A command for making a string of characters How can I make a command (or is there an existing one?) which takes two arguments: 1) character type 2) N (count) and puts N number of characters side by side?  \newcommand{\foo}[2] {     % sample: \foo{c}{3} -&gt; ccc }
Repeat command n times? Is it possible to define a command, which repeats the following command n-times? Call it for example \Repeat, then   \Repeat[4] \command{...}    should be equivalent to   \command{...} \command{...} \command{...} \command{...}
"media change: please insert the disc labeled" when trying to install Ruby on Rails If a mass moves close to the speed of light, does it turn into a black hole? How to reinstall many removed packages at once? I used sudo apt-get remove python command and accidently removed a bunch of packages that were required. I logged in via command line and installed ubuntu-desktop again but there are other packages that are missing, and I'm looking for a way to easily reinstall those removed packages. Since there's the log at software-center I wanted to ask what the easiest way might be to roll back changes or extract the removed packages list from the software center...  note: I typed sudo apt-get install .... .... ... ... for about two dozen of those removed programs in that list, but when I pressed enter it didn't install any of them because some package names couldn't be found.  The programs were removed at the same date. Why is 248x248 the maximum bi dimensional array size I can declare? When I open the game, the screen stays at the Mojang sign and then crashes. It has something to do with my texture pack, but I can't start the game to change it and it won't let me delete the texture pack folder alone.  I've already deleted the bin and resources folders in the minecraft folder and downloaded the game again. I opened it but the same problem was still there.  How do I properly perform a clean uninstall of the game? Resize image in Python without losing EXIF data I need to resize jpg images with Python without losing the original image's EXIF data (metadata about date taken, camera model etc.). All google searches about python and images point to the PIL library which I'm currently using, but doesn't seem to be able to retain the metadata. The code I have so far (using PIL) is this:  img = Image.open('foo.jpg') width,height = 800,600 if img.size[0] &lt; img.size[1]:     width,height = height,width  resized_img = img.resize((width, height), Image.ANTIALIAS) # best down-sizing filter resized_img.save('foo-resized.jpg')   Any ideas? Or other libraries that I could be using? In cricket, in UDRS screen, if the ball hits the wicket, then why is not out still given? In cricket, in UDRS screen, if the ball hits the wicket, then why is not out still given?  I saw this situation so many times happened; bowler appealed for UDRS for LBW, in UDRS it shows ball hits the wicket, but still not out is given sometimes. I have a shapefile and I want to change the order of the features. Is that possible? I want to sort the features in the shapefile because I'm embedding this shapefile in a mobile app. The app will display a list of features, and although I could do the sorting at load time, I'd prefer to have them sorted. Let $G$ be a non-empty finite set with an associative binary operation so that cancellation law holds, i.e. $ab=ac$ or $ba=ca$ implies $b=c$, for any choices of $a,b,c$ in $G$. Assume that there is an identity element $e$ in $G$. Show that $G$ is a group.  Proof: To show $G$ is a group, conditions must hold. Suppose that $ab=ac$, then $b=eb=(a^{-1}a)b =a^{-1}(ab)=a^{-1}(ac) =(a^{-1}a)c=ec=c$. So left cancellation holds in $G$.  2) Suppose $ba=ca$, then $b=be=b(aa^{-1}) =(ba)a^{-1}=(ca)a^{-1} =c(aa^{-1})=ce=c$. So right cancellation holds in $G$.  3) If $a$ exists in $G$ then $aa^{-1}=a^{-1}a=e$, where $a$ is an inverse of $a^{-1}$. Since inverses are unique, $(a^{-1})^{-1}=a$.  4) Let $x$ be the inverse of $ab$. Then $(ab)x=e$. By associativity we have $a(bx)=aa^{-1}$. Through left cancellation we have  $bx=a^{-1}bx=ea^{-1}=b(b^{-1}a^{-1})$ and $x=b^{-1}a^{-1}$.  Thus $(ab)^{-1}=b^{-1}a^{-1}$. So all conditions hold, $G$ is a group.  Is this proof correct? I know to show $G$ is a group these conditions have to be met. This is all I have to show right? How do I go about porting Ubuntu Touch to different devices? I would like to port Ubuntu Touch to a device that is currently not supported. What are the requirements for doing this and where do I begin? How can I count the number of records that have a unique value in a particular field in ROR? What is this Windows 8 icon for as rectangle icon in the title bar? Is QImage able to open and render pure 16-bit images? Prove $n!>2^n$ for $n\geq4$ using induction. I just want to know if my proof to this question is correct. First, I proved it was true for $n = 4$. $$4!&gt;2^4$$ $$24&gt;16$$ Then, I assumed that it was true for $n=k$. $$k!&gt;2^k$$ Afterwards, I tried to prove it for $n=k+1$. $$(k+1)!&gt;2^{k+1}$$ $$(k+1)k!&gt;(2)(2^k)$$ Since $k!&gt;2^k$, am I allowed to simply do $$(k+1)(2^k)&gt;(2)(2^k)$$ $$(k+1)&gt;2$$ and this is true for all $k\geq3$. Would the last two steps be illegal because I only assumed that $k!&gt;2^k$ is true? Where can we find frequently updated details about travel/entry restrictions due to Coronavirus (nCoV-19)? Due to the outbreak of nCoV-19 (Novel Coronavirus) many Countries have imposed several entry restrictions. But these are quite confusing for a lot of people. Some countries allow transit through parts of China (like Shanghai) but some restrict transit even through Hong Kong/Macau. Philippines restricted passengers coming from Taiwan too, but I think that that was later changed.  Where can one find a list of such restrictions for all the countries, ideally a source that is updated frequently Have Google index different languages at the same URL instead of just the default (English) I have a multilingual PHP site. I have set English as the default language.  The language changes automatically according to the browser settings. If it is French, the site will be seen in French.  However in the Google search results, even if I have the browser in French, the English language appears in the results. How can I fix that?  To be clear I don't want to use subdomains or URLs like www.example.com/fr/. I would like it to work like Facebook. In other words, can I do something like  for() {     for {        for {        }     } }   Except N times? In other words, when the method creating the loops is called, it is given some parameter N, and the method would then create N of these loops nested one in another?  Of course, the idea is that there should be an "easy" or "the usual" way of doing it. I already have an idea for a very complicated one. How to buy plane tickets for job interviews? I am currently on the academic job market, and scheduling on-campus interviews with institutions that might want to hire me.  Suppose I am invited to an on-campus interview at the University of X, and must travel there by air.  They handle travel on a reimbursement basis: I buy the plane ticket, and then they reimburse me.  However, the interview is a few weeks away.  Since the job market sometimes moves fast, there is a chance that by the time of the scheduled interview, I may have already accepted another offer (say from the University of Y).  Of course I should then decline the interview at X, but I would have already bought the plane ticket.  How should I plan for this contingency?   I could buy a refundable ticket to X.  However, these are normally several times the price of a non-refundable ticket, and if I do end up traveling to X, they might balk at reimbursing me for such an expensive fare. I could buy a non-refundable ticket to X.  If I end up not going there, I could ask X to reimburse me for the cost of the ticket (or at least the "change fee" charged by the airline to let me use the ticket's value for a future flight).  However, I suspect they will be reluctant to reimburse me for a trip I'm not making, and might refuse to do so altogether, in which case I am out-of-pocket. I could wait until the last minute to buy a non-refundable ticket for X.  But it may still be expensive for them (or may exceed their limits), and the most convenient flights may be sold out. I could contact University of X and ask them for guidance.  I'm a bit hesitant to do this, as I am afraid that if I bring up the possibility that I might accept another position, they might think I am not seriously interested in theirs.   Is there a standard way to handle this situation?  This is in the United States, if it matters. Are  and the  really the same thing?  Not too long ago, Susskind and Bousso uploaded the article "" with the thesis that the many-worlds interpretation and the multiverse of eternal inflation are one and the same thing. The parallel worlds of one are exactly the same thing as the parallel worlds of the other.   First, they claim decoherence can't happen over a complete description of the future light-cone of the measurement. Then, they apply that principle to eternal inflation. Without decoherence, superpositions of nucleating bubbles and metastable vacua can't decohere. According to the anthropic principle, most bubbles have no conscious observers, but an exponentially small minority do. Apply black hole complementarity to causal horizons.  Then, somehow, in a way I can't follow, they combine causal diamond worlds into a global multiverse.  Then they claim decoherence is reversible.  My head is spinning. What are your opinions on this paper? Are (un)tapped permanents still legal targets for "(un)tap target permanent" effects? So I noticed that many cards with tap-effects ship with a clause specifying that they can only be used on untapped permanents, such as  and .  So here's my question:   Doesn't that imply that, given the right situation, one can legally tap an already tapped permanent?   I'll give an example of the kinda scenarios this is relevant for: Can  activate her first ability when no untapped cards are around? Or, thinking untap-effects, could I bounce a forest with  even when there isn't a tapped creature available?  Notice that, unlike the previous batch of examples, the wording on these lacks the clause restricting their use to un/tapped permanents - does that mean that they aren't?  Any kind of clarification would be greatly appreciated here.