When we reach a reputation of 15k, we are able to protect a question. Intention behind this privilege is preventing questions from getting non spam answers and low quality answers when the question is too popular.   But when a question is closed (not put on-hold) and there's no possibility of getting answered.         What is the point of adding an option to protect a closed question? Is it a feature intended as a preventive measure so that it will be protected even if a question is later reopened after some modifications?,
Since I've a database systems examination in less than 3 hours (from now), I have been browsing Stack Exchange network for questions with normalisation and related tags. Most of the questions are now closed as  or others from the list.  Since, these questions are closed, no users are allowed to post answers to them (unless they are reopened). Why am I, then, allowed the option to protect such questions? Doesn't that beat the entire purpose behind "protecting" a question?
Why is defragmentation unnecessary? Why is defragmenting unnecessary in Ubuntu? Install GNOME Shell extensions from terminal Is there a way to install GNOME extensions from terminal, for example dash to dock? The way I do it now is to go into Ubuntu Software app store and install it. After viewing episode 5 of season 6 of Game of Thrones, we have come to know that      the Children of the Forest created the White Walkers.   But it seems that the White Walkers attack the Children of Forest. My question is why they would do so, given their origin. Necessary condition for square integrable functions? I'm studying Quantum Mechanics and I came across this which I don't quite understand: For a vector space of functions $f(x)$ to be square integrable (i.e $\int{|f(x)|^2dx &lt; \infty)}$, the necessary condition is $\lim_{|x| \to \infty}f(x) \to 0$. Can someone help me understand why that must be the case? I sort of understand that it must not blow up at the infinities but can a (continuous or piece-wise continuous) function have a non-zero finite value at the infinities and still be square integrable? Trouble understanding the Bohr model of the atom Can I list the resources in a given package? The Fourier transform of a "comb function" is a comb function? Let $f(x) = \sum_{n=-\infty}^{\infty} \delta(x - n)$, where $\delta$ is the Dirac delta function. This function $f$ (a "comb function") is important in signal processing because evenly sampling a function $g$ can be viewed as multiplying $g$ pointwise with $f$. This idea is the first step towards understanding how to approximate the Fourier transform of $g$, given evenly spaced samples of $g$. The next step is to note that $\hat{gf} = \hat{g}*\hat{f}$, where $\hat{f}$ is the Fourier transform of $f$ and $*$ denotes convolution.  Is it true that $\hat f$ is also a comb function? If that statement isn't quite right, what is the correct statement?  I would like to see: 1) an informal, intuitive, nonrigorous but easy derivation of the Fourier transform of $f$ . 2) A rigorous version of the same calculation.  (How would you even define $f$ rigorously, is it a distribution?)  (I'd also be interested in recommendations of math textbooks that cover this topic, including the Nyquist sampling theorem, even if it's only an exercise or series of exercises in an analysis textbook.) When to use "cannot" versus "can't"? When is it best to write "can't" versus writing "cannot"? Are they interchangeable in every situation? Random point uniform on a sphere Its a .vbproj and looks like this  &lt;Project DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003"&gt;     &lt;PropertyGroup&gt;         &lt;ProjectGuid&gt;15a7ee82-9020-4fda-a7fb-85a61664692d&lt;/ProjectGuid&gt;   all i want to get is the ProjectGuid but it does not work when a namespace is there...   Dim xmlDoc As New XmlDocument()  Dim filePath As String = Path.Combine(mDirectory, name + "\" + name + ".vbproj")  xmlDoc.Load(filePath)  Dim value As Object = xmlDoc.SelectNodes("/Project/PropertyGroup/ProjectGuid")   what can i do to fix this? Some conditions require that a person lie in bed all the time until recovered. Is there a name for such conditions or people experiencing them at the moment?   For example,      I am currently &lt;bed sick&gt; and can't help you with your homework.   I tried looking for bed sick but hit a dead end. Is it same number of candies for any stage of evolution while transferring pokemon to professor? I was just wondering if the number of candies we get while transferring the pokemon to professor is same for any stage of evolution ?   For example, you would get a pidgey candy for transferring a pidgey. Is it same number of candies for transferring pidgey, pidgeotto or pidgeot ? What is the relative speed of two near-light speed particles headed towards each other? I understand that nothing can move faster than light due to time dilation. I want to build upon my understanding of Einstein's theory of Special Relativity, so I came up with this hypothetical problem for myself:  If both particles are moving at 0.9c towards each other (according to an observer on Earth), what speed does each particle have relative to the other?  I'm stumped since I am only familiar with Newtonian classical mechanics to solve this (which would be wrong). I am aware of Lorentz' factor $\gamma =\frac{1}{\sqrt{1 - \frac{v^2}{c^2}}}$ and the time dilation equation $t_m = \frac{t_o}{\sqrt{1 - \frac{v^2}{c^2}}}$, but I'm not sure how to apply it in this instance. I'm just looking for a gentle push in the right direction. Edit: My prior research:  This article, ,  talks about the effect of a baseball thrown at 0.9c would have as it traveled towards a batter. This is not what I'm looking for since it doesn't explain the math behind finding the collision speed between two high velocity entities.  This question on Yahoo, , asks a similar question to mine, but no math is involved to demonstrate the calculations behind the reasoning.  This question on Physics.SE, , does not answer my question either. I have not been able to find a similar Physics.SE question which can provide me to clues to my own hypothetical question.  I have also Googled the following phrases:    i. &quot;collision faster than the speed of light&quot; ii. &quot;collision of high speed particles&quot; iii. &quot;lorentz transformation in a collision&quot; iv. &quot;collision analysis at light speed&quot; I need to parse  strings like "2008-09-03T20:56:35.450686Z" into Python's datetime type.  I have found  in the Python standard library, but it is not very convenient.  What is the best way to do this? Polling the keyboard (detect a keypress) in python How can I poll the keyboard from a console python app?  Specifically, I would like to do something akin to this in the midst of a lot of other I/O activities (socket selects, serial port access, etc.):     while 1:       # doing amazing pythonic embedded stuff       # ...        # periodically do a non-blocking check to see if       # we are being told to do something else       x = keyboard.read(1000, timeout = 0)        if len(x):           # ok, some key got pressed           # do something   What is the correct pythonic way to do this on Windows?  Also, portability to Linux wouldn't be bad, though it's not required. Select Input Texture file name as parameter/node How is it that questions posted to the Stack Overflow show up as #1 in Google search results just minutes after being submitted? What SEO practices are being used to generate this sort of up-to-the-minute accuracy? I have a Alcatel onetouch model 50540 running android 5.1.1 as in the title. it is rooted and began uninstalling pre-installed bloatware on my device. I do not have a complete list of uninstalled apps because I had only kept track after the first few, but ill list the ones I do know about    Download Manager Downloads Talkback Hangouts Cricket Wi-Fi Manager Camera Email Onetouch Launcher   That is the essence of what I did. I do have an edited hosts file as a makeshift adblock.  Play store gives me an error code 0 to which I removed app data and tried again, same problem.  I have tried installing local apps which brings up an "app not installed" box.  Lastly I have tried do directly extract the app into /data/app and rebooting which didn't work. What does Use an Object cover? Does anyone know any example that invalidates the following affirmation:     If a morphism $f:A\to A$ induces the identity $\hat f:\operatorname{Spec} \left( A \right) \to \operatorname{Spec} \left( A \right)$ then $f = \operatorname{id} _A $.