I've been a teacher.     VS       I was a teacher.   I no longer teach, but I used to teach. Can I used "have been" here?  I have been a teacher
What is the difference between the three sentences below?   I have been married with her for three years. I was married with her for three years. I married her for three years.
Non-interleaved vertex buffers DirectX11 I'm using Chrome 32 on an Android tablet (not phone) and just can't figure out how to close all open tabs in one go. Use a specific forwarded key from SSH-agent? Let's say I have a key for Github, along with other keys. I've added lots of keys to my ssh agent (ssh-add -L returns lots of lines) at my home computer A. In my .ssh/config I have set up which key to use with which host, so e.g.  ssh -T -vvv git@github.com 2&gt;&amp;1 | grep Offering   gives  debug1: Offering RSA public key: /Users/doxna/.ssh/id_rsa.github   Only one key is offered, as expected. But then ssh-ing to some host B with ForwardAgent yes and repeating the same command, I get  debug1: Offering RSA public key: /Users/doxna/.ssh/id_rsa.linode2 debug1: Offering RSA public key: /Users/doxna/.ssh/id_rsa.helium debug1: Offering RSA public key: /Users/doxna/.ssh/id_rsa.github   meaning it tries all my keys. This is problematic since only a limited number of keys can be tried before servers return Too many authentication failures. So I tried editing .ssh/config on host B to include  Host github.com   IdentityFile /Users/doxna/.ssh/id_rsa.github   IdentitiesOnly yes   but then I get no key offerings, but rather  debug2: key: /Users/doxna/.ssh/id_rsa.github ((nil))   which I guess means that the key was not found(?) And after all, the key is located at my home computer A, not host B, so the question is how to refer to it at host B? Hope I managed to explain the question. Have a look at the following code:  \documentclass[letterpaper]{article} \usepackage{amsmath,amssymb} \begin{document}  $2-\frac{2}{1-\left(\frac{2}{2-\frac{2}{x^2}}\right)}$\quad  $2-\dfrac{2}{1-\left(\dfrac{2}{2-\dfrac{2}{x^2}}\right)}$\quad  $2-\cfrac{2}{1-\left(\cfrac{2}{2-\cfrac{2}{x^2}}\right)}$\quad  $2-\dfrac{2}{1-\left(\cfrac{2}{2-\dfrac{2}{x^2}}\right)}$ \end{document}   This gives:    Evidently, the first display is not the proper way. The second and last are the same I guess. The third has a better display but there is too much space above the 2 in \left(\cfrac{2}{2-\cfrac{2}{x^2}}\right). Essentially, non of the above displays satisfies, for me, a good Mathematical typsetting. Although, it may be argued that it is the default in LaTeX. I just can't get it right? Any insights? In a book I got this example from it looks like this without the excessive bold (this is a scanned image): I recently traveled from the Basel area to Stuttgart for a weekend.  I had round-trip tickets including (paid) bicycle reservations.  At our first station change, we found that our EC train was canceled.  Information gave us a replacement train schedule, using slow RE trains which don't require reservations for bicycles.  As we continued our trip, every single train we boarded arrived late, eventually causing us to reach Stuttgart roughly 2 hours later than our initial itinerary.  What monetary compensation am I justified in requesting from Deutsche Bahn in this case?  In particular:   It seems clear I should get back the bicycle reservation money, since the train we reserved on was canceled. I know DB offers compensation for late travels.  I'm not sure whether we were 2 hours late or more, or just shy of 2 hours.  But does this apply if we weren't traveling by our original trains? If we had originally scheduled our journey with RE trains and other local transport, we could have bought a Baden-Württemberg ticket for much cheaper than our tickets including an EC cost.  Can I ask them to refund the difference? Am I entitled to any other type of compensation? Difference between char *str="STRING" and char str[] = "STRING"? Why can we flag/vote a question on Meta as duplicate of another question which has no accepted/upvoted answers? When we flag/vote-to-close a question as a duplicate on Stack Overflow, and that potential duplicate doesn't have any upvoted or accepted answers, we are alerted that we can't use that question as a duplicate and can't continue. This same check does however not seem to apply to Meta questions. Why not? Traditional statistical tests, like the two sample t-test, focus on trying to eliminate the hypothesis that there is no difference between a function of two independent samples. Then, we choose a confidence level and say that if the difference of means is beyond the 95% level, we can reject the null hypothesis. If not, we "can't reject the null hypothesis". This seems to imply that we can't accept it either. Does it mean we're not sure if the null hypothesis is true?   Now, I want to design a test where my hypothesis is that a function of two samples is the same (which is the opposite of traditional statistics tests where the hypothesis is that the two samples are different). So, my null hypothesis becomes that the two samples are different. How should I design such a test? Will it be as simple as saying that if the p-value is lesser than 5% we can accept the hypothesis that there is no significant difference? True for every formula. For a formula $ \gamma = r \iff (p_1 \vee p_2) $ there is true that: $\rho \models \gamma \iff \rho(r) = \max(\rho(p_1), \rho(p_2))$  Is it a true for every formula r? Sharing Jupyter notebooks within a team I would like to set up a server which could support a data science team in the following way: be a central point for storing, versioning, sharing and possible also executing Jupyter notebooks.  Some desired properties:   Different users can access the server and open and execute notebooks that were stored by them or by other team members. The interesting question here is what would be the behavior if user X executes cells in a notebook authored by user Y. I guess the notebook should NOT be changed: Solution should be self-hosted. Notebooks should be stored either on the server or on Google drive or on self-hosted instance of owncloud. (Bonus) Notebooks will be under git versioning control (git may be self-hosted. Cannot be bounded to GitHub or something of that sort).   I looked into  and . With the former, I didn't understand how to allow cross users access. The latter seems to only support GitHub as the storage of the notebooks.  Do you have experience with either of the solutions? Vim not displaying Input mode (14.04) When I open up the Vim editor, it's supposed to show at the bottom of the screen whether I'm in Input mode or not. But it stays blank whether I'm in Command mode or in Input mode.  Also, vimtutor doesn't work. All I get is a blank screen without any instructions.  It's the same whether I open up a terminal or use a virtual console.  Any ideas what might be wrong? Is there any way other than instanceof operator for object type comparison in java? I remember reading in some Java book about any operator other than 'instanceof' for comparing the type hierarchy between two objects.  instanceof is the most used and common. I am not able to recall clearly whether there is indeed another way of doing that or not. Is there any built-in software or terminal method allowing me to view the hardware profiles on my system? Windows equivalent of such a feature would be Device Manager. Let $W^{1,p}(U)$ be the Sobolev space. Suppose that $U$ is connected bounded domain in $\mathbb{R}^n$ and $u \in W^{1,p}(U)$ satisfies $Du=0$ a.e. in $U$. How can I prove that $u$ is constant a.e. in $U$? Case insensitive regular expression without re.compile? Headers of \chapters* take the headers of their previous \chapter When using book.cls and using \chapter* after a \chapter, the header used in \chapter* is wrong. An example is pasted below.   Is there any known workaround for that? I have tried quite some tricks without success.   \documentclass[]{book}  \begin{document}  \chapter{First Chapter} aslkjdf  \chapter*{Unnumbered Chapter} The GNU General Public License is a free, copyleft license for software and other kinds of works.  The licenses for most software and other practical works are designed to take away your freedom to share and change the works. By contrast, the GNU General Public License is intended to guarantee your freedom to share and change all versions of a program--to make sure it remains free software for all its users. We, the Free Software Foundation, use the GNU General Public License for most of our software; it applies also to any other work released this way by its authors. You can apply it to your programs, too.  When we speak of free software, we are referring to freedom, not price. Our General Public Licenses are designed to make sure that you have the freedom to distribute copies of free software (and charge for them if you wish), that you receive source code or can get it if you want it, that you can change the software or use pieces of it in new free programs, and that you know you can do these things.  To protect your rights, we need to prevent others from denying you these rights or asking you to surrender the rights. Therefore, you have certain responsibilities if you distribute copies of the software, or if you modify it: responsibilities to respect the freedom of others.  For example, if you distribute copies of such a program, whether gratis or for a fee, you must pass on to the recipients the same freedoms that you received. You must make sure that they, too, receive or can get the source code. And you must show them these terms so they know their rights.  Developers that use the GNU GPL protect your rights with two steps: (1) assert copyright on the software, and (2) offer you this License giving you legal permission to copy, distribute and/or modify it.  For the developers' and authors' protection, the GPL clearly explains that there is no warranty for this free software. For both users' and authors' sake, the GPL requires that modified versions be marked as changed, so that their problems will not be attributed erroneously to authors of previous versions.  Some devices are designed to deny users access to install or run modified versions of the software inside them, although the manufacturer can do so. This is fundamentally incompatible with the aim of protecting users' freedom to change the software. The systematic pattern of such abuse occurs in the area of products for individuals to use, which is precisely where it is most unacceptable. Therefore, we have designed this version of the GPL to prohibit the practice for those products. If such problems arise substantially in other domains, we stand ready to extend this provision to those domains in future versions of the GPL, as needed to protect the freedom of users.  Finally, every program is threatened constantly by software patents. States should not allow patents to restrict development and use of software on general-purpose computers, but in those that do, we wish to avoid the special danger that patents applied to a free program could make it effectively proprietary. To prevent this, the GPL assures that patents cannot be used to render the program non-free.  The precise terms and conditions for copying, distribution and modification follow.  \end{document} Is irrational times rational always irrational? Is an irrational number times a rational number always irrational?  If the rational number is zero, then the result will be rational. So can we conclude that in general, we can't decide, and it depends on the rational number? Shortcut for "null if object is null, or object.member if object is not null" What does the comma operator do? Why can partial derivatives be exchanged? In the   post in this stack exchange, one of the answers to the questions of do partial derivatives commute is: Second order partial derivatives commute if f is $C^2$ (i.e. all the second partial derivatives exist and are continuous). This is sometimes called Schwarz's Theorem or Clairaut's Theorem. This theorem is in my textbooks, yet I cannot seem to find the proof in them. I have tried proving the theorem yet I have gotten stuck. So, what is the proof of Clairaut's Theorem, or why do partial derivatives commute? If the proof is too long, a link to the proof with an intuitive explanation will be sufficient.