Friends' friends If I'm friends with Alice, and Alice is friends with Bob, is there a specific term for my relationship with Bob, or is it just "a friend of a friend"?
Is there a single word for a "friend of a friend"? I am looking for a word that I could use instead of "friend of a friend". On certain occasions, it happens that you may want to talk about a friend of a friend with someone else.   In such cases how would you refer to this friend?
Commutator subgroup and cyclic normal subgroup Can I use multiple regression when I have mixed categorical and continuous predictors? It looks like you can use coding for one categorical variable, but I have two categorical and one continuous predictor variable. Can i use multiple regression for this in SPSS and if so how? thanks! Given $a,b,c$ are the sides of a triangle. Prove that $\frac{a}{b+c}+\frac{b}{c+a}+\frac{c}{a+b}<2$ Are there 'stack' sites for Mac or Windows? There is Ubuntu and Unix/Linux site but is there special 'stack' site for Mac and Windows?  For context, the question I am looking to ask: I accidentally connected a Windows NTFS formatted HDD to a Mac. And the Mac (may be) quick-formatted it. I think that the information is there, but the FAT table is gone. How I can recover the information. Can I use HMAC-SHA1 in counter mode to make a stream cipher? Say I have an embedded device which is only capable of doing HMAC-SHA1 transformations (that device is, in fact, a YubiKey).  Would it be secure to feed it like a block cipher in counter mode to get a random pad suitable as an stream cipher?  Of course, I'm talking about not repeating the counter value ever to encrypt data (so this construction would also need some random IV or treating the counter value as a nonce forever). Calculating grid convergence (True North to Grid North) I would like to know how to calculate the grid convergence angle between True North and Grid North for UTM maps. I am using ArcGIS 10.0 (ArcView licence). and have used the  tool from the Cartography toolbox. However, I would like to know how to calculate this angle myself (using Excel) to compare against the ArcGIS result? Two Circles and Tangents from Their Centers Problem Let $\Gamma_1$ and $\Gamma_2$ be two non overlapping circles with centers $O_1$ and $O_2$ respectively. From $O_1$, draw the two tangents to $\Gamma_2$ and let them intersect $\Gamma_1$ at points $A$ and $B$. Similarly, from $O_2$, draw the two tangents to $\Gamma_1$ and let them intersect $\Gamma_2$ at points $C$ and $D$.  Prove that $AB=CD$.  I've done some extensive angle chasing on this but have been unable to make any real progress. Can't decide whether $ABCD$ is supposed to be rectangle (as in my diagrams), a parallelogram or even a trapezium. There is a homothety taking one circle to the other but as far as I can see this doesn't help as we don't have a clearly defined center to this.  Any help/hints would be greatly appreciated. With ksh I'm using read as a convenient way to separate values: $ echo 1 2 3 4 5 | read a b dump $ echo $b $a  2 1 $  But it fails in Bash: $ echo 1 2 3 4 5 | read a b dump $ echo $b $a     $  I didn't find a reason in the man page why it fails, any idea? Visiting the US after overstaying as a minor 13 years ago? How do I redirect to another webpage? Minimum value of $ f(x,y,z)=\left(x+\frac{1}{y}\right)^2+\left(y+\frac{1}{z}\right)^2+\left(z+\frac{1}{x}\right)^2. $ If $x&gt;0$, $y&gt;0$, $z&gt;0$ and $x+y+z=6$ then find the minimum value of    $$ f(x,y,z)=\left(x+\frac{1}{y}\right)^2+\left(y+\frac{1}{z}\right)^2+\left(z+\frac{1}{x}\right)^2. $$   Thanks in advance. Compute $ \lim\limits_{n \to \infty }\sin \sin \dots\sin n$ Let $m$ be a natural number. Define $f(m) = m + \lfloor\sqrt{m}\rfloor$. Prove that at least one of the number among $m, f(m), f^2(m), \ldots$ is a perfect square. Here $f^k(m)$ denotes the composition of $f$ over itself $k$ times.  I tried the question, but the greatest integer along with square root is creating trouble. When to use a preceding slash in path names? (e.g. for the 'cd' command) I am a novice user and I am trying to install Oracle Java. The process calls for me to access /usr/local/java, but here is the problem. I get as far as /usr/local, then this is the message I get:  leonard@leonard-MT6452:/usr/local$ dir bin  etc  games  include  java  lib  man  sbin  share  src  leonard@leonard-MT6452:/usr/local$ cd /java/ bash: cd: /java/: No such file or directory  leonard@leonard-MT6452:/usr/local$ rm -r ~/java rm: cannot remove ‘/home/leonard/java’: No such file or directory   Help? Whenever I try to get somebody to follow me in Skyrim they something in the lives with "You already have a follower.". The problem is, I don't.   I have not, to my recollection, had a follower at any given point in the game.  The only thing I can think of is that I have (spoiler)      finished Anriel's Endeavors and gotten him as a summon creature.    Or do I have a hidden follower that I can't remember. A dog or a horse perhaps? Note that I do not have a dog or horse following me now. I talked to dog once, and had a horse that died.  Is this a common/known issue? Is there a work around?  Any tips? Reset or remove the BIOS password on my laptop What is meant by a shell is in "vi" mode or "emacs" mode? This question follows directly from . In this case I am specifically unable to understand the part which says:     In that regard, its behaviour is closer to emacs' than with   bash(readline)/ksh/zsh emacs mode, but departs from the terminal   driver embedded line editor (in canonical mode), where Ctrl-W deletes   the previous word (werase, also in vi).   Here we are talking about shells and not editors which are two completely different programs. What does it mean to say shell is in some editor mode?  P.S: You can base your answer on the premise that I understand what a shell is and how to use vim for basic editing. I really hope someone will take a quick look at the following, I would just love to better understand it...  This exercise is from Arnold's "Mathematical Methods of Classical Mechanics", p. 97 in the chapter on d'Alemberts principle:  A rod of weight P, tilted at an angle of 60° to the plane of a table, begins to fall with initial velocity zero. Find the constraint force of the table at the initial moment, considering the table as  (a) absolutely smooth  (b) absolutely rough  (In the first case, the holonomic constraint holds the end of the rod on the plane of the table, and in the second case, at a given point.)"      I must admit, I am pretty unsure on how to do calculations using this "fancy" mathematical kind of physics.  First off, I'm lost with (a). But I'll have a go at (b): As far as I understood, d'Alemberts principle states, that if $M$ is a constraining manifold, $x(q)$ is a curve in $M$ and $\xi$ is a vector perpendicular to $T_xM$, then $x$ satisfies Lagrange's equations  $\frac{d}{dt} \frac{\partial L}{\partial \dot q} = \frac{\partial L}{\partial q} \qquad L = \frac{{\dot x}^2}{2} - U(x)$  iff for the following inner product, we have  $\left(m \ddot x + \frac{\partial U}{\partial x}, \xi \right) = 0$  I guess that's about right so far? The constraint would in this case essentially be $\mathbb S^1$, since the rod moves on a circe around the point in contact with the table. Can we assume that all the rod's mass is at the center of mass?  Would we then have $U(x) = -gx_2$ in this case (where $x_2$ is the vertical component of $x$)?  If yes, then $\partial U / \partial x = -ge_2$. Where $e_1, e_2$ are the horizontal and vertical unit vectors, respectively.  At the inital moment, we have $x = \cos(60°) e_1 + \sin(60°) e_2$, so by d'Alembert's principle we must have  $\left(m \ddot x + \frac{\partial U}{\partial x}, \cos(60°) e_1 + \sin(60°) e_2 \right) = 0$  or written differently  $m \ddot {x_1} \cos(60°) + m \ddot{x_2} \sin(60°) - \sin(60°)g = 0$    So: Is this correct so far? Or am I way off? Is (a) handled any differently up to this point?  Thanks for reading (and hopefully thanks for your helpful reply)!  If anyone could recommend a good problem book (with solutions), in which this kind of mathematical approach is used (I don't know if this is how physicists would actually compute stuff??), I would greatly appreciate it.  Kind regards,  Sam Which day does "next Tuesday" refer to? At what point does next Tuesday mean      the next Tuesday that will come to pass     and no longer      the Tuesday after the Tuesday that will come to pass?   And, when does the meaning switch back? Should I do anything when I see several references that are not used in the text? In a linguistics paper I read, I noticed that several references in the bibliography are not actually used in the text. This is for about 10-15% of the references the case. Should I do anything with this? I always thought that all references must be used in the text, because even if they are just suggestions for further reading you would want some explanation why it is relevant and what you can find where.   I only know the author through their work and do not know the editors. The paper is from 2011. The references are rather general. They are relevant to the paper, but you would want page numbers with them unless you are familiar with them. They are all from different authors and different institutes. It is likely that the references were used in previous versions of the text.