Android app: account is not allowed to suggest edits
Android app should send edits to edit queue if necessary rather than rejecting them
I've already done a lot of searching (in particular: ) to try to prove this statement:      $f: A \to B$ is injective if and only if it has a left inverse. [I'm going to also assume $A$ and $B$ are nonempty.]   My attempt so far:     $\Leftarrow$ Suppose $f$ has a left inverse and $f(a_1) = f(a_2)$ for    $a_1, a_2 \in A$. Then there is a function $g: B \to A$ such that   $g\left(f(a_1)\right) = a_1$ and $g\left(f(a_2)\right) = a_2$. Since   $g$ is well-defined, it follows that $g\left(f(a_1)\right) =  g\left(f(a_2)\right)$, and hence $a_1 = a_2$.         $\Rightarrow$Now   suppose $f$ is injective. Then $f(a_1) = f(a_2) \implies a_1 = a_2$.   Furthermore, since $A$ is nonempty, there is an element $x \in A$.   Define $g: B \to A$ by  \begin{equation*} g(b) = \begin{cases}  f^{-1}(b), &amp; b \in \text{Im}(f) \\ x, &amp; b \in A \setminus  \text{Im}(f)\text{.} \end{cases} \end{equation*} This mapping is   well-defined, since if $f$ is injective, $f^{-1}(b)$ is unique.   My main question: does this imply that if $f: A \to B$ is injective that any mapping $g: \text{Im}(f) \to A$ is bijective? Otherwise, I don't understand why we can even use $f^{-1}$ on an element. [Please read the link above for more details - in proof 1.] A and B disjoint, A compact, and B closed implies there is positive distance between both sets Where does "wicked" get its /ɪd/ from? There are three ways I know to pronounce the -ed at the end of an adjective:   /t/ as in cracked. /d/ as in lined. /ɪd/ as in naked   I realise naked is a special case because, as , it comes for Old English nacod, so the suffix isn't added.   shows the pattern of pronunciation of -ed in all other cases. However it doesn't explain why  ends with /ɪd/ (or /id/ or /əd/ depending on the dialect).   that wicked comes from OE wicca, so the d wasn't already there.  Why do we pronounce wicked as /ˈwɪkɪd/ and not /ˈwɪkt/? Chat messages should use consistent icon in iOS app It'd be nice if the chat notifications in the feed used the default Stack Exchange icon like the ones in the inbox do*:     Since items in the feed are grouped so that multiple items from the same site , the site icon helps delimit grouped items a bit less subtlely than the grey divider lines, and chat replies' lack of one causes them to sort of blend in to the previous group.  *Ideally it'd use the icon of the site the room was associated with, but I don't think that information is readily available After seeking clarification about linear model coefficients  I have a follow up question concerning non-signficant (high p value) for coefficients of factor levels.  Example: If my linear model includes a factor with 10 levels, and only 3 of those levels have significant p values associated with them, when using the model to predict Y can I choose to not include the coefficient term if the subject falls in one of the non-signficant level?  More drastically, would it be wrong to lump the 7 non-significant levels into one level and re-analyze? The optical density of a medium is quantified by its refractive index $n$. Does it have any correlation with the mass/number density of the medium? In other words is an optically denser medium must have a greater mass density compared to an optically rarer medium? I would like to see a full how-to guide on how to install Ubuntu. Reference - What does this error mean in PHP? Frequency dependence of electromagnetic reflection I was surprised to see that the Fresnel equations for reflection depends on refractive index and angle of incidence, but they do not depend on frequency. Why is this case? Are they restricted to regions that do not show frequency dependence? How to optimize images to improve pagespeeds / webpage loading times? This is almost a StackOverflow question, however it's completely related to Photoshop and other tools. With every Pagespeed test I do for all my website I get the comment "Optimize images by lossless compressing image X" which often increases my page rank a lot.  I already save EVERY image with 'save for web' with Photoshop, but I was wondering how I could "Optimize images by compressing lossless" even more. As far as I know I'm already doing everything I can.   How can I optimise images to improve my webpage loading speeds? Building a wormhole We regularly get questions about wormholes on this site. See for example  and . Various wormhole solutions are known, of which my favourite is  because it's closest to what every schoolboy (including myself many decades ago) thinks of as the archetypal wormhole.  The trouble is that Visser has pulled the same trick as  of starting with the required (local) geometry and working out what stress-energy tensor is required to create it. So Visser can tell us that if we arrange exotic string along the edges of a cube the spacetime geometry will locally look like a wormhole, but we know nothing about what two regions of spacetime are connected.  My question is this: suppose I construct a Visser wormhole by starting in Minkowksi spacetime with arbitrarily low densities of exotic matter and gradually assembling them into the edges of a cube, how would the spacetime curvature evolve as I did so?  I'm guessing that I would end up with something like Wheeler's bag of gold spacetime. So even though I would locally have something that looked like a wormhole it wouldn't lead anywhere interesting - just to the inside of the bag. I'm also guessing that my question has no answer because it's too hard to do any remotely rigorous calculation. Still, if anyone does know of such calculations or can point me to references I would be most interested. Any way to sync directory structure when the files are already on both sides? I have two drives with the same files, but the directory structure is totally different.  Is there any way to 'move' all the files on the destination side so that they match the structure of the source side? With a script perhaps?    For example, drive A has:    /foo/bar/123.txt /foo/bar/234.txt /foo/bar/dir/567.txt   Whereas drive B has:  /some/other/path/123.txt /bar/doo2/wow/234.txt /bar/doo/567.txt   The files in question are huge (800GB), so I don't want to re-copy them; I just want to sync the structure by creating the necessary directories and moving the files.  I was thinking of a recursive script that would find each source file on the destination, then move it to a matching directory, creating it if necessary. But -- that's beyond my abilities!  Another elegant solution was given here: I don't know so much about coordinate systems...  In my office we use to deal with spatial data coming from archaeological sites. Each site has its own x-y-z coordinate system (GCS). Three simple ortogonal cartesian axis. In the last years we have been managing this spatial data through GIS software (ArcGIS), without using specific coordinate system (just leave it as "undefined")  I'd like to know if there exisits any GCS designed to deal with such datasets using simple cartesian orthogonal axis, without grid distortions of the typical GCS. In addition, I'd like to know if this system is suitable for using it in an online mapping application.  By the way, we manage 2D (ArcMap) and 3D (ArcScene) environments and work with "mm" as length base unit.   If such a thing doesn't exists, maybe someone knows how to create it. Bohr's model of an atom doesn't seem to have overcome the drawback of Rutherford's model A question was asked in one of my friend's interview. The question was to determine the right form from the below sentences.     Q. Correct form of English:          Samuel was with Susan and I   Samuel was with Susan and me   Samuel was with I and Susan   Samuel was with me and Susan   None of these      Now I vaguely remember a rule of thumb from my school days. That is "2-3-1" i.e. where all the persons are acting in a sentence, second person comes first, then third person and it is followed by first person.  So according to this theory, 1 seems to be correct to me. Is this theory correct? Infinity, is clearly not . But there is some dissent on whether or not zero is finite. I have seen authors use "finite" to indicate the value of $0$ is excluded as well as infinity.  Is there any rule about this? If I attempt to change my password to nothing by opening "User Accounts", the "Change" button remains greyed out:    How do I change my password to be empty? I know you can set Ubuntu to automatically log you in, but I want my password to be empty, I never want to type in a password to authenticate myself as that user.  I know that there are reasons why this might not be a good idea, but I want to know if it is even possible. I'm using Ubuntu 12.10. Split Line at Points not splitting at every point in ArcGIS for Desktop? Why does  not split at every point encountered, even if run in an iterative fashion?  Following the suggestions of a thread here and several others, I made a set of points in order to split polylines at specified intervals. In order to do this, I used linear referencing to turn my lines into routes. Then, I exported the attribute table, divided each length by 5, and set points at multiples of 1/5 the length of the line. I used this as the event table to create a layer of events. So, each line has 4 equally spaced points along it, and I thus ultimately need the 5 segments separated by those points.  Curiously, though, when I try to do the second part "Split Line at Point," it seems that only one point is used on a given line at a time, and I'm not sure how it chooses the point (maybe order in its attribute table?) I could run the tool multiple times, but this doesn't seem to solve the problem either. For example, I could see how it would continue splitting segments as more segments are generated, but on e.g. the 4th run I see that some lines are still only split 3 times, even though there is a point within a line segment that was never split and existed before I ran the tool. I'm not sure how the splits are generated, but in any case, it doesn't seem to do what I want it to do, which is produce a split at "each" point.  What should I do to split lines at ALL points along the line? Is there any evidence or reason why FIFA is so against adding instant replay to soccer? I find myself seeing many unlucky or just plain wrong decisions made by refs that could be corrected with instant replay. Where can I see my full list of Questions and Answers in my profile page of Stack Exchange Android App? I want to see all my Questions and Answers in a particular SE site -  - profile page through Stack Exchange Android App. How can I see that? When I tried to see that I found only Top Posts(5) and Top Tags.