How can I render an SSD permanently inoperable with no chance of data recovery?
How can I securely format a solid-state drive?
I would like to see an explicit example of a non-trivial elementary extension of the structure $(\mathbb{N}, +, \cdot, 0, 1)$ where $\mathbb{N}$ includes zero. Most of all I am interested in countable ones. Which X-Men movies should I watch before Deadpool? I want to watch Deadpool, but I have heard the character has appeared in X-Men series too. My question is, if I watch X-Men before Deadpool, will it enhance my interest in the Deadpool character? SEDE logs me out more often than it used to do I'm pretty sure that since a month or so,  seems much more eager to get rid of my session and log me out in that process. I don't mind logging in a couple of times per day, if that helps to reduce resource consumption, but the user experience isn't all that great when it happens. Here is why: I'm most often in the middle of writing a query for an MSE question, for example . So I have the edit window open and am creating a new revision of my query. When I click &quot;run,&quot; I do notice the button gets grayed-out, as it normally does, but I never get any result back. There is also no error message. To recover from this I have to copy the SQL text I have typed, open a new tab and load SEDE, log in, switch back to the stalled tab, refresh, paste the SQL text, run query. Repeat the process after 10 minutes. If the intended behavior is to log users out of their session on such short notice (I recall sessions lived for 24 hours), can there then be a slightly better handling in the browser of that state, so it is clear you're logged out once you click the run button? I prefer, however, to have the longer allowed sessions back. I'm experiencing this behavior mostly in Chrome on Win 10. Let $M$ be a smooth manifold and let $N$ be a manifold with boundary. If $dF_{p}$ is an isomorphism, then $F\left(p\right)\in\mbox{int}M $. Let $M$ be a smooth manifold and let $N$ be a manifold with boundary, both with the same dimension $n$. If $dF_{p}$ is an isomorphism, then $F\left(p\right)\in\mbox{int}N  $.  I am trying to prove this theorem to prove a result about smooth embeddings.  Here is how I am thinking the problem could be solved. Assume thet $F(p)$ is a boundary point of $N$. Then there exists a chart $(V,\psi)$ at $F(p)$ such that $\psi(V) $ is an open subset of the upper half space $\mathbb{H}^{n}$. I guess we have to use some fact about $M$ having no boundary and the the fact that $dF_p$ is an isomorphism to show that there is a contradiction, but I cannot figure that out. I have a script that needs to do some stuff based on file creation &amp; modification dates but has to run on Linux &amp; Windows.  What's the best cross-platform way to get file creation &amp; modification date/times in Python? If you have the ability to cast a spell without a spell slot, can you cast that spell using a spell slot? A 10th level Drow warlock (for instance) has the following Drow Magic racial trait (PHB p. 24), in addition to its warlock spellcasting abilities:  You know the dancing lights cantrip. When you reach 3rd level, you can cast the faerie fire spell once per day. When you reach 5th level, you can also cast the darkness spell once per day. Charisma is your spellcasting ability for these spells.  Can the Drow warlock cast faerie fire (which is not on the warlock spell list) using a warlock spell slot? Can it cast darkness (which is on the warlock spell list) using a warlock spell slot?  The  says this about the Magic Initiate feat:  If you’re a spellcaster, can you pick your own class when you gain the Magic Initiate feat? Yes, the feat doesn’t say you can’t. For example, if you’re a wizard and gain the Magic Initiate feat, you can choose wizard and thereby learn two more wizard cantrips and another 1st-level wizard spell. If you have spell slots, can you use them to cast the 1st-level spell you learn with the Magic Initiate feat? Yes, but only if the class you pick for the feat is one of your classes. For example, if you pick sorcerer and you are a sorcerer, the Spellcasting feature for that class tells you that you can use your spell slots to cast the sorcerer spells you know, so you can use your spell slots to cast the 1st-level sorcerer spell you learn from Magic Initiate. Similarly, if you are a wizard and pick that class for the feat, you learn a 1st-level wizard spell, which you could add to your spellbook and subsequently prepare.  But this specifically requires you to pick the feat for one of your classes to be able to cast the spell learnt using your class spell slots, and does not seem directly applicable. A Warlock can use warlock Pact Magic spell slots to cast spells learnt from levels of another spellcasting class, per the multiclass spellcasting rules (PHB p. 164):  If you have both the Spellcasting class feature and the Pact Magic class feature from the warlock class, you can use the spell slots you gain from the Pact Magic feature to cast spells you know or have prepared from classes with the Spellcasting class feature, and you can use the spell slots you gain from the Spellcasting class feature to cast warlock spells you know.  Similarly, if the warlock has learnt the invocation Mask of Many Faces (PHB p. 112)...  You can cast disguise self at will, without expending a spell slot.  ...Can the warlock cast disguise self using a spell slot, e.g. to decrease the chance it can be dispelled? How to solve the diffencial equation for power series $(1+x²)y'' - 6xy=0$ in $x_{0}=0$ I have tried for the power series but when suppose the solution is $y(x)=\sum _{n=0}^\infty a_nx^n$ appeared sums dependents of $a_n$,  $a_{n+2}$ and $a_{n-1}$ and this is not possible. 32 bit or 64 bit OS on a 512 mb VPS? I am planning to rent a VPS service with following basic specification:   512mb of RAM 1 CPU 20gb HDD (4gb of it is swap) Ubuntu 10.10 server   I am able to choose between a 32 bit or 64 bit install of Ubuntu server as the operating system.   My question is would it be better to chose a 32 bit operating system since I will have only 512mb of RAM, rather than using a 64 bit operating system and dealing with the additional overheads?  edit:  I have installed Ubuntu server 10.10 32 bit and 64 bit on VirtualBox. After a minimalistic installation with only ssh server, the 32 bit installation consumes 63mb of RAM when first boot up and 64 bit consumes 85mb of RAM.  After installing and running  daemon, 32 bit consumes 99mb of RAM when first boot up and 64 bit consumes 128mb. How can I communicate with a Unix domain socket via the shell on Debian Squeeze? I’m running a Debian Squeeze web server. I’ve installed memcached on it, and configured memcached to listen on a Unix domain socket (at /tmp/memcached.sock), as it only needs to receive messages from the website, which lives on the same server.  It seems to be working fine, but I’d also like to communicate with memcached via the shell, to check that it’s doing what I think it’s doing.  memcached accepts messages via a simple ASCII protocol (if I understand correctly). If it was listening on TCP/IP, I could send messages to it via e.g. nc:  $ echo "stats settings" | nc localhost 11211   But I can’t figure out how to send that text to the domain socket instead.  On my laptop (which runs OS X Lion), both nc and telnet have options (-U and -u respectively) to use domain sockets. However, on my Debian Squeeze web server, these options aren’t present. How do I enable hardware virtualization technology (VT-x) for use in Virtualbox? So I am trying to run Ubuntu in a virtualbox but on installing 12.10 from the .iso I was greeted by a warning telling me that audio wouldn't work then I pressed next and this popped up:  Failed to open a session for the virtual machine Tux 3 VT-x features locked or unavailable in MSR (VERR_VMX_MSR_LOCKED_OR_DISABLED) Details  Result Code:  E_FAIL (0x80004005) Component:  Console Interface:  IConsole {db7ab4ca-2a3f-4183-9243-c1208da92392}   And then it doesn't work.  I assigned 4GB of my 8GB to Ubuntu, 100 dynamically allocated GB of space, and 12MB of graphics memory. I'm running an Asus p8z77 V LX mobo with an Intel i5 3550 processor.   Downloaded 12.04.2 on my PC and tried again. Still getting the same message. Now the cubs are growing, fed on mom's milk, but mom herself hasn't eaten in five months, and is getting thinner by the day.   What does in mean here, and how would the meaning of that piece change if for were used? I just purchased an unlocked iPhone 5 from the Apple store today, and I can't activate it to use it because it says "please" insert a valid SIM card to use it. I'm not using this phone as a "phone" to make calls. I'm a developer and am just looking to use it for development purposes. How can I go about using the iOS 5? Prove $e^x - e^y \leq e |x-y|$ for $x$ belonging to $[0,1]$ I'm not sure how to go about this. Does it involve using MVT?  I got as far as saying $e = \frac{e^x - e^y}{x-y}$. "It's cold today" -- what term do linguists use to call "it" when it's used as the subject of a sentence, but has no real antecedent? Assume I have the following list:  foo = ['a', 'b', 'c', 'd', 'e']   What is the simplest way to retrieve an item at random from this list? How to install Microsoft fonts on Ubuntu 16.10? Show that every uncountable set of real numbers has a point of accumulation. Why does Python code use len() function instead of a length method? I know that python has a len() function that is used to determine the size of a string, but I was wondering why it's not a method of the string object.  Update  Ok, I realized I was embarrassingly mistaken. __len__() is actually a method of a string object. It just seems weird to see object oriented code in Python using the len function on string objects. Furthermore, it's also weird to see __len__ as the name instead of just len. Proving Binomial Identity without calculus How to establish the following identities without the help of calculus:  For positive integer $n, $ $$\sum_{1\le r\le n}\frac{(-1)^{r-1}\binom nr}r=\sum_{1\le r\le n}\frac1r $$  and  $$\sum_{0\le r\le n}\frac{(-1)^r\binom nr}{4r+1}=\frac{4^n\cdot  n!}{1\cdot5\cdot9\cdots(4n+1)}$$ Singular values of the data matrix and eigenvalues of the covariance matrix