicking wrist example to talk about laser dots moving faster than light speed. But that can't be right, can it? The photons from the laser point have to travel from A to B and (after wrist flick) from A to C ... but the photons are all moving at the speed of light - there's no law-breaking in moving the laser dot from point B to point C because the photons are moving either from A to B or A to C ... the distance from B to C is not material (is it?).  (c) Also, can a shadow be thought of as a gap in a photon flow? E.g. if I interrupt a beam of single photons then can I think of it as e.g. PPPSSSPPPSSSPPPSSSPPP, etc where P = photons and S(shadow) = no photon &amp;, if so, the "SSS" is effectively travelling at the speed of light ... no faster.