For the following code:  const int &amp;Rtest = 0;   I'm unsure why g++ accepts this (would all compilers accept this?). I thought that reference types must reference objects, not arbitrary numbers, so what is Rtest at this point? How is it used in programming?  In contrast:  int &amp;Rtest = 0;   Will not compile, and this makes sense to me, because reference types must reference objects.  So why does making the type reference const int&amp; make it acceptable?  (I know int does not matter, this is just the type I happened to use.)
In some text it is given that we can't assign constant values to a reference variable. When I executed such a program I could do it. Is there any condition we can't assign a constant value to a reference variable?
Why don't electrons crash into the nuclei they "orbit"? What is the maximum number of people that will join a settlement? I've got two settlements on the go that I'm paying attention to - Sanctuary and the Starlight Drive In. Both of these settlements have radio towers and beds and all resources in the green however they appear to have stopped growing at 10 people in each settlement even though happiness is above 80 and I've got 15+ beds at each location.  What is the maximum number of people that will join a settlement? How is "I have come" + infinitive different from Present Perfect? Is there a general formula for finding all subgroups of dihedral groups? What happens if my ESTA expires on the day of arrival? Had it not been vs If it were not for I've just seen the following sentence on a band's biography:     Had it not been for a studio theft, the band might never have made that song.   Then I was wondering if I can change this sentence to:     If it were not for a studio theft, the band might never have made that song.   Is the second sentence correct? Are they interchangeable?   Thanks in advance. Computing $ \lim_{n\rightarrow \infty}\left(\frac{1^n+2^n+\cdots \cdots +n^n}{n^n}\right)$ One-dimensional [Noetherian] UFD is a PID How to save an alias of an eval $(other_comand) command I've been using docker for a while and there's a command I write each time I boot up my docker:  eval $(docker-machine env)   I know eval shouldn't be used unless necessary, but it's mentioned by the following:  docker-machine env outputs environment variables like this:  docker-machine env export DOCKER_TLS_VERIFY="1" export DOCKER_HOST="tcp://&lt;some_ip&gt;:&lt;some_port&gt;" export DOCKER_CERT_PATH="/home/gableroux/.docker/machine/machines/default" export DOCKER_MACHINE_NAME="default" # Run this command to configure your shell:  # eval $(docker-machine env)   eval grabs these and load them in my current session.  Now what if I'd like to have an alias like this:  alias dockereval="eval $(docker-machine env)"   Syntax is good, but the problem is when a dotfile (let's say .zshrc as an example), well the content of the $() is evaluated when registering the alias when you source that file.  which dockereval   Results in  dockerenv: aliased to eval   I tried a few things like:  alias dockereval="docker-machine env | eval" alias dockereval="docker-machine env | /bin/bash" alias dockereval="eval `docker-machine env`"   but none did work. 2nd one is probably because it's running in a different session, 3rd does the same as $() I guess  Is there an other way to load these environment variables with an alias? Put   $$ l^{\infty} = \{ (x_n) \subseteq \mathbb{C} : \forall j \; \;\ \;|x_j| \leq C(x)\} $$  I want to show that $c_0$, the space of all sequences of scalars that converges to $0$ is closed subspace of $l^{\infty}$.  MY atttemt: Take arbitrary sequence $(x_n) \in c_0$. We know $x_n \to 0$. but $0 \in c_0$. Therefore, every sequence in $c_0$ converges to an element in $c_0$. Hence, $c_0$ must be closed  Is this correct? thanks I've found a nasty VBS way to do this, but I'm looking for a native PoSh procedure to edit the properties of a .LNK file.  The goal is to reach out to remote machines, duplicate an existing shortcut with most of the correct properties, and edit a couple of them.  If it would just be easier to write a new shortcut file, that would work too. Mac equivalent of Ctrl + Space to select an item on a list I want to select non-consecutive items on a list, without using a mouse/trackpad - there should be no clicks involved.  In Windows and Linux (at least Ubuntu) an item can be selected using Space/ button, which, in combination with arrows and Ctrl key allows me to select multiple items in any environment (file manager, IDE etc.) - e.g.  Enter a directory -> hold Ctrl -> down arrow twice -> press Space -> down arrow twice -> press Space.  Now I should have items 1, 3 and 5 selected. Is there a way to do the same thing in OS X?  PS. Sorry for such a verbose description, but so far every answer I encountered advices using Command + Click, and this is something I don't want to do. Sum of a power series $n x^n$ How do I decrease the size of the page file? I just upgraded my laptop RAM to 12GB (W510, 4 DIMM slots), and since I am using a SSD, I find hard drive space to be quite precious. However, since I have more than enough RAM for most stuff, I think I can get by with probably around 4GB of page file. however, on C drive, there is a pagefile.sys which I assume to be reserving space for page files in the OS, how would I decrease the size of this file? I've been using gksudo nautilus and sudo nautilus through Alt+F2.   What's the difference? They look very similar! Origin of electric charge Baryons have charges that are the result of a polynomial calculation of their building blocks (quarks)'s fractional charges. But what gives these quarks electric charges? What interactions do they have with photons? And what about leptons, like muons and electrons? How do they get their -1 charge? And then, how do positrons and anti-muons get +1 charge? Same goes for quarks: how does up-antiquarks get -2/3 charge? Or I may want to formulate my question this way:  How does any elementary particle interact with the EM-Force to get an electric charge? Schengen visa validity start date My Chinese in-laws intend to visit us in one month from now. Their visa is valid from Nov 23rd. Would it be possible for them to take the airplane on November 22nd in China and arrive in Schengen area on November 23rd?  Or does the visa already have to be valid upon departure?  In our particular case, they still need to transfer in Beijing first. The actual flight to Schengen zone effectively only departs on the 23rd so I guess that should be completely fine then? What is least angle regression? Conceptually, I don't understand what least angle regression Least Angle Regression (LARS) is and why it solves LASSO ().  We know that LASSO is:   $$\arg \min_x {\left\| A x - y \right\|}_{2}^{2} + \lambda {\left\| x \right\|}_{1}$$  From my understanding LARS is exactly like line search from CGD, where you take the variable that gives you the most desire result and iterate through.  Can someone give a walk through on how LARS solves LASSO? By accident, I recently removed some videos from my phone. I tried to restoring them with Recuva and TuneUp Utilities and the results were "undf" files.  I tried to open with VLC, Media Player Classic and other video players to no avail. Where/how do I find out the codec for these files?   I would really love to be able to watch these videos again. Presentation $\langle x,y,z\mid xyx^{-1}y^{-2},yzy^{-1}z^{-2},zxz^{-1}x^{-2}\rangle$ of group equal to trivial group