Render looks darker than Look Dev mode
What is LookDev/Material Preview mode for in 2.8?
How to show that Klein four-group is a normal subgroup of the alternating group $A_4$ I want to show that the Klein four-group is a normal subgroup of the alternating group $A_4$.   I am using the information in , that shows explicitly $A_4$, and Klein four-group as a subgroup.  I know that there is the direct way, by definition, but is there a way that does not require actually multiplying so many permutations ? How is the electostatic field propagated by the vacuum? How does a charge feel the presence of another charge when there is NOTHING between them? Is the word "vacuum" equal to "nothing"? Imagine two charges of opposite sign, far from one another in vacuum, and moving with constant velocity - s.t. none radiates energy, none emits photons. At some time though, the course of their movement brings them closer. They begin to accelerate toward one another. How do they feel the presence of one another? During their constant movement no photons are emitted, no "information" spreads in the universe about their presence. Does removing an iPhone from my icloud account also erase the data? I lost my iPhone 6S recently. I think it fell off my car and was crushed because it has been offline (according to Find My iPhone) ever since. I want to erase the phone and remove it from my iCloud account since the phone is gone.  However, I can't erase the phone until it comes back online. I do have the option to remove the device from my iCloud account. If I remove the phone from my iCloud account, does that also erase the data? The phone has a password on it, will it continue to be locked in case someone finds it after I have removed it from my iCloud account? How do you run your own code alongside Tkinter's event loop? My little brother is just getting into programming, and for his Science Fair project, he's doing a simulation of a flock of birds in the sky. He's gotten most of his code written, and it works nicely, but the birds need to move every moment.  Tkinter, however, hogs the time for its own event loop, and so his code won't run. Doing root.mainloop() runs, runs, and keeps running, and the only thing it runs is the event handlers.  Is there a way to have his code run alongside the mainloop (without multithreading, it's confusing and this should be kept simple), and if so, what is it?  Right now, he came up with an ugly hack, tying his move() function to &lt;b1-motion&gt;, so that as long as he holds the button down and wiggles the mouse, it works. But there's got to be a better way. Something's been bugging me about SO for a while now, that is the inaccuracy of "length of time" strings.  The best example I can give at the moment is .  If you look at the length of time he's been registered, it says 1 year.  He joined the site September 2008, which is only 3 months off two years.  It's the same with answers - you can give an answer 50 seconds before anyone else, but at certain times page views will show both as "5 minutes ago" or whatever.  That's not quite as bad, but with answers being sorted "randomly by votes" by default you could lose out on votes or being marked as the correct answer to the slower answer even if they're both the same.  There's probably a better method amongst these, IMO:   "Vulgar fraction" unicode characters     Member for 1½ years   answered 5¼ minutes ago asked 3⅓ hours ago  Different units   Member for 21 months (at least it's better than "1 year") Answered 306 seconds ago (ugly, I know) Asked 64 minutes ago (also ugly)  Combining units   Member for 1 year 9 months (fits easily on the profile screen) Answered 5 minutes 6 seconds ago (probably too long) Asked 3 hours 20 minutes ago (also long)  Rounding up   I personally prefer option 1, unicode fraction characters.  "Member for 21 months" is pretty good too because it's easy to quickly work out.  "Asked 452 seconds" ago is horrible though.  EDIT: I'm completely aware of the timestamp hover because I am forced into using it so much. It's a great feature, but it's not really in your face so not everyone knows about it. I still think there's a better "glancing" solution than having to hover over the time string. Why did Obi-Wan allow Leia to get adopted by such a high profile figure? I know that Leia is a princess because she was adopted by the Queen of Alderaan, but why would Obi-Wan allow this? Wasn't the original plan of Obi-Wan and Yoda to hide the Skywalkers from Palpatine? Luke was placed into a very low-profile position, being the child of two farmers on a backwater planet. However, Leia occupies a very important political position.  Is there any reason why Obi-Wan would do this if he was trying to hide her? What is the point of isomorphism concept? If $A^2\succ B^2$, then necessarily $A\succ B$ I remember reading somewhere about the following properties of non-negative definite matrix. But I don't know how to prove it now.  Let $A$ and $B$ be two non-negative definite matrices. If $A^2\succ B^2$, then it necessarily follows that $A\succ B$, but $A\succ B$ doesn't necessarily leads to $A^2\succ B^2$.  How can you prove it? Thanks! How do I allow long URLs to have line breaks at any point. This is in the bibliography not the main text. I am trying to save space so don't want extra spaces to be added to make it only break at slashes, for example, as it does by default.  I am using biblatex+biber. So, as the title read I happened to overstayed my Schengen visa for 6 months does anyone know what the consequences could be. If I wanted to return back to Saudi Arabia. app engine datastore auto-clears every time project runs read only access to all files in a specific sub-folder I have got a specific folder located in "/home/.../reboot/".  I have a series of users that require read-only access to the ever changing files within.  My problem is that the same users are not authorized to view any of the parent directory files.  Right now, the only thing I have in place is that their starting folder is at "/home/.../reboot/" by changing the etc/passwd file; and I need to block all access to other folders.  How could I only give them access to this directory? "Show," "shown," and "showed" root@SERVER ~$ df Filesystem  512-blocks  Free    %Used   Iused   %Iused  Mounted on /dev/YXCV   655360      365632  45% 6322    13% / /dev/ASDF   3801088     670648  83% 41759   32% /usr /dev/ASR    1048576     500496  53% 5555    9%  /var   How can I pipe the df command's output to only display lines that have more usage than 80%?  e.g.: it would only display:  /dev/ASDF   3801088     670648  83% 41759   32% /usr "Timed Out" error when trying to join server Arbitrary products of quasi-coherent sheaves? Examples where $H\ne \mathrm{Aut}(E/E^H)$ Over time, I've noticed an increasing practice among moderators of the smaller sites (i.e. not in the Trilogy) to move extended comment chains to chat, just because they're too long. Is this a good idea? In the past, I've taken the position on many occasions that I believe that comments serve two purposes only: clarification, and asking for clarification.  I take this position because as a mod I want the freedom to purge a comment trail that is clearly running off the rails without having to argue with anyone about politeness definitions. But that's not the same thing as two pedantic C++ language lawyers debating the finer points of &quot;undefined behavior.&quot;  I give wide latitude to such discussions, as long as the participants don't start throwing spears, because I believe they are instructive. The SE software even has accommodations for this.  Long comment chains are automatically collapsed, so as not to disrupt the Q&amp;A format of the post.  And moving a comment chain to chat is not even a move, really; to do an actual move, you have to perform the conversion, and then delete all of the copied comments from the post. Here is a recent example:  and it's accompanying . What I find amusing is that the OP's detailed POV about the term, where he floats a theory about why everyone thinks that &quot;bugged&quot; is not a thing (that conversation took place in the comments, and is now safely sequestered in the chat room) gets to stay prominently featured in his question, at the very top of the post. Now you could argue that the chat room is a better environment to have these discussions anyway, and you'd be right.  I could argue that if we're going to do that, then why not just automatically convert long discussions to chat rooms? The problem is not so much where the comments reside.  I don't understand why mods are taking it on themselves to fix something that isn't hurting the site (at least in my opinion).  In addition, every time I see this happen, the participants in the conversation immediately lose interest in it.  The only comment that was posted in that room after all the comments were moved is most likely this one:  It wouldn't surprise me if the folks using &quot;bugged&quot; to refer to a certain software quality are the same folks who refer to their programs as &quot;codes&quot; and who believe textspeak is the pinnacle of modern English.  Which nobody will ever see. :) Some mods are really aggressive about this.  I discussed this with a mod on Physics, and he told me that they routinely move discussions when they think they might run off the rails. Aside from the repetitive appearance of the black cat, I can't remember seeing any living animals, either inside the Matrix simulation or in Zion.  How come? Is there an in-universe explanation? 'AND' vs '&&' as operator