Real Projective Space, $\mathbb P^n$, is Hausdorff.
How can I prove formally that the projective plane is a Hausdorff space?
How to mass delete your photos in your iPhone? I cannot do it in the phone itself, neither in iPhoto.  How can you delete all your photos in iPhone? I'm looking for best practice in dealing with scheduled SQL Server Agent jobs in SQL Server 2012 availability groups. Maybe I missed something, however at the current state I feel that SQL Server Agent is not really integrated with this great SQL2012 feature.  How can I make a scheduled SQL agent job aware of a node switch?  For example I have a job running on the primary node which loads data each hour. Now if the primary goes down, how can I activate the job on the secondary which now becomes primary?   If I schedule the job always on the secondary it fails because then the secondary is read-only. I've been informed by those who know much more about Harry Potter than I that Hogwarts is protected with a Disillusionment Charm so all muggles will see is ruins with a "Danger: Keep out!" sign around them.  (Apparently this was in one of the first three books, but I'm not sure where it was.)  My first thought was, "Well, a danger sign would encourage some muggles to investigate!"  Which leads to what I think is an obvious question: Will a disillusionment charm on a place like that still work when a person is real close to the location?  Will it work from inside the location?  For example, if a curious muggle made it to the gates of Hogwarts and started walking around inside, would they still see it as abandon and in ruins, or once they entered, would they see it as it is? I am attempting to set a value in a textarea field using jquery with the following code:  $("textarea#ExampleMessage").attr("value", result.exampleMessage);   The issue is, once this code executes, it is not altering the text in the textarea?  However when performing an alert($("textarea#ExampleMessage").attr("value")) the newly set value is returned? Ubuntu 16.04 multitouch gestures Why split the  tag when writing it with document.write()? Why do some sites (or advertisers that give clients javascript code) employ a technique of splitting the &lt;script&gt; and/or &lt;/script&gt; tags up within document.write() calls?  I noticed that Amazon does this as well, for example:  &lt;script type='text/javascript'&gt;   if (typeof window['jQuery'] == 'undefined') document.write('&lt;scr'+'ipt type="text/javascript" src="http://z-ecx.images-amazon.com/images/G/01/javascripts/lib/jquery/jquery-1.2.6.pack._V265113567_.js"&gt;&lt;/sc'+'ript&gt;'); &lt;/script&gt; Blank questions and answers I have white blank on the posts.    App Version: 1.0.89 Device Manufacturer: Meizu Device Model: m2   OS Version: 5.1 (1464689330)    I can't see the questions and the answers and the comments.  I saw that it's a common issue..  Does it have a fix?   EDIT -  I saw  answer. This answer is ~2 years old. It says that it will fix in the next update.  His version is 1.0.59 - mine is 1.0.89. Huge different.   The problem is still exists! In Radian mode, continually pressing the $\cos$ function of a number causes the result to converge to $x=0.739085133$, a fixed point of $\cos(x)$. Repeating this behavior with the $\sin$ function causes the result to converge to $x=0$, a fixed point of $\sin(x)$.   What happens if this is done using the tan function? It seems that $x=0$ is a repelling fixed point with no convergence in this case.  What would be the best way to explain these results mathematically? System settings is missing System settings is missing. I tried reinstall it as it mentioned , but it seems to be installed and deactivated. This problem occurred when I installed Elementary desktop environment and uninstalled it afterwards. What are the pros and cons of adding a vapor barrier behind shower backer board? After much research, I have a lot of conflicting advise about the need to add a vapor barrier before installing the backer (hardy / cement) board for my bathroom shower. The &quot;expert&quot; at Home Depot, and  seem to think this is a very good idea, and even suggest sealing it with roofing tape.  (The guy on Youtube tapes it directly to the sill of tub.) However, when I asked about the tape and how far down I should go at Lowes, they told me they'd never hear of anyone doing that, and that it didn't seem like a good idea.   Likewise,  putting down caulking on the sill before applying the backer board, and then again after before adding tile, and then caulking a 3rd time under the tiles before grouting. Should I add a vapor barrier between the frame and the cement board?  Why or why not? Just noticed this:  Someone @replied to me in a question which appropriately showed up in my feed.  I go to click on that notice in the feed, and it presents me with "Loading the question failed."  I'd show a picture, but I don't think that it's entirely relevant - I believe it's reproducible if an answer is posted, someone makes a reply, the answer is removed, then that someone else goes back in the feed to try and revisit the post.  Alternatively, why not synchronize the interface between what a 10K user sees on the site, and what they see in the app?  As a 10K user, I would expect to see deleted questions and answers. I've got a PHP script that needs to invoke a shell script but doesn't care at all about the output. The shell script makes a number of SOAP calls and is slow to complete, so I don't want to slow down the PHP request while it waits for a reply. In fact, the PHP request should be able to exit without terminating the shell process.  I've looked into the various exec(), shell_exec(), pcntl_fork(), etc. functions, but none of them seem to offer exactly what I want. (Or, if they do, it's not clear to me how.) Any suggestions? Force LaTeX image to appear in the section in which it's declared Possible Duplicates:           How can I force an image in a LaTeX documents to appear in the section in which I declared it?  I don't want that an image about "Section A" to appear in "Section F". :(  I actually include an image with  \begin{figure}[ht] \begin{center} \includegraphics[scale=0.7]{./img/RobotManipulator3D_WorkSpace.png} \end{center} \caption{3D View of the robotic workspace (in red).} \label{Img:3DRobotWorkspace} \end{figure} Draw a vector with mathematica Can Cycles renders be done from the command line? It seems that Cycles is mainly built in the form of Python scripts (as far as I can tell). Is it still possible to use Cycles to render a .blend file from the command line? Truly destroying a PHP Session? Is it (theoretically) physically possible to project an image into thin air? What temperature should I set my water heater to? Why is inductance (L) proportional with turns-square (N²)? We start from the   $$ \mathbf{\nabla} \times \mathbf{B} = \mu \mathbf{J} + \overbrace{\mu \epsilon \dfrac{\partial \mathbf{E}}{\partial t}}^0. $$  We take surface integration of both sides, for the surface (\$s\$) inside the mean path (\$c\$) of the core.  $$ \int_s \left( \mathbf{\nabla} \times \mathbf{B} \right) \cdot d\mathbf{s} = \mu \int_s \mathbf{J} \cdot d\mathbf{s} $$  We use the  to rewrite the left hand side; where \$c\$ is in the same direction with the magnetic flux \$\Phi\$.  $$ \oint_c \mathbf{B} \cdot d \mathbf{\ell} = \mu N I $$  (The integral on the left hand side results \$NI\$, because there are \$N\$ different wires on the winding.)  The magnetic field density inside these kind of cores are considered to be uniform. So, we can write  $$ B \ell_c \overset\sim= \mu NI \implies B = \dfrac{\mu NI}{\ell_c}; $$  where \$\ell_c\$ is the mean path lenght of the core.  We can find magnetic flux from the magnetic flux density we have found by using the cross sectional area of the core \$A_c\$.  $$ \Phi = BA_c = \dfrac{\mu NIA_c}{\ell_c} $$  By definition, inductance is the amount of magnetic flux generated per applied current, that is  $$ L \overset\triangle= \dfrac{\Phi}{I}. $$  So, we find inductance of the system as  $$ \boxed{ L = \dfrac{\Phi}{I} = \dfrac{\dfrac{\mu NIA_c}{\ell_c}}{I} = \dfrac{\mu NA_c}{\ell_c} }. $$  But, all other sources () give inductance of an inductor like this as  $$ L = \dfrac{\mu N^2A_c}{\ell_c}. $$  What is the mistake I did in my derivation? Please explain in detail. How to install the latest versions of NodeJS and NPM? I noticed over at the  website that node is currently at v 0.12.0.  Can someone let me know how to install the latest version of node together with npm (terminal commands please)?