class.getResourceAsStream returns null on user's machine, how to reproduce?
What is a NullPointerException, and how do I fix it?
Classification of automorphisms of projective space Let $k$ be a field, n a positive integer.  Vakil's notes, 17.4.B: Show that all the automorphisms of the projective scheme $P_k^n$ correspond to $(n+1)\times(n+1)$ invertible matrices over k, modulo scalars.   His hint is to show that $f^\star \mathcal{O}(1) \cong \mathcal{O}(1).$ (f is the automorphism. I don't if $\mathcal{O}(1)$ is the conventional notation; if it's unclear, it's an invertible sheaf over $P_k^n$) I can show what he wants assuming this, but can someone help me find a clean way to show this? I went to the doctor's I have run across such a sentence:     Yesterday I was ill, so I went to the doctor's.   What is the function of possessive here, that is doctor's? Are there specific techniques/filters for snowscapes? Any way to send a personal message to another user? What does f-stop mean? I am crawling some data using Apache Nutch and storing it on my USB Drive. The OS itself is Ubuntu Live Boot OS. But for every restart or shutdown I am losing my data. I also tried suspending my Ubuntu user still data was not visible when I reinserted my live USB.  Is there any way I can keep the data intact and does not loose and application settings installations when I do restart Ubuntu.  Used USB installer provided by pendrivelinux.com at I am not an expert of random forest but I clearly understand that the key issue with random forest is the (random) tree generation. Can you explain me how the trees are generated? (i.e. What is the used distribution for tree generation?)  Thanks in advance ! I often see "replace with" and "replace by" used interchangeably, but this doesn't sound right to me:     I replaced that component by this one.   I would use "with" in such a sentence. "By" only seems reasonable in passive, although "with" sounds like it would there work too:     That component was replaced by this one.   That component was replaced with this one.   In my native language, the equivalent of "replace by" can only be used in passive, and even then it's a bit weird unless a person is the object replacing something – perhaps this affects my judgment?  Web searches haven't come up with anything conclusive; the results are contradictory and speculative at best.  Are "replace with" and "replace by" interchangeable in active context? What about passive? Are there stylistic reasons to prefer one over the other? Prove no solution to $x^2\equiv3\bmod5$ Show that there is no solution to the congruence $x^2\equiv3\bmod5$.   I'm not sure if the fact that the only numbers divisible by $5$ are those ending in $0$ or $5$ will help&hellip; Under Wild Shape it says "assume the shape of a beast" you have seen before. Does this mean they can only transform into creatures that have the beast type, such as bear, wolf, crocodile, etc.? Or can they turn into things with other types, like dragon, monstrosity, humanoid, fiend, etc.? I am new and struggling with java and I need assistance with code. Value keeps resetting to default I know that I can use something like cat test.txt | pr -w 80 to wrap lines to 80 characters  wide, but that puts a lot of space on the top and bottom of the printed lines and it does not work right on some systems  What's the best way to force a text file with long lines to be wrapped at a certain width?   Bonus points if you can keep it from breaking words. What would be the disadvantages of using a 4 stranded ethernet cable? I got this cable with a homeplug AV 200 device - its labelled cat 5e    But looking at the plug end has me rather dubious about it.   (There's only 4 strands there, not the standard 8 - and missing pins, so I suspect these cables are designed to do so. The wire jacket is also surprisingly loose).  Another angle. This isn't a standard connector, no, someone has went and made a non standard connector specifically for this    I figured the cable was crap so I cut into it - some of you were wondering if they had merely left out the additional pairs - and the answer is no - its basically half a cat 5 cable.    I'm currently using it for some legacy equipment that runs on fast ethernet and the plug it came with and it seems to work. However, I'm curious - what're the downsides of such a cable? What do I need to look out for? In what situations would this cat-5 cable be unsuitable for use in anything other than a ethernet cat o'nine tails? What is the difference between g++ and gcc? Is "The empty set is a subset of any set" a convention? Recently I learned that for any set A, we have $\varnothing\subset A$.  I found some explanation of why it holds.     $\varnothing\subset A$ means "for every object $x$, if $x$ belongs to the empty set, then $x$ also belongs to the set A". This is a vacuous truth, because the antecedent ($x$ belongs to the empty set) could never be true, so the conclusion always holds ($x$ also belongs to the set A). So $\varnothing\subset A$ holds.   What confused me was that, the following expression was also a vacuous truth.     For every object  $x$, if $x$ belongs to the empty set, then $x$ doesn't belong to the set A.   According to the definition of the vacuous truth, the conclusion ($x$ doesn't belong to the set A) holds, so $\varnothing\not\subset A$ would be true, too.  Which one is correct? Or is it just a convention to let $\varnothing\subset A$? How to fix slow wireless on machines with Intel wireless cards? I have looked through all the previous questions but turning power management off for the Wi-Fi card didn't work. This problem seems to be with the Lenovo Thinkpads. I switched to Ubuntu 11.10 from Windows 7 3 days ago so I'm new to the operating system. Print out elements from an array with a comma between elements except the last word In Windows there is a straightforward "Format" option in a flash drive's right-click pop-up menu. Where's that in Ubuntu? What are PATH and other environment variables, and how can I set or use them? Questions about    setting environment variables the PATH   are very common here, and in most cases the answers are very similar to each other. In the future it would be nice to have a good Q/A for this.  So the question is: What are environment variables, like the executable PATH, and how can I change and use them on major operating systems?  A good answer would include a simple explanation of what environment variables and especially PATH mean to the OS, as well as simple guidelines on how to set and read them accordingly. Possible Duplicate:          I'm working on a website that displays distance to various locations to the nearest 1/10 mile. One of the developers (a non-native speaker) asked me an interesting question: If the distance is 1.0 mile(s), is that singular or plural? Clearly, anything other that 1.0 is plural, but is it:     1.0 miles away   or     1.0 mile away   The first option sounds more correct to my ear, but the voice of my elementary school language arts tells me that the latter option is correct.  Edit: Added the word 'away' to the example. It doesn't change the question, but might provide clarity for the answer. Also, regarding numbers between 0 and 1, after more thought, I'm not sure that the answer is as clear as I originally thought. See .