I was looking for a way to see what was edited in one of my questions on the Android app, but there doesn't seem to be a way of viewing the edit history.  Is there a way to fo this and if not can we add it in?
Basically this suggestion for the Android app:   Many times I'll see that a post has been edited on the Android app. I'll want to see exactly what was edited, and the Android app doesn't show this. Can the revision history be added to the Android app?
Existence of a local geodesic frame Let $(M,g)$ be a Riemannian manifold of dimension $n$ with Riemannian connection $\nabla,$ and let $p \in M.$ Show that there exists a neighborhood $U \subset M$ of $p$ and $n$ (smooth) vector fields $E_1,...,E_n \in \chi (U),$ orthonormal at each point of $U,$ s.t. at $p,$ $\nabla_{E_i}E_j(p)=0.$  What I've found so far;  Let $V$ be a normal neighborhood at $p.$ Let $(W,x(x_1,...,x_n))$ be a local coordinate system at $p$ s.t. $x(W) \subset V.$  Let $\{X_i:=\frac{\partial}{\partial x_i}\}$ be the standard basis of $T_pM.$ By Gram-Schmidt, there exists an orthonormal basis $\{E_i\}$ of $T_pM.$ Consider the orthonormal frame $E_i(t),$ by parallel transporting $\{E_i(0)=E_i\}$ along a  a geodesic $\gamma :I \to M$ starting at $\gamma(0)=p$ and ending in $\gamma(1)=q,$ where $q \in V.$ This gives us an orthonormal frame at each point of $V.$ To satisfy the second condition, let $E_i(t)=\sum_{l}a_{li}X_l$ and  $E_j(t)=\sum_{s}b_{sj}(t)X_s.$ Then   $$\nabla_{E_i}E_j=\sum_{k}(\sum_{l,s} a_{li}(t)b_{sj}(t)\Gamma^k_{ls}+E_i(b_{kj}))X_k,$$  where $\Gamma^k_{is}$ are Christoffel symbols.   To have $\nabla_{E_i}E_j(p)=0,$ we must have $\sum_{l,s}a_{li}(0)b_{sj}(0)\Gamma^k_{ls}+E_i(b_{kj})(p)=0$ for each $k.$      How can I conclude the argument? I would like to update VirtualBox on my 32 bit Ubuntu 15.04 machine from 4.3.26 to 4.3.28, using a Debian package I manually downloaded from . But simply double-clicking the package opens up the Software Centre which gives an error that installing it would break an existing package (the exact message was:   Breaks existing package 'virtualbox' conflict: virtualbox-4.3 ()   and it does not appear to have an option to ignore this and proceed with the installation anyway. Is there a command-line work-around this problem, perhaps? Which parts are from Eminems real life? In "" we saw how Bunny Rabbit got into the rapping gang and won the heart of millions of rap lovers. Now in Eminem's original life too similar thing happened. We know how Dr. Dre helped him getting into an industry which is dominated by mainly black people in USA. In fact,  called the film semi-autobiographical. So I want to know which parts are direct picturisations of his real life? For some reason, I have a server that if ssh into another server...you don't need to enter the  password.  How is this done? Can someone give me step by step instructions please? How can there be a directory named `~`? I was trying to test out this buggy/new tool to see how it works, and it prompted me to choose a directory to use for stuff I am doing. From the directory ~/Code/indep, I typed in ~/Code/indep/tarbell. (Stupid, I could have just typed 'tarbell', but whatever.) It prompted me to create it because it didn't exist, I said yes. When I inspected the contents of this directory, here is what I see:  brian@navis:~/Code/indep$ ls ~ project1 project2 project3 ...   I thought "oh, weird, it created a symlink to ~". However:  brian@navis:~/Code/indep$ file ./~ ./~: directory   file thinks it's a directory.   brian@navis:~/Code/indep$ ls -l drwxr-xr-x 3 brian brian 4096 Nov  8 16:50 ~ drwxr-xr-x 8 brian brian 4096 Oct 14 18:42 project1 drwxr-xr-x 3 brian brian 4096 Sep 10 21:15 project2 drwxr-xr-x 5 brian brian 4096 Oct 14 19:33 project3 ...   And so does ls -l.   I thought, "oh, ... is it a hard link? I've never really used those." But I tried to reproduce, and it's impossible to create a hard link to a directory. So... I guess I've narrowed this down to things I don't understand. Did I mount my home directory in this other directory somehow?   My main goal at this point is to remove the reference to my home directory in this folder (rm doesn't seem like the answer), but I'm also curious to know what's going on.  EDIT:   In retrospect, I understand exactly what happened. As was answered below, the program created a directory called "~" inside my current directory. The only really obfuscating fact about this is that I wasn't consistent with how I was actually viewing what the directory was. Sometimes I referred to it as  "~" and sometimes as "./~". It's only if you do the latter that you can actually see what's going on, but until I understood this, I was conflating what I was seeing from using the absolute path of "~" to to what was in fact a local directory. Verbatim environment that can break long lines? I want to generate a PDF of user-submitted text using LaTeX. To handle crazy user input, I first thought about using the verbatim package, but of course it doesn't break up too long lines. Is there some package that works similar to verbatim (i.e., accept any input) but formats the text nicely? Is it possible to activate an iPhone 4 without a SIM? Difference between pts and tty Possible Duplicate:          I always see pts and tty when I use the who command but I never understand how they are different? Can somebody please explain me this? Does a car use friction to move? When a car's engine injects fuel into the cylinder chambers, the reaction creates a force that generates rotational momentum to the shaft and over the transmission, it translates that power to the wheels, right?  But, something's bothering me, how does the car actually move, is it dependent on the force of friction? Wheels have a contact with the road in one exact point and when the drive gets to rotate them, a force is exerted on the road in the direction of movement and there is friction that is counteracting it.  Is the key to get a car properly moving to have the drive force equal or less than the force of friction to keep that point locked to the ground and use the rolling of the wheel for translational displacement ie. moving forward? If it's bigger than the force of friction, that would cause the wheels to spin in place?  Am I completely off or am I getting something right? If there's a knowledgeable person on this topic, I'd greatly appreciate some insight, perhaps even a bigger response with some basic vehicle physics. Expectation of momentum in the bound state Is it logically correct to assert that the expectation of the momentum $$\langle \hat p \rangle=0$$ for any bound state because it is bound to some finite region? What is the physical interpretation of the fact that $$\langle \hat p \rangle=0$$ in an energy eigenstate $\psi_n(x,t)$  but $$\langle \hat p \rangle\neq0$$ in some superposition state $$\psi(x,t)=c_m\psi_m(x,t)+c_n\psi_n(x,t)~?$$ Here $\psi_n(x,t)$ the eigenstates of the Hamiltonian, for example, in the problem of particle in a box (say). Question  The test scores of three groups of people are saved as separate vectors in R.  set.seed(1) group1 &lt;- rnorm(100, mean = 75, sd = 10) group2 &lt;- rnorm(100, mean = 85, sd = 10) group3 &lt;- rnorm(100, mean = 95, sd = 10)   I want to know if there is a significant difference in the medians between these groups. I know that I could test group 1 versus group 2 using the Wilcoxon test, like so.  wilcox.test(group1, group2)   However, this compares only two groups at a time, and I would like to compare all three simultaneously. I would like a statistical test that yields a p value at the 0.05 significance level. Could someone please help?  Edit #1 - Mood's median test  Following user Hibernating's suggested answer, I tried Mood's median test.  median.test &lt;- function(x, y){     z &lt;- c(x, y)     g &lt;- rep(1:2, c(length(x), length(y)))     m &lt;- median(z)     fisher.test(z &lt; m, g)$p.value }  median.test(group1, group2)   However, this approach allows me to test for a significant difference between the medians of only two groups at a time. I am not sure of how to use it to compare the medians of all three simultaneously.  Edit #2 - Kruskal-Wallis test  User dmartin's suggested answer appears to be more or less what I need, and allows me to test all three groups simultaneously.  kruskal.test(list(group1, group2, group3))   Edit #3  User Greg Snow helpfully notes in his answer that the Kruskal-Wallis test is appropriate as long as it makes strict assumptions that make it also a test of means. MySQL Conditional Insert robots meta not blocking indexing We have a staging version of our website to test changes on at trailheadpaddleshack.ca/staging1. This never appeared in search before. Recently the staging site has appeared on Google and is affecting our search results.  I'm trying to figure out how the pages got there and how to remove them. The pages have always had &lt;meta name="robots" content="noindex, nofollow"&gt; in the head.  I am kinda new at this but was under the impression this should prevent Google from showing my site in results. I am pretty sure the results appeared in google after I accidently copy pasted some codes from the staging site to the live site that contained links to pages on the staging site. If anyone can point me in the right direction to figure out what happened and prevent it from happening again would be much appreciated.  robots.txt looks like this:  User-agent: * Disallow: /calendar-2/action~posterboard/ Disallow: /calendar-2/action~agenda/ Disallow: /calendar-2/action~oneday/ Disallow: /calendar-2/action~month/ Disallow: /calendar-2/action~week/ Disallow: /calendar-2/action~stream/ #Begin Attracta SEO Tools Sitemap. Do not remove sitemap: http://cdn.attracta.com/sitemap/4035112.xml.gz #End Attracta SEO Tools Sitemap. Do not remove   I also tried adding an X-Robots-Tag header and submited the site to be re-crawled. Did that a few days ago and I still see no changes. Here are the HTTP headers according to "Fetch as Google":  HTTP/1.1 200 OK X-Robots-Tag: noindex,nofollow Vary: Accept-Encoding Transfer-Encoding: chunked Date: Sun, 24 May 2015 16:26:49 GMT Server: LiteSpeed Connection: close X-Pingback: http://trailheadpaddleshack.ca/staging1/xmlrpc.php Content-Type: text/html; charset=UTF-8 Link: &lt;http://trailheadpaddleshack.ca/staging1/?p=170&gt;; rel=shortlink   I am now faced with a bunch of results I need to remove from Google asap as they contain out of date information and are affecting our search results. Webmaster Tools has something for removal of a single URL but I am looking to remove the entire /staging1/ subfolder. Any tips? Show that  the  alternating  group  $A_4$  of all even permutations of $S_4$ does not contain a  subgroup of order $6$.   For me am thinking to write all elements of $A_4$ and trying to find every cyclic subgroup generated by each element of $A_4$, then I have to check whether there exist such a subgroup or not! This is a long procedure for me, I ask if there is a short way to do this. How to stop reordering of the same kind multiple preview windows in task switching? How to securely delete files stored on a SSD? Can $n!$ be a perfect square when $n$ is an integer greater than $1$? Can $n!$ be a perfect square when $n$ is an integer greater than $1$?  Clearly, when $n$ is prime, $n!$ is not a perfect square because the exponent of $n$ in $n!$ is $1$.  The same goes when $n-1$ is prime, by considering the exponent of $n-1$. What is the answer for a general value of $n$?  (And is it possible, to prove without Bertrand's postulate. Because Bertrands postulate is quite a strong result.) Can I visit UK with Italian stay permit? I'm an Egyptian citizen, who holds Schengen visa and stay permit in Italy. Can I go to UK for some days with my stay permit and Schengen visa? If I click to open achievements from a question when I click the X to close the achievements view I end up on the answers tab of the question, I assume because the X is over the tab and it's tapping through.    It appears if I hit the X it's ok, but if I tap anywhere else in the top row (where the X is) then I can switch to the question or answer tab. Is "has or will read" grammatical? I just wrote  in an ELL chat room. But looking at it (or more accurately, listening to my "inner voice" trying to "read it aloud"), I find it bothers me a lot.  A quick check on Google Books finds a claimed 432 written instances of , and 910 instances of , which suggests a significant minority of writers don't have a problem with the fact that the two different read's don't sound the same.  When I check the same construction with other verbs that don't have the same written form for past participle and present tense, it seems people nearly always include both (e.g. :1230, :8; :357, :7).  I'm not usually a big fan of "grammatical rules", but it seems to me there "ought" to be a rule that you shouldn't delete one instance of the verb unless it's "the same" as the one you're keeping. And it also seems to me that since language is primarily spoken, "the same" ought to mean "sounds the same when spoken", not "looks the same when written".  Can anyone who knows more than me about formal rules of grammar settle this one?    As an aside, offhand I can't think of any verb where the past participle and present tense sound the same but are written differently (maybe there aren't any), but would deletion be okay in that case?