I would like to create a folder in my OPT directory on Ubuntu 14.04. However, it must have the following requirements:   Can not be deleted by ANYONE, even root. ReadOnly access to ALL users (except nobody) Write access ONLY by my user (test-user). Root shouldn't be able to write.
Without using sudo, preferably?
$$\lim_{x \to 0} \frac{f(x)}{|x|}=1$$ Then prove that $f$ is not differentiable at $0$. I was given this assignment and I'm not sure about my proof.. it feels like I'm assuming too much and not explaining with enough detail. Is there anything I need to add to make it sufficient? Assume toward contradiction that $f$ is differentiable at $0$. Then by definition we know that $f$ is continuous at $0$. Therefore $\lim _{x\to 0}f\left(x\right)=f\left(0\right)$ We know that $\lim _{x\to 0}\frac{\left(f\left(x\right)\right)}{\left|x\right|}=1$ Therefore we can conclude $\lim _{x\to 0}\frac{\left(f\left(x\right)\right)}{\left|x\right|}\cdot \left|x\right|=1\cdot 0=0$ But we can also rewrite this as $\lim _{x\to 0}\left(f\left(x\right)\right)\cdot \frac{\left|x\right|}{\left|x\right|}=f\left(0\right)\cdot 1=0$ Therefore $f(0) = 0$. Since $f$ is differentiable at $0$ we have $\lim _{x\to 0}\frac{\left(f\left(x\right)-f\left(0\right)\right)}{x-0}=\lim _{x\to 0}\frac{\left(f\left(x\right)-0\right)}{x}=\lim \:_{x\to \:0}\frac{\left(f\left(x\right)\right)}{x}\cdot \frac{\left|x\right|}{\left|x\right|}=\lim \:\:_{x\to 0}\frac{\left(f\left(x\right)\right)}{\left|x\right|}\cdot \:\frac{\left|x\right|}{x}$ Since the one sided limits of $\frac{f\left(x\right)}{\left|x\right|}$ exist, and are both equal to 1, we have $\lim \:_{x\to 0^+}\frac{\left(f\left(x\right)\right)}{\left|x\right|}\cdot \:\:\frac{\left|x\right|}{x}=\lim \:_{x\to \:0^+}\frac{\left(f\left(x\right)\right)}{x}\cdot \:\:\:\frac{x}{x}=1\cdot 1=1$ $\lim \:_{x\to 0^-}\frac{\left(f\left(x\right)\right)}{\left|x\right|}\cdot \:\:\frac{\left|x\right|}{x}=\lim \:_{x\to \:0^-}\frac{\left(f\left(x\right)\right)}{-x}\cdot \:\:\:\frac{-x}{x}=1\cdot -1=-1$ Since the limit doesn't exist, we have a contradiction to the fact $f$ is differentiable at $0$. Therefore $f$ is not differentiable at 0. Avoiding the second leg of an international flight - different rates for a return ticket? Possible Duplicate:          I am in the process of booking a flight from LAX - ZUR. I found a flight for approx. 1100 USD. However, if I book that flight and then continue, after a 5 hour layover, onward to SVO, The flight is approx. half of the initial price, and the first leg of the second flight is the exact same flight as the first booking. Assuming I travel light and do not check any baggage, are there any potential issues with this? Seems like a hell of a way to save a good chunk of change. Blender 2.78 file size grows and does never shrink I made a huge project, wanted to reduce file size from 1.3GB to below 1GB. Compressing did not help. I removed objects from scene. Also textures. I then realized, the file size even was the same when I delete ALL objects. Why?  Download of sample:   Before deleting all: 1.2GB, after: 1.1GB. Possible Duplicate:          On  it's a stated fact that if $I$ and $J$ are coprime ideals of a ring $A$, then $I^k$ and $J^\ell$ are also coprime for any integers $k,\ell$.   There's no proof given. Why is this fact true? Limits of sequences of sets I'm a simple minded Bayesian who feels comfortable in the cosy world of Bayes.   However, due to malevolent forces outside my control, I now have to do introductory graduate courses about the exotic and weird world of frequentist statistics. Some of these concepts seem very weird to me, and my teachers are not versed in Bayes, so I thought I'd get some help on the internet from those who understand both.   How would you explain the different concepts in frequentist statistics to a Bayesian who finds frequentism weird and uncomfortable?   For example, some things I already understand:   The maximum likelihood estimator $\text{argmax}_\theta \;p(D|\theta)$ is equal to the maximum posterior estimator $\text{argmax}_\theta \;p(\theta |D)$, if $p(\theta)$ is flat.  (not entirely sure about this one). If a certain estimator $\hat \theta$ is a sufficient statistic for a parameter $\theta$, and $p(\theta)$ is flat, then $p(\hat \theta|\theta)=c_1\cdot p(D|\theta)=c_1\cdot c_2\cdot p(\theta|D)$, i.e. the sampling distribution is equal to the likelihood function, and therefore equal to the posterior of the parameter given a flat prior.    Those are examples of explaining frequentist concepts to someone who understands Bayesian ones.   How would you similarly explain the other central concepts of frequentist statistics in terms a Bayesian can understand?  Specifically, I'm interested in the following questions:   What is the role of Mean Square Error? How does it relate to Bayesian loss functions? How does the criterion of "unbiasedness" relate to Bayesian criteria? I know that a Bayesian will not demand that its estimators are unbiased, but at the same time, a Bayesian would probably agree that an unbiased frequentist estimator is generally more desirable than a biased frequentist one (even though he would consider both to be inferior to the Bayesian estimator). So how does a Bayesian understand unbiasedness? If we have flat priors, do frequentist confidence intervals somehow coincide with Bayesian ones?  What in the name of Laplace is going on with specification tests like the $F$ test? Is this some degenerate special case of a Bayesian update on the distribution over model space?    More generally:  Is there some resource that explains frequentism to Bayesians?  Most of the books run the other way around: they explain Bayesianism to people who are experienced in frequentist statistics.     ps. I have looked, and while there are a lot of questions already about the difference between Bayesian and Frequentism, none explicitly explain Frequentism from the perspective of a Bayesian.   is related, but is not specifically about explaining Frequentist concepts to a Bayesian (more about justifying frequentist thinking in general).  Also, my point is not to bash frequentism. I really do want to understand it better Why can't I destroy or place blocks? I'm using the word "Zwei-Drittel-Abstimmungsmehrheit" a bunch of times in my document. Often it won't fit into the current line, extending into the right margin.  I figured out that the following package helps :  \usepackage[shortcuts]{extdash}    Then I can write  Zwei\-/-Drittel\-/Abstimmungs\-mehrheit   and the hyphenation is done correctly.  Is there a way that I can set this hyphenation globally for this word? Like i can do it with the command  \hyphenation{...}   Sadly this command doesn't work for words containing dashes. Have red shifted photons lost energy and where did it go? What are Virtual Methods? Why would you declare a method as "virtual".   What is the benefit in using virtual? Is there a streaming API for JSON? Is DOM the only way to parse JSON? What is a good set of naming conventions to use when developing on the Force.com platform? I've looked in the Apex developer's guide and a saw the   which has basically only has this:   We recommend following Java standards for naming, that is, classes start with a capital letter, methods start with a lowercase verb, and variable names should be meaningful.   I'm looking for something more in depth, such as end all Controllers with Controller and their tests with ControllerTest, etc.  What is a good set of naming conventions to use when developing on the Force.com platofrm?  It would be preferable if the answer has something that handles custom objects, classes, visualforce pages, and components and not just Apex classes. I can copy, move, create, and delete them. I can rename them using the REN command from a command prompt. I cannot rename folders through Windows Explorer anywhere on my machine, including on other drives.   When I try to do so, I receive an error titled "Rename Folder" that says "Can't find the specified file. Make sure you specify the correct path and file name." Then when I click Try Again or Cancel, I get another error titled "Rename" that says "The file or folder does not exist."  As far as I can tell, nothing else is wrong with my computer, but I'm pulling my hair out trying to fix this problem. I don't know for sure if superuser is the right place to ask this question, but feel free to redirect me.  Summary of Failed Attempts:   Booted into Safe Mode  Made a New User Account System Restore Point (two days ago, 9 days ago)  Deleting / Restoring / Modifying FolderDescriptions registry entries SFC /scannow  Removing windows update KB2984006  Scanned for viruses using Nod32  Scanned for malware using MalwareBytes   Details:  Tried rolling back to two different system restore points, both immediately before I observed the problem and one release prior to that.  Tried restoring FolderDescriptions registry entries as found here:   Booting in safe mode as suggested here:   SFC /scannow as suggested here:   Tried removing registry keys and windows update KB2984006 as suggested here:   Tried exporting folderdescriptions from other machine and importing as suggested here:   Compared my exported registry with other machine's exported registry for both:  HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\FolderDescriptions HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\Explorer\FolderDescriptions   My FolderDescriptions branch of the registry in both cases are binary equal to those exported from my wife's Windows 8.1 laptop which works fine. In my , I provided the following, problematic,  wording (especially bold italic), and I need help to better understand this issue so I can fix my answer:1          The thing is the books. (Reduced form of Sentence 2.a)         Fundamentally, Sentence 2.a (the so-called "correct" answer), is grammatically defective. Recall there is another grammatical rule: the subject and subject's complement should match in number.    A clarification is needed here. I am not suggesting here, in this EL&amp;U question, that there is any such singular grammatical rule as indicated in the quote above.  The quote continues as follows:     The reduced sentence makes the disagreement between the subject's and complement's plurality obvious. What is one to do? Language is linear and we know "The thing is X" is better than "The thing are X", so we go with the former, which is the subject-verb agreement rule. But what is "the books" then? It must be thought of as a collective noun, even if it doesn't look or feel like one. Forcing something to be a collective noun is related to the idea of notional agreement.   Others noted that grammatically defective is too strongly worded.  There is no such "grammatical rule" for subject/complement agreement.  Please help me understand/improve upon my line of thought here.  I'm stating that Sentence 2.1 presents a fundamental "conflict" or "error" (however one might define error) at some level (morphological, syntax, grammatical, semantic):     The thing is the books.  (Or, "The thing is the objects.")   Based on the "obvious" morphosyntactic plurality conflict, the above sentence feels so wrong that I think many native speakers would think it "simply" grammatically incorrect. However, @F.E. gives counter examples:     And here are some more grammatical examples, where the number of subject and predicative complement don't agree: "They were a problem to us all", "That so-called work of art is simply four pieces of driftwood glued together" (CGEL, page 254-5). As CGEL says: "What is required is semantic compatibility, not syntactic agreement . . .". There are more examples on page 512: "The only thing we need now is some new curtains", "The major asset of the team is its world-class opening bowlers", "Our neighbors are a nuisance", "This gadget is five different tools in one".   I think all the examples given above can be explained as notional agreement.    Question 1: If we explain this phenomena in terms of notional vs syntactic agreement, where does "grammatically correct/incorrect" fit in?  Question 2: Can a simple sentence such as "The thing is the objects." be grammatically incorrect while more complex sentences such as "The thing is four pieces of driftwood glued together." be grammatically correct?  (The answer, in my mind, must be no; this is my conundrum.)  Question 3: Would it be better to say that Sentence 2.a has a low level of (linguistic) ?   Question 4: How about a low level of  and that it's semantically difficult to be (linguistically) ?    Question 5: Do we simply draw a hard line and say "The thing is the objects." is 100% grammatically correct?  I didn't particularly like this option based on intuitive notions of "grammatically correct".    1. Please help me and be kind; I'm trying to improve my understanding. I'm looking for cool, objective advice on how to look at this.  I numbered my questions so they can be easily referenced, if desired.  My preference is the final answer would sufficiently answer all the questions, but of course that can be done explicitly or implicitly. Why does a subpanel need separate ground and neutral? Why does a power sub panel have to have separate neutral and ground bars other than code satisfaction?  Does a sub panel need a main breaker if there is one at the main?   Also, does the sub panel need a ground wire connected back to the main panel in the same building? I am currently visiting the USA from the UK (I am a UK citizen) and am intending on staying here for the full 90 days under the Visa Waiver Program.     How long would I have to stay out of the US at the end of this period before returning again?    Would I have to return to the UK, or could I stay with friends in another country (such as Canada) for a while? How do I add a new language? The aftermarket ROM I use seems to have the language list parred down to just a couple selections, probably to save space.  I would like to add a language back into the system. I can already set the locale using programs such as  so that applications with my language support start with the right locale code, however that doesn't add missing system languages. Having the system in another language would be nice, but the main thing is getting the dictionary files for the keyboard auto-complete. How does one go about adding the language support files for an input language to a system or ROM?  I can access other ROM's or the AOSP project to rip things out, but I don't know where to start. What files do I need and what modifications need to be made? Is there an easy way to do this with say a language-pack or is it hackery all the way?  My ROM is fully rooted and I have adb access if necessary. It's Android 2.3.7 () and I'm using the stock Android keyboard. The language I want is Turkish, although unless somebody has a download to point me to it's mostly the process I'm looking for here. The problem is, it seems when I enable a disabled module, the module's schema version in the system table is automatically updated to the latest version supplied by hook_update_N.  So my current module with the schema version -1 is modified to 7106 when I enable the module, and no hook_update_N functions are run.   So when I come to the next step of running database updates, no hook_update_N functions are run because the module thinks it's already the correct version.  The only method I can see is to manually set the module version in hook_enable, however I'll then need to update the module code to remove the hook_enable to make sure it doesn't run if the module is ever re-enabled in the future, so obviously this approach is a bit dirty.  I'm hoping there's a better solution? how to glob every hidden file except current and parent directory I want to glob every hidden file and directory, but not the current (.) and parent directory (..).  I am using bash.  Observe current behaviour:  $ ls -a .  ..  ...a  ...aa  ..a  ..aa  .a  .aa  .aaa  a $ echo * a $ echo .* . .. ...a ...aa ..a ..aa .a .aa .aaa   I would like .* to behave like this  $ echo .* ...a ...aa ..a ..aa .a .aa .aaa   There is the shell option dotglob  $ shopt -s dotglob   that works in a way; now I can use * to glob everything (hidden or not) but not . and ..  $ echo * ...a ...aa ..a ..aa .a .aa .aaa a   but now I can't differentiate between hidden or not. Also, .* still globs . and ..  $ echo .* . .. ...a ...aa ..a ..aa .a .aa .aaa   Is there a way to make .* not expand to . and ..? Should flawed questions be closed immediately? Possible Duplicate:          Given a question that is not clear at first, which satisfies the criterion for being "not a real question":      "It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot   be reasonably answered in its current form."   should that question be closed immediately, or should the OP get a chance to improve the quality of his question.  My modus operandi is this: When I encounter a question which is "not a real question", I respond via a comment - I might ask one or more counter-questions (about the issue), I might comment that I don't understand the question. So, I let the OP know that his question should be improved. I then give the OP say 15 minutes to respond (and in most cases the OP does respond). However, if the OP doesn't respond, then I consider voting for "not a real question".  Is this how SO should work?   I have witnessed in the past several questions for which I saw potential, being closed immediately, and I wonder if that is appropriate.   Edit: Of course, questions that are duplicates should be closed immediately, and off-topic questions should also be moved / closed immediately. In this question I am specifically referring to those questions which "have potential" (which could be corrected / improved)..