Why didn't Voldemort's soul die in Harry when he was bitten by the basilisk in "The Chamber of Secrets"?
Why didn't the basilisk bite in Chamber of Secrets destroy the Horcrux?
Understanding the difference between two theorems related to $|G\,:\,K|=|H\,:\,K|\cdot|G\,:\,H|$. Android app crashes when clicking on the loading icon in notification pane App version 1.0.27  If you the notification pane and click on the loading icon while it's spinning, the app will cause the app to crash.  03-26 22:51:08.331 E/AndroidRuntime(5927): FATAL EXCEPTION: main 03-26 22:51:08.331 E/AndroidRuntime(5927): java.lang.ArrayIndexOutOfBoundsException: length=0; index=-1 03-26 22:51:08.331 E/AndroidRuntime(5927): at java.util.ArrayList.get(ArrayList.java:310) 03-26 22:51:08.331 E/AndroidRuntime(5927): at com.stackexchange.marvin.ui.BaseActivity$3.onItemClick(BaseActivity.java:266) 03-26 22:51:08.331 E/AndroidRuntime(5927): at android.widget.AdapterView.performItemClick(AdapterView.java:298) 03-26 22:51:08.331 E/AndroidRuntime(5927): at android.widget.AbsListView.performItemClick(AbsListView.java:1100) 03-26 22:51:08.331 E/AndroidRuntime(5927): at android.widget.AbsListView$PerformClick.run(AbsListView.java:2788) 03-26 22:51:08.331 E/AndroidRuntime(5927): at android.widget.AbsListView$1.run(AbsListView.java:3463) 03-26 22:51:08.331 E/AndroidRuntime(5927): at android.os.Handler.handleCallback(Handler.java:730) 03-26 22:51:08.331 E/AndroidRuntime(5927): at android.os.Handler.dispatchMessage(Handler.java:92) 03-26 22:51:08.331 E/AndroidRuntime(5927): at android.os.Looper.loop(Looper.java:137) 03-26 22:51:08.331 E/AndroidRuntime(5927): at android.app.ActivityThread.main(ActivityThread.java:5103) 03-26 22:51:08.331 E/AndroidRuntime(5927): at java.lang.reflect.Method.invokeNative(Native Method) 03-26 22:51:08.331 E/AndroidRuntime(5927): at java.lang.reflect.Method.invoke(Method.java:525) 03-26 22:51:08.331 E/AndroidRuntime(5927): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737) 03-26 22:51:08.331 E/AndroidRuntime(5927): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553) 03-26 22:51:08.331 E/AndroidRuntime(5927): at de.robv.android.xposed.XposedBridge.main(XposedBridge.java:126) 03-26 22:51:08.331 E/AndroidRuntime(5927): at dalvik.system.NativeStart.main(Native Method)   (Think I should calm down on finding bugs for a little while? :P) Python List vs. Array - when to use? If you are creating a 1d array, you can implement it as a List, or else use the 'array' module in the standard library.  I have always used Lists for 1d arrays.  What is the reason or circumstance where I would want to use the array module instead?  Is it for performance and memory optimization, or am I missing something obvious? This is Ubuntu server 10.04 64 and samba 3.4.7.  I have a shared directory /home/mit/share and another one /home/temp that I link into the shared one:  ln -s /home/temp /home/mit/share/temp   But on windows, after using internet, I cannot open S:/temp, but on Linux it is possible to access /home/mit/share/temp like expected.   This works if I link directories inside /home/mit/share/temp, so I guess samba is restricting to jump with a link outside/above the shared directory.   EDIT:  See also this question titled .  It seems best to put unix extensions = no into the global section and follow symlinks = yes and wide links = yes only into the shares section, where you really need it.  The unix extension flag has to live in the global section and not in the individual shares sections. But for security reasons it is better to use the other options only where you need it, and not globally. Hero who is against enhancements but has some himself It is possible to migrate a question from one Stack Exchange site to another by closing, but if I have a question that I think is on-topic for multiple Stack Exchange sites, is it OK to post it on both (multipost)?   For example, I have a question that's earned me the tumbleweed badge on SO and I'm not sure what the best thing to do with it is. It's about a web server so it might be answerable on Server Fault but it's really more of a programming thing, hence the posting the question on Stack Overflow.    Is there any way to make the question visible on multiple sites (crosspost) and then accept the answer wherever it came from? I realised, reading another Phys.SE question about  that I don't really understand how  works. Particularly concerning, for a SCUBA diver.  The top answers to that question seem to claim that balloons get their "sense of down" from a pressure differential. They continue: when a car accelerates, the air at the back of the car becomes more dense, and at the front less dense, changing the plane of the pressure differential and so also, the balloon's sense of up. I find that extremely hard to credit. However, I realised that I don't really know why less dense things float in more dense things.  I'm fairly sure it's something to do with displacement of heavier things by lighter things, and I think pressure acting on the lighter thing's surface has something to do with it, but that's about it. Expected Number of coin flips for 2 consecutive heads for first time. I was working on problems on expectation and found this one as a question from a well-known exam  Assume that you are flipping a fair coin, i.e. probability of heads or tails is equal. Then the expected number of coin flips required to obtain two consecutive heads for the first time is.  (A)4  (B)3  (C)6  (D)10  (E)5  I worked up like Let N be the number of tosses required untill 2 consecutive heads are obtained for the first time.  Let the probability of obtaining heads be p and tails be q and for a coin p=q=1-p=1-q.  For N=2, the probability will be $p^2$  For N=3, the probability will be $p^2.q$  For N=4, the probability will be $q^2.p^2$  For N=5, the probability will be $q^3.p^2$  and so on...  Now, $E[N]=2(p^2)+3(p^2.q)+4(q^2.p^2)+5(q^3.p^2)+......$  and this comes out to be $\frac{3}{2}$ but it matches with none of the options.  Please tell me where I am wrong and what should I do to reach the correct solution? How to change the date format? Disabling SSLv3 but still supporting SSLv2Hello in Apache Many SSL clients, notably JDK 6, use the SSLv2Hello protocol to handshake with the server.  Using this protocol does not mean you are using SSL 2.0 or 3.0 for that matter; it is merely a handshake to determine which protocol to use.  [  However, in Apache, if you disable SSLv3 support, this apparently removes support for the SSLv2Hello protocol.  Apache Tomcat has explicit support for SSLv2Hello; that is, you can enable that, but not enable SSLv3.    Is there any way to do this in Apache?    [Update]   This is my protocol config:    SSLProtocol +TLSv1 +TLSv1.1 +TLSv1.2 -SSLv3 Why are some of my screen-recording/capturing/sharing applications (or app features) not working in Ubuntu 17.10 (and later releases)? best way to pick a random subset from a collection? I have a set of objects in a Vector from which I'd like to select a random subset (e.g. 100 items coming back; pick 5 randomly). In my first (very hasty) pass I did an extremely simple and perhaps overly clever solution:  Vector itemsVector = getItems();  Collections.shuffle(itemsVector); itemsVector.setSize(5);   While this has the advantage of being nice and simple, I suspect it's not going to scale very well, i.e. Collections.shuffle() must be O(n) at least. My less clever alternative is  Vector itemsVector = getItems();  Random rand = new Random(System.currentTimeMillis()); // would make this static to the class      List subsetList = new ArrayList(5); for (int i = 0; i &lt; 5; i++) {      // be sure to use Vector.remove() or you may get the same item twice      subsetList.add(itemsVector.remove(rand.nextInt(itemsVector.size()))); }   Any suggestions on better ways to draw out a random subset from a Collection? Inverse public-key encryption I'm in the need of an inverse public-key encryption method where you encrypt with the private key and decrypt with the public key. In other words an asymetric encryption where you can't generate the encryption key from the decryption key. Does such encryption exist? If yes which, and which would be the fastest?  If nothing like that exists I would be glad if you helped me out with my situation:    I need to authenticate users logging in from my Java application in the way that the response from the server cannot be falsified and thus giving the user full access to the application. Using public key encryption was an obvious method, I would decrypt data received from the client to confirm the credentials. This won't work because if someone manages to decompile and get the private key from the code, they would be able to generate the public key, which would make them able to crack my application again. So any ideas how I can get this secure? Restore Macintosh HD to its original partition configuration I have a program which spawns several child processes.  I want to know which files this program and its children are creating, deleting, and modifying.   inotifywait can tell me which files are being accessed, but cannot tell me which process is doing it. And I have to know where the files are being created in order to set up the monitor. auditctl will let me log which processes modify a file, but, again, I have to know where the files are in order to set up logging. lsof will tell me all of the files, but doesn't seem to be a good solution for real-time tracking.   Is there anything that will let me monitor a program's file manipulation without knowing a priori which files will be manipulated? My 3 years old doesn't tell me when he needs to use the bathroom My son is 3 years old and doesn't tell me when he needs to use the bathroom. It has been 5 months now that I took his diaper off him. I just do not know what I should do.  Should I put a diaper on him again?  I mean, is this normal? Please help. I get frustrated sometimes.  He doesn't want to potty at all! I did train him before but now that he understands, he doesn't want to go to potty. Is it possible to load some package from a .sty file only if some option is selected?  (Naive approach \DeclareOption{something}{\RequirePackage{something}} doesn't work.) QGIS locked into fullscreen mode on Ubuntu 12.04 No crash in this case, but I made the mistake of toggling to fullscreen mode on my netbook running Ubuntu 12.04. It's now impossible to escape , and it seems to have disabled the popout unity launcher as well. Steps I've already taken:   Alt-Tab to move to a different program, then back - QGIS remains in fullscreen Alt-V, Ctrl-F and F11 get no response I've unistalled QGIS, deleted the /.qgis/ profile data folder, and reinstalled. Still launches fullscreen   To add to the weirdness, it now launches - still in fullscreen - into a different workspace than the active one.  I realize this has the sound of a Unity problem, but it's just this program that has a malfunctioning UI.  Thanks to all the crew; this in no way changes my opinion of QGIS as an essential tool. Prove that for every $a\in A$ $\exists$ $q\in M,s\in A$ s.t. $a=sba+qa$ where $M$ is maximal ideal in $A$. Let A be a commutative ring with unity ring, M be a maximal ideal and $b\notin M$ . Show that there exists $q \in M, s\in A$ such that for every $a \in A$ we have $a=sba+qa$. Show that this is true only when $M$ is a maximal ideal.   Suppose if we take $A=2\mathbb Z$ and $M=4\mathbb Z$, $a=6.$ Then by the given statement $\exists$ $s\in A$, $q\in M$ s.t. $6=6(2s+q)$ $\implies$$s=\frac{1-q}{2}\implies q \text { is odd}$. But $q \in 4\mathbb Z.$  Please someone give some hints. how can solve this.  Thank you.. What is the difference between equation and formula? Sometimes equation and formula are used interchangeably, but I was wondering if there is a difference.  For example, suppose we can calculate a car's fuel efficiency as:  mpg = distance traveled in miles / the fuel used in a gallon   Is that an equation or formula?