Surjective implies right inverse
$f$ is surjective iff it has a right inverse: using the axiom of choice and errors in ProofWiki
Where are the images from  coming from?  Where are they being saved on my system?  Is there any way for me to point this at my own source of images? How to rank a million images with a crowdsourced sort How can I get the size of an array from a pointer in C? how to disable system apps without root? How to disable system apps without root?  My phone model is vivo x5 max+ and android 4.4.4  I have tried Debloater but it failed to connect (I am sure I've allowed USB debugging). Fred and George Weasley are known for their trouble-making and general &quot;solemnly swearing they are up to no good&quot;. Their antics/adventures give something to smile about and show us not all wizards are as serious as Professor McGonagall and Hermione. This gives them a reputation of being less intelligent and indeed they only achieved three OWLs. However, we also see the twins have quite a brilliant side! Being able to open and successfully run a shop in Diagon Alley without having completed their Hogwarts education is no easy take (IMO, anyway). Their creations helped students get out of class, our heroes out of tight spot, and even stop our enemies execute an evil plot. Ginny may have said it best:  &quot;We’ve been hearing explosions out of their room for ages, but we never thought they were actually making things,&quot; said Ginny. &quot;We thought they just liked the noise.&quot; Harry Potter and the Goblet of Fire  Do we know how many things Fred and George invented? systemctl --user not available for www-data user systemctl --user seems to be working fine for the desktop user:  dev@dev-VirtualBox:~$ systemctl --user &gt; /dev/null dev@dev-VirtualBox:~$ echo $? 0   But when running the same command under the www-data user I get an unexpected response  dev@dev-VirtualBox:~$ sudo su www-data -s /bin/bash www-data@dev-VirtualBox:~$ systemctl --user &gt; /dev/null  Failed to connect to bus: No such file or directory  www-data@dev-VirtualBox:~$ echo $?  1   How to enable systemctl --user here?  Running Ubuntu 16.04 What exactly are DLL files, and how do they work? How exactly do DLL files work? There seems to be an awful lot of them, but I don't know what they are or how they work.  So, what's the deal with them? "My wife and I's seafood collaboration dinner" I just stumbled upon a :     My wife and I's seafood collaboration dinner. How does it look?   Sure enough, the top comment immediately points out that it should be "my wife's and my". However, a cross-post to the Grammar subreddit produced :     It's fine as it is written. "my wife and I" is a noun phrase, functioning as a subjective pronoun in the singular and made possessive with the apostrophe. It is exactly the same as "our".      It seems weird because you would never use "I's" on its own but it is not on its own here - it is part of a noun phrase.   That's a rather intriguing argument. Does it hold any water? Why does Spring MVC respond with a 404 and report "No mapping found for HTTP request with URI [...] in DispatcherServlet"? Can you cast a 9th level spell if your multiclass spell slots have 9th level spell slots? Why didn't Dumbledore prevent the prosecution of Sirius Black? Dumbledore performed the Fidelius charm on the Potters, so he knew who the Secret-Keeper was1. That implies he knew not Sirius but Wormtail betrayed the Potters. Why didn't he prevent Sirius's conviction and suspect the explosion killing twelve Muggles was caused by Wormtail (and that Sirius cornered Wormtail instead of the other way around)?   1: Though in  it is said Dumbledore didn't know. I find it hard to believe the person casting the Fidelius charm doesn't know who the Secret-Keeper is. Does SOQL join not respect OWD /sharing settings? A->B are two objects connected using lookup relationships. If somehow, I get read only access to child record but do not have access on parent record then still i am able to see data from parent record through formula fields. Similarly will SOQL in Apex also allow me to fetch fields from parent record regardless of using 'WITH Sharing ' keyword at class level? What if the LHC doesn't see SUSY? A question in four parts.   What are the main problems which supersymmetry purports to solve?  What would constitute lack of evidence for SUSY at the proposed LHC energy scales (e.g. certain predicted superpartners are not in fact observed)?  Are there alternative theoretical approaches which would address the SUSY problem set and which would still be credible in such an LHC no-SUSY-scenario? Where would LHC-disconfirmation of SUSY leave String Theory?   I would like to think that these four points could be taken together as one question. Getting around the FAT32 4GB file size limit $\aleph_1$ is the cardinality of the countable ordinals. It is the least cardinal number greater than $\aleph_0$, and assuming the continuum hypothesis it's equal to $\mathfrak{c}$, the cardinality of the the real numbers.    My question is, is it possible for all $\aleph_1$ subsets of $\Bbb{R}$ to have Lebesgue measure $0$?  This is, of course, impossible assuming the continuum hypothesis, because then all sets of real numbers would have measure $0$, which is absurd.  But is $\mathsf{ZFC}$ + $\lnot\mathsf{CH}$ + "all subset of $\Bbb{R}$ of cardinality $\aleph_1$ have Lebesgue measure $0$" consistent?  If not, what if we replaced Lebesgue measure with some other measure?  It may be worth noting that, although there may be subsets of $\Bbb{R}$ with cardinality $\aleph_1$, there are no subsets of $\Bbb{R}$ which have the order-type $\omega_1$ (the order-type of the countable ordinals) under the usual ordering on $\Bbb{R}$.  Any help would be greatly appreciated.  Thank you in Advance. Dimensional Tolerance for US Standard NEMA 1-15 Plugs I am trying to find the dimensional tolerance on US electrical plugs. I have tried looking online, but I have only been able to find that they are called , and have found the picture below showing length and height for the male connector (but not width of the male prong), and I haven't been able to find dimensional tolerances anywhere.     I ask here because I'm assuming there's a US code that governs electrical plugs, but I can't seem to find the standard anywhere. How can I get a specific Floor in my Tower? I really really want a specific floor () in my Tiny Tower.  How does the game decide which exact business will go into the "Creative" floor?  Do I have to meet requirements (such as tower height) to unlock certain floors? Scenario:   Create SymLink: C:\Data\workspaces --&gt; C:\Users\****\Documents\workspaces Navigate to C:\Data\Workspaces in explorer Click and drag the the path from the address bar onto "Quick Access" in the navigation pane.   Expected Result:   Clicking on the shortcut takes you to C:\Data\workspaces   Actual Result:   Clicking on the shortcut takes you to C:\Users\****\Documents\workspaces   How do you make it so that the shortcut points to the correct path. (the SymLink)  Command Used to create the SymLink:  mklink /D C:\Data\workspaces C:\Users\****\Documents\workspaces   Updated with pictures:  Please note the workspaces symlink inside C:\Data:    When I double-click on the symlink it works correctly. (note the address bar.    When i pin it to the Quick access bar, however, it uses the address that the symlink points to and NOT the symlink address. I've just installed ubuntu server 17.10. During installation, it suggested me to connect to the network through wifi, and so i did. After installation was finished and system was rebooted, computer connected to the wifi automatically (which means, it saved the connection creds somewhere). But in /etc/network/interfaces i found nothing. I need my computer connect to wifi network with static ip, so I've put configuration into the /etc/network/interfaces:  # /etc/network/interfaces -- configuration file for ifup(8), ifdown(8) # Generated by debian-installer.  # The loopback interface auto lo iface lo inet loopback   iface wlp2s0b1 inet static         wpa-driver wext         address 192.168.0.12         netmask 255.255.255.0         gateway 192.168.0.1         wpa-ssid *****         wpa-psk **********         dns-nameservers 8.8.8.8 192.168.0.1 auto wlp2s0b1   When system starts, it doesn't connect using my configuration. It does only after  sudo ifdown wlp2s0b1 &amp;&amp; sudo ifup -v wlp2s0b1  and after this command, system getting a SECOND IP! Server is still available by the ip it gets from DHCP, and in the same time, it is available by the static ip! How to install Google Chrome