Pentation Notation - How does it work?
How exactly does Knuth's Up-Arrow notation work?
math fallacy problem: $-1= (-1)^3 = (-1)^{6/2} = \sqrt{(-1)^6}= 1$? When $d$ is in $\mathbb{Z}$, $\mathbb{Z}[\sqrt{d}] = \{a_0 + a_1 \sqrt{d} \mid a_0, a_1 \in \mathbb{Z}\}$  However, when $d$ is in $\mathbb{Q} \setminus \mathbb{Z}$, I cannot prove it.  Of course, when I see an example, I can understand that this is not a finitely generated abelian group, but I want to know the proof in general. Where should I start with Star Trek? (TV series only, not the movies) I haven't seen any of the stuff in the Star Trek franchise, except for one of the movies, and now I want to remedy the situation. I am not interested in the movies, just the TV series. However, since the show has many seasons, I am not interested in watching the show start to finish. So, where (i.e what series/season) should I start with? Do I really need to see the series in real-world chronological order?   Note: I am somewhat familiar with Star Trek, that is I know the basic premise - ships in space, with war between different space-faring sentient species. Difference between 'max distance' and 'radius' in Physics.SphereCastAll HTTP and HTTPS impacts on SEO I have a website http://www.domain_1.com/ hosted in a shared webserver.  I have used SSL for another website https://www.domain_2.com/ on the same server.  Due to some technical limitations (single IP), if you try https://www.domain_1.com, browser will show the same domain_2 website. But this is not a concern for me.  Question: will this scnario impact SEO of domain_1 (non-HTTPS) site? How to remove app which is greyed out, can't be deleted, won't open and doesn't appear in apps list? I have this app with a greyed out icon which I'm trying to delete.    I tap and hold, and it asks me if I want to delete it and its data. I confirm and nothing happens.  I try to open it and nothing happens.  I go to Settings>General>Usage and it's not in the list.  I reboot the device and it's still here.  Is there another way to force deletion of this (ghost) app? Do the SO admins have any plans to release the underlying code for SO at all? I appreciate that the code may be part of their competitive advantage, but it strikes me that the underlying system would work for any topic, not just programming.  I am not advocating this, just curious really, but figured it might be under consideration as most of the value in SO is in the questions and answers, which have been released under a relatively open CC license. Consider this example from the Rogue class traits:     Trained Skills: Stealth and Thievery. From the class skills list below, choose four more trained skills at 1st level.   &nbsp;&nbsp;&nbsp;&nbsp;Class Skills: Acrobatics (Dex), Athletics (Str), Bluff (Cha), Dungeoneering (Wis), Insight (Wis), Intimidate (Cha), Perception (Wis), Stealth (Dex), Streetwise (Cha), Thievery (Dex)   The Rogue is trained in Stealth and Thievery. However, they're also included in the Class Skills section, and it invites you to: 'choose four more trained skills' from that list. This seems to be similar for all the classes.  So can you train Stealth and Thievery as a choice as well have it initially trained or the equivalent for other classes? Deriving of formula for finding the length of median In the below image    $AD$ is the median of $\triangle ABC$  We know that $m_A = \frac 1 2 \sqrt{2b^2 + 2c^2 - a^2} $    But can someone tell me how it's derived !! I am just unable to think of it !!   But I assume it muste be linked with the Appolonius Theorem !! how to execute mongo admin command from java The velocity of the flowing coming out of the balloons? Last day , when i was working on two interconnected balloons , a question was kicking my brains !!! This is the explanation of the question:  First , suppose a system that composed of two spherical membranes filled with air (two balloons have different initial volumes {means that the pressure inside which balloons are different} and the air pressure is 1 a.t.m) . We connect them with hollow tube and a valve. When we open the valve , one of them shrinks and the other one expands (It depends on their pressure) .  So how can we get the velocity of the flowing air between two balloons? (Consider everything but if you have reasons for not considering one of them -for example the ratio of friction in the tube- Don't consider them and just tell me the reason)  Thanks Would fewer Jedi be more powerful? Can we use non-gravatar avatars? I have found a few mods for minecraft I like a lot. I know you cant use them all at the same time. I know that some go together well, so how do I find out what goes with what?  Is there a way to load some for now, and unload them later so that I can change them out? I got a patch device but I don't think it works that well.  I tried to play with this stuff on my own but I got things so messed up that I had to delete everything and start over. So what am I doing wrong?  KH How to remove Apple System Apps How can I delete Apple OS X application such as Photos, iPhoto, and others that I never use? Conversion Error setting value for 'null Converter' - Why do I need a Converter in JSF? Set Text Color for textView Android Can you prove that if $p$ is a prime greater than $5$, then the sum of the squares of the quadratic nonresidues modulo $p$ is divisible by $p$?  Note that I have just proved that the sum of the quadratic residues modulo $p$ is divisible by $p$ for $p$ greater than $3$. How can I copy files from A to B, only including files that exist in B? I'm on Windows 7 Professional, and this is my scenario :  Folder "Asd" (C:\)              Folder "Asd" (D:\) File 1                          File 1  File 2                          File 3  File 3                          File 4 File 4 File 5   I'd like to select the folder on C:\ (without selecting each single file, of course) and copy it over the same folder on D:. Usually, it will copy all files. But what I'm looking for is to copy only files (from C:) that are contained on folder d:.  So in my case I'd like to replace only File 1, File 3 and File 4.  File 2 and File 5 must be ignored.  Is it possible? How do I delete a folder which is nested quite deep and avoid "File name too long"?