How can I solve this question mathematically?  There are two paths $A$ and $B$, in each path there is a person, one of them is a liar and the other is a truth teller. I want to know the right path, so what is the question that I should ask only one of them. and be sure about the right path?
So i was solving exercises in propositional logic lately and stumbled upon a puzzle, that goes like this:     Each inhabitant of a remote village always tells the truth or always lies. A villager will only give a "Yes" or a "No" response to a question a tourist asks. Suppose you are a tourist visiting this area and come to a fork in the road.    One branch leads to the ruins you want to visit; the other branch leads deep into the jungle. A villager is standing at the fork in the road. What one question can you ask the villager to determine which branch to take?    I intuitively guessed the answer is "If I asked you this path leads to the ruins, would you say yes?". So my questions are:   What is the name and/or source of this logical riddle? How can i corroborate my answer with mathematical rigor?
Where is the itoa function in Linux? Is it possible to upgrade a BGA 1224 CPU? I want to upgrade the CPU of my T430s laptop from i7-3520M to i7-3632QM. I'm sure i7-3632QM is supported (same socket (BGA1224), same TDP (35W) and microcode found in BIOS (306A9.PAT)).  So my question is: 1) is it possible to de-solder the current CPU without damaging it, and to solder the new CPU without damaging it and the motherboard ? 2) if so, what tools are necessary? who can do that at a reasonnable cost?  Until now, I was unable to find anyone able (or willing) to do that (I'm located in France, and I have tried a local fablab, electronics shops, TV repair shops, ...). Any hint would be appreciated. I know standing in line to get a visa is never fun, but was wondering if any Americans had experience getting a standard tourist "L" visa in Hong Kong.   I'm leaving on a RTW trip in less than two weeks and I plan on being in China around June. So I either need to get a 6 or 12 month multi-entry visa before I leave the USA - which would entail booking all my flights and accommodation and securing an invitation letter in the next few days - or just fly to Hong Kong before going to China in June.   Hong Kong seems like the simplest answer, but China usually doesn't allow Americans to get visas outside of their home country (HK seems to be an exception). I just wanted to know if any Americans had done it successfully.  Update: The Chinese Visa Office in HK currently has this notice on their website: "If you don't reside or work in Hong Kong permanently, you are required to apply Chinese visa from the Embassy or Consulate-General of Peoples' Republic of China in your resident country." It seems practices may have changed. Any Americans with experience care to contradict this?  Link: CSS bug with printing site pages (now with 100% more suggested fix included!) How can you explain that this double negation is not a double negation? Is there a rule in English about this kind of sentence?  PS / Do I have to mention Pink Floyd Copyright ? :-)  Edit : Since there are a lot of Pink Floyd related explanation, I'll bring a Freddy Mercury one : "I don't have time for no monkey business", which I also understand as "I don't have time for monkey business". Am I right ? Remotely run script on Unix, get output locally? I need to run a (Tcl, or whatever) script on a remote Unix machine, from a (local) Windows command shell, and I want the stdout/stderr of the script to show up in the Windows CLI. The exit code would also be useful.  Is this possible using ssh (putty)? Or by any other means?  Thanks! Protect email addresses in the user description from bots I've noticed that emails are not protected in the user description. For example  entered his email and when viewing the source code of the page it is plain text that malicious bots could harvest and exploit to spam. It would be nice if email addresses were automatically encoded to prevent this. How can I use the compositor on the result of the sequencer? I recently ran a renderfarm on a file with some compositing setup, but I forgot to set the composite output back to the Composite node instead of the Viewer I was temporarily using. Since the node setup didn't require anything besides the image data (i.e., no Z-buffer, object IDs, etc.) I figured that I could just run the compositor on each frame individually. However, this proved to be somewhwat difficult.  It seems that the sequencer is run after the compositor (despite their non-exclusivity in the Post Processing panel), so my idea to use an image strip in the sequencer for all the images that I already rendered didn't work&mdash;the render just copied the images into a new directory.  The Movie Clip node doesn't seem to accept an image strip as input, either, so that was not an option.  What I ended up doing was sequencing the animation to a movie file, then piping that into the Movie Clip node in the compositor. However, this required extra time, extra storage, and it rendered the default scene every frame before compositing, only to ignore the result.  Is there a way to use Blender's compositor either directly on an image sequence, or in conjunction with the video sequencer? Disable Tabbing in Firefox 3, Chrome 4 and IE8? Tabbed Browsing may be nice for reading news sites in one sitting, but I still think they are a usability nightmare if you need to keep the page open for a long time, e.g., for testing it while developing or as a reference for something.  The nice thing about the Windows Taskbar (before Windows 7 ) is that it's easy and natural to remember where things are. I can have 30 tabs in it, but because I know what each one is, I know where I have to click to open something - it's the most efficient way of working I've encountered so far.  Sadly, Tabbed Browsing completely breaks this efficiency because it is not possible to specifically click on a tab in the taskbar, I have to click on the browser, search the tab and then click it, which means at least 2 clicks.  Long story, short question: Is there an extension or setting to completely disable tabbing on Firefox 3, Chrome 4 and Internet Explorer 8 and have one Window/Taskbar entry for each open page? I know that in Chrome I can just drag a tab out of a Window to create a new one, but if there is a general way, that would be easier.  Edit: IE8 conveniently offers an option for that: Tools - Options - Tabs - Enable Tabbed Browsing. Objective-C Static Class Level variables I just uninstalled TeX Live 2016 and installed TeX Live 2017 and I noticed that the vertical alignment of author and title in any beamer presentation with Warsaw theme has been disrupted. In this example the author is JESTIN and the title is Beamer Intro. How can I vertical center them?  Moreover, I just found the same bug in the beamer guide obtained writing texdoc beamer in the command prompt, in the part of a warsaw presentation.    Here is my code:  \documentclass{beamer}  \usetheme{warsaw}  \title[Beamer Intro]{Beamer - Introduction to \LaTeX{} presentation making} \author[JESTIN]{Jestin Joy}  \begin{document}  \begin{frame}   \titlepage \end{frame}  \end{document} So the complex number z is given as   $z=1-cos(2\theta)-isin(2\theta)$  And the question is to find the argument of z in terms of $\theta$.   So, I used the formula for calculating the argument of a complex number:  $arg(z)=arctan (\frac{sin(2\theta)}{1-cos(2\theta)})$  $=arctan (\frac{2sin\theta cos\theta}{1-(1-2sin^2\theta)})$  $=arctan (\frac{2sin\theta cos\theta}{2sin^2\theta})$  $=arctan (\frac{cos\theta}{sin\theta})$  $=arctan (cot\theta)$  $=arctan (tan(\frac{\pi}{2}-\theta))$  $=\frac{\pi}{2}-\theta$  But apparently the answer is $\theta-\frac{\pi}{2}$.  Where might have I gone wrong?  Edit: the domain given in the question for $\theta$ was $0≤\theta≤\pi$ Transparent text cut out of background Suppose $f:[0,1] \to (0,\infty)$ is a Riemann integrable function. Prove that the integral of the function from $0$ to $1$ is strictly positive.   I have been trying to do this for awhile but I can't seem to get it. Here is my thought process: If the function is Riemann integrable, then its set of discontinuities has measure zero (Lebesgue). I am not sure how to connect this to the integral being positive How do I bind the tmux prefix to a Super? I find even Ctrl+b to be very emacs like but I understand the point. I'm wondering if I could bind it to a single keypress of a key I don't other wise use? namely Super_L (also known as the left windows key. for why I say Super_L start xev in a terminal and press that key) What does the tilde (~) mean at the end of a filename? What is the file with the ~ at the end of the filename for?  $ ls # aliased to add flags -rwxrwxr-x  1 durrantm  2741 May 16 09:28 strip_out_rspec_prep_cmds.sh~* drwxrwxr-x 13 durrantm  4096 May 16 14:21 ../ -rwxrwxr-x  1 durrantm  2221 May 16 14:58 strip_out_rspec_prep_cmds.sh*   This is not the same as .swp files which are there while editing.  The two files have quite a few differences and the newer file (no ~ at the end) has the most recent changes and those changes are not in the older (~) file.  Looks like I can delete it? C structure initialization? If I build a package from source how can I uninstall or remove completely? I used source code to build one package such as below:  ./configure --prefix=/usr --sysconfdir=/etc --localstatedir=/var --libexecdir=/usr/lib --with-package-name="Myplugin" --with-package-origin="http://www.ubuntu.org/" --enable-gtk-doc --disable-static make make install   But unfortunately, i discovered that its the latest version, and has lot of bugs, so i need to remove it/uninstall it. But how can i do so? I tried make clean; make uninstall but still i see it exist:  # pkg-config --list-all | grep Myplugin myplugin-.... $ ls /usr/lib/myplugin/libXYZ.so exist....   How do you remove this now? Merge some tab-delimited files Auto-run scripts security options