Why do list comprehensions write to the loop variable, but generators don't?
List comprehension rebinds names even after scope of comprehension. Is this right?
argument about fallacy of diff(M) being a gauge group for general relativity I want to outline a solid argument (or bulletpoints) to show how weak is the idea of diff(M) being the gauge group of general relativity.  basically i have these points that in my view are very solid but i want to understand if there are misconceptions on my part that i'm simply not getting and if its so, i ask for help to make the case more solid, or understanding why it doesn't apply (to gravity):    (thanks to Raymond Streater for making that point completely clear) gauge invariance in electrodynamics is an observation that physical observables are unchanged after a gauge transformation without changing coordinate frame ( we are ask to believe that in gravity someone did the same? that is, someone made the observation that physical observables are unchanged after a diffeomorphism-gauge-transformation, only to later argue that because of this, that there are no physical observables to begin with, that doesn't make a lot of sense, to not say that its just plain stupid circular argument ) . The invariance is of course broken when the theory is quantized and $\hbar$ makes an appearance, because it assumes a preferred scale for certain energies. The key point here is: classical gravity is not special regarding having diff(M) as a symmetry group from bulletpoints 2 and 3, if i cannot infer that Diff(M) is a gauge-invariance of electrodynamics, the same should apply to gravity   For this question, i would say that a valid answer would either disprove any of the arguments as fallacies themselves (hence showing a solid argument why gravity is special and diff(M) is without a doubt its gauge group), or improve the argument for making it bullet-proof (sorry for the pun) Get text between two strings Regex VB.Net Is $f(x)=10$ a periodic function? I am not getting satisficatory explanation for this. Clearly $f(x+T) = f(x)$ for all values of $T$.  If we assume it is periodic, does this mean period =  $0$? footnotes at the end of the book Is it possible to have all footnotes placed at one specific place in my document instead of bottom of each page? I have multiple footnotes scattered in the article and it would be clearer if all of them are at the very end of the article  Edit (moved from an ``answer'')  is it possible in endnotes to have links in each number where I placed footnote to the actual footnote at the end? Include reviews made outside of /review in progress towards the badge The recent changes to /review has gotten everyone interested in cleaning up the muck. At present, only posts "reviewed" (by clicking on the review link) and actions taken (up/down/close/edit/flag) from within /review count towards the badge.   However, it is entirely possible that one catches a poor question outside of /review (e.g., on the front page/tag page, etc.) and "reviews" it and takes some action on it. However, these actions do not count for the badge, at present. In all likelihood, this question would've also been in the /review queue and if one were fortuitous enough to have reviewed it there, these actions would've counted towards the badge.   Would it be possible to include reviews made outside of /review to count if the question was also in the review queue? Note that this shouldn't apply if the question dropped out of the queue (either by inaction or after it was edited and improved by previous reviews). Solution for A/C Condensate Drain Line that doesn't require emptying a bucket of water every day? Schwarz's Lemma, fixed points question This is from an old qualifying examination question.  If f is holomorphic in the unit disk $D$ and $|f(z)|&lt;1$ for all $z\in D$. Suppose also that $f$ has two distinct fixed points in $D$ then $f(z)=z$ for every $z\in D$  I know that I have to use the Schwarz's lemma and may be make use of Möbius transformations. I tried setting $g(z)=\phi_a\circ f\circ \phi_{-a}$. But that does not seem to work because I don't see why $|g(z)|=|z|$ for some non zero $z$.   Any helpful hints are greatly appreciated.  Edit: Of course the $a$ above is one of the fixed points. How to make my own Dropbox / Ubuntu One server at home? Does anybody know of any resources that can show me how to make my own "Dropbox, Ubuntu One" server at home?  I really like the idea of these services, but I don't want to put my 'stuff' in the clouds. Ideally, it should have a client that runs on Linux and Windows.  I tried to setup iFolder on my Ubuntu 10.04, but without any success so far. How many arrangement of the letters in MISSISSIPPI have at least 2 adjacent S's?  I was thinking that I can glue two of the S's together, so there will be 9 letters plus the special letter SS, and the number of arrangements will be $10!/(2!2!4!)$, this is not the correct answer, but what is wrong with my reasoning.  (the correct answer is $11!/(4!4!2!)-7!/(4!2!)\binom{8}{4}$, I understand the solution) Why does Stephen Hawking say black holes don't exist? Problem (1.8): There are ten girls and four boys in Mr. Fat's combinatorics class. In how many ways can these students sit around a circular table such that no boys are next to each other.   My Attempt: Total number of ways in which both boys are girls can be arranged on a circular table is $13!$ and the number of ways in which any two boys can be together is $2!*12!$. Therefore the answer is $13!-2*12!=11*12!$. Is this answer correct? I am asking this because I am confused about the exact meaning of the line "no boys are together." Does this mean that no two/three/four boys are together?   Note: Meanwhile I have made another attempt on the problem. We can place the $10$ girls on the circular table in $9!$ ways. Then we are left with $10$ spots which need to be filled with $4$ boys. This can be done in $P^{10}_4$ ways. Thus, the number of ways is $9!P^{10}_4$. Getting always extra button on display .. 1 button dont have any ID I am having problem while looping.  I am always getting an extra button. Please help.   {this.state.items.map(myitems1 =&gt; {     return (        &lt;div key={myitems1.Id}&gt;            &lt;span&gt;{myitems1.Item_x0020_Name}&lt;/span&gt;            &lt;button onClick={e =&gt; this.dosometing(myitems1.Id)}&gt;Offline&lt;/button&gt;        &lt;/div&gt;     ); })}   I can see the collection has only three (3) values, But I am getting 4 buttons on screen.   Getting always extra What is the difference between linear regression and logistic regression? What is the difference between linear regression and logistic regression?  When would you use each? What is the difference between the memory usage report in System Monitor and the one by free? The center of the dihedral group How to prove that the center of the dihedral group $D_{2n}$ is $\{1,r^{n}\}$ and the center of $D_{2n-1}$ is $\{1\}$?  I don't know how to prove it in this general case. Keyboard backlight not working on an Asus N56V See .  The FN keys are not working  Using answer in  I installed the asus-wmi-dkms_0.2_all.deb.gz package  Now, using xev I see that the keys emit keycodes (for backlight keys xev says for fn-f3 and fn-f4 keycode 237)  But no keyboard backlight, also volume keys have no effect  ================ original question ========================================  I cannot enable the keyboard backlight Seems that the leds class is missing I've not found the classes used in   Description of my framework:  ===========================================================  Machine: Asus N56V laptop  ===========================================================  Software   Kubuntu 12.04 amd64  kernel (3.5.0.5-generic) and drivers from xorg-edgers fresh X crack ppa   ===========================================================  Hardware and problems   after installation do not boot - SOLVED using boot-repair every couple of hours the system freezes - SOLVED using 3.5 kernel keybord FN keys - NOT WORKING Keyboard backlight - NOT WORKING Nvidia GEFORCE GT - NOT USED glxgears says 60 fps Ethernet Atheros card - SOLVED install alx driver external subwoofer - SOLVED adding options snd-hda-intel model=asus-mode4   ==========================================================  Solutions  see the answers to the  and  question.  ========================================================== Impose strict time-limit for questions on Hot Network Questions list Can Kakashi still use Susanoo after losing his Sharingan? When Kakashi had double Sharingan, he was able to use Susanoo. However, he lost the Sharingan.  Can he still use Susanoo without Sharingan now? Move object in inches instead of feet? Whenever I move an object in blender in unit mode(Imperial), it always make it in feet. For example, if I type G Y 12, it will move 12 feet. How can I make it move 12 inches instead? A number of questions "has been" or "have been" asked? Formally, is it correct to write:     A number of questions has been asked here.   or:     A number of questions have been asked here.   As a non-native speaker of English, I would prefer the former: the subject seems to be "number", therefore the verb ought to be singular, I'd say. However, the latter seems more common, and therefore I believe that my gut feeling is just plain wrong — but I would really like to have a definite answer.  Moreover, is it the same for "a myriad of", "a plethora of", and so on?