How to add one attribute column to another with a space between the two in QGIS
Concatenating string with space
Give a one-to-one and onto function from $\mathbb{N} \times \mathbb{N}$ to $\mathbb{N}$ When should one use "should" and when should one use "must"? I tend to use should when it's a suggestion I don't have a strong opinion on, i.e. it could be done in many other ways than the one I'm suggesting and it can still happen.     You should stop by that gas station to go to the bathroom.   On the other hand, I usually use must for things that have to happen in a certain way; any other way would make that thing not to happen. The problem is that some people find this usage harsh, as they receive it like if I'm giving them an order.      You must cross the street to get to that store.   To me, it's just a depiction of reality, not an order. But I'm neither a native speaker nor a regular person. :-)  So, what's the proper use for must and should? Does this use differ among the English dialects? Lyircs of Free by Natalia Kills:     I'm free      I just spent all my money       but I rocked that like it don't cost a thing   Shouldn't it be "I've just spent all my money"? As far as I remember, our English told us to use Present Prefect in such case because of the just. Since I can't find any alternative to Linux'  elevation command, I have the following question:  How to define a PowerShell function which requires elevation? I mean UAC prompt.  Say, such function follows:  function system-check {     SFC /ScanNow }   System:  Windows 8.1 Pro 64-bit  PowerShell:   Major  Minor  Build  Revision -----  -----  -----  -------- 5      0      10586  117    EDIT1:  To be 100% understandable let me rephrase:   I run PowerShell as user I run the aforementioned function system-check I want the function to elevate in order to be able to execute the command; note, that I want the UAC prompt to appear Why do people buy stocks that pay no dividend? Before recently, Apple Inc. did not give dividend to shareholders.  This makes me curious why people buy Apple Inc. stocks; while it might be due to the expectation of selling stocks at a higher price, this can only be possible if other people are thinking the same, thereby increasing demand. But the stocks themselves do not pay interests - so Apple's amazing revenue/profit records would not matter.... How can I add an empty directory to a Git repository? How can I add an empty directory (that contains no files) to a Git repository? Passing an enum value as command parameter from XAML I want to pass an enum value as command parameter in WPF, using something like this:  &lt;Button      x:Name="uxSearchButton"      Command="{Binding Path=SearchMembersCommand}"      CommandParameter="SearchPageType.First"     Content="Search"&gt; &lt;/Button&gt;   SearchPageType is an enum and this is to know from which button search command is invoked.  Is this possible in WPF, or how can you pass an enum value as command parameter? Stack Overflow, Stack Exchange, Area 51: What's the difference in a nutshell? Stack Overflow, Stack Exchange, Area 51: What's the difference in a nutshell? I've read the faq's and they all seem to be the same to me - Just Q &amp; A on a variety of topics.  What's the difference in a nutshell? If I have a software engineering question, which site is best for me to use? I keep hearing a lot about functors in C++. Can someone give me an overview as to what they are and in what cases they would be useful? I have a PC with an OEM install of Win 8 updated to 8.1.  It has 3 physical hard drives in it.  The drive where Windows is installed has a LOT of partitions on it already.    Can I install Ubuntu on a different physical hard drive than Windows, and be able to dual-boot?  I am able to boot to a live USB of Ubuntu 14.04, so I think I'm about ready to proceed.  But if I can make my installation easier by using a different physical drive, I'd like to do that. Injection from $\mathbb{N}\to\{0,1\}$ to the set of all monotonic decreasing functions from $\mathbb{N}\to\mathbb{Z}$ this is a follow up to the problem described .  I have the same problem and the proposed solution does not completely solve the problem. I mean, it does solve the problem but also creates another one. The new problem is that the theorems, lemmas and the rest are placed in such as way that they are not cut (of course), but this leaves then big empty spaces in many pages. So the problem is that, the problem described  does not seem to be fully resolved using the nocut option.   Do you any of you have a good idea on how to solve this?  Thanks! I assume that the following sentences are grammatically correct:   He resents your being more popular than he is. Most of the members paid their dues without my asking them. They objected to the youngest girl's being given the command position. What do you think about his buying such an expensive car? We were all sorry about Jane's losing her parents like that.   I'm still getting used to this possessive gerund structure. It sounded so weird to me at first. Is the structure used in both formal and informal contexts? Are there any alternative structures that result in the same meaning and are more frequently used? (Examples taken from ) + or @ mark after running 'ls -al' In Mac OS X, run 'ls -al' gives me something like this.   drwxrwxrwx+  4 smcho  staff     136 May  5 09:18 Public drwxr-xr-x+  6 smcho  staff     204 Feb  1  2010 Sites drwxrwxrwx   9 smcho  staff     306 Feb  2  2010 backup drwxr-xr-x@ 36 smcho  staff    1224 Sep  4 22:51 bin    What's the + or @ at the end of the first column means? Is this unique to Mac, or common in UNIX?   ADDED  After Michael Mrozek's answer, I ran 'ls -ale' to get the following.   drwx------+ 66 smcho  staff    2244 Aug 30 13:40 Library  0: group:com.apple.sharepoint.group.3 allow search  1: group:everyone deny delete drwxr-xr-x   3 smcho  staff     102 Sep  4 15:01 Mail drwx------+ 13 smcho  staff     442 Aug 28 17:55 Movies  0: group:everyone deny delete drwx------+  6 smcho  staff     204 Jul  9 09:37 Music  0: group:everyone deny delete drwx------+ 11 smcho  staff     374 Aug 28 16:55 Pictures  0: group:everyone deny delete drwxr-xr-x   3 smcho  staff     102 Mar 18 15:43 Projects drwxrwxrwx+  4 smcho  staff     136 May  5 09:18 Public  0: group:everyone deny delete drwxr-xr-x+  6 smcho  staff     204 Feb  1  2010 Sites  0: group:everyone deny delete   What those appended messages mean? Why do I have them for some of the files? I don't remember doing anything particular for them. Accidentally created directory named "~" (tilde) I managed to make a directory literally named ~.  (Apparently, Python's os.mkdir('~/something') does this.)  How do I remove it without nuking my home?  Also, if it helps, I have my real /home on a separate partition. And the duplicate ~ is located in (the real ) ~. Considering the irreducible (by condition) polynomial $f=X^4-2aX^2+b\in\mathbb Q[X]$ and the field extension $K=\mathbb Q(\sqrt{a^2-b})$ of $\mathbb Q$, I want to show the following result:    For $[L:\mathbb Q]=4$ we have $\sqrt b\in K$ where $L$ is the splitting field of $f$.   My thoughts so far: The four roots of $f$ are $\pm\sqrt{a\pm\sqrt{a^2-b}}$. If $L$ is of degree $4$ it must be primitive since $f$ is irreducible, so $L=\mathbb Q\left(\sqrt{a+\sqrt{a^2-b}}\right)$. Then, by multiplying the two roots $\sqrt{a+\sqrt{a^{2}-b}}\cdot\sqrt{a-\sqrt{a^{2}-b}}=\sqrt{b}$ we have that $\sqrt{b}\in L$. Now I want to look at $$\mathbb Q\subset K\subset K(\sqrt b)\subset L$$ and differentiate some cases. The case where $[L:K]=1$ is trivial and the case $[L:K]=4$ can't happen because if we square any root and subtract $a$, we get $\pm\sqrt{a^2-b}\in K$ which means $[L:K]\leq 2$. So let's look at the case where $[L:K]=2$. As I see it, we get two subcases:   For $[L:K(\sqrt b)]=2$ we have $K(\sqrt b)=K$ which finishes the proof. For $[L:K(\sqrt b)]=1$ we have $K(\sqrt b)=L$. This means that $L$ is also the splitting field of $(x^2-b)(x^2-(a^2-b))$. Is this a contradiction? How do I finish this case? I remember reading this book in the late 80's or early 90's. It was a - sort of - semi SciFi contemporary fairy tale.  It was set in Manhattan in contemporary times, near future and (I think) late 1800's. There was a mist wall round New York that ships could disappear into and arrive out at different times.  There was a man with a white horse, the horse could fly but had forgotten how. The man is brought forward from the past but (like the horse) forgets who he is.  An engineer arrives from the future in a gigantic ocean liner and builds a bridge of light to heaven (possibly at the last millennium turn over).   It was a very involved book with a huge cast of characters that all had some part to play in the story.  In the 1800's story there was a girl suffering from consumption, she slept in a glass room on the roof of her house, open to the freezing winter air, it was what kept her alive. She was rich (the family had made money in whaling) but somehow she and The Man (the guy with the white horse, who was pretty much a nobody) met and fell in love (I think).  Some of the story was set around a lake in upstate NY, and one character started off in San Francisco (contemporary times) and traveled to the lake.  Anyone any idea what I'm talking about? Is there a way to disable the hardware on/off switch for the Wireless interface? Problems with \pgfplotstableread and relative paths I'm buying a bus ticket to get to Boston 23 hours before my flight to ensure I reach my departure airport on time.  If I didn't arrange bus transport well in advance, what legal remedies would I have if a delayed bus caused me to miss my flight?