How can I figure out which is my file manager system?
How to find out the default file manager in the terminal?
Installing VMware on 18.04: Failed to build vmmon Should flawed questions be closed immediately? Is spacetime discrete or continuous? Is the spacetime continuous or discrete? Or better, is the 4-dimensional spacetime of general-relativity discrete or continuous? What if we consider additional dimensions like string theory hypothesizes? Are those compact additional dimensions discrete or continuous?   Are there experimental evidences of continuity/discreteness?  When particles move inside space do they occupy spacetime by little chunks? What would imply if spacetime is discrete on continuous theories?  I've found little information on the web and books.  Probably my question is ill-posed and I apologize for this. Every Artinian ring is isomorphic to a direct product of Artinian local rings $\sum \cos$ when angles are in arithmetic progression Possible Duplicate:          Prove $$\cos(\alpha) + \cos(\alpha + \beta) + \cos(\alpha + 2\beta) + \dots + \cos[\alpha + (n-1)\beta] = \frac{\cos(\alpha + \frac{n-1}{2}\beta) \cdot \sin\frac{n\beta}{2}}{\sin\frac{\beta}{2}} $$ solving third-order nonlinear ordinary differential equation The definition for marker below is from tcolorbox.doc.s_main.sty. With earlier versions of Texlive (and tcolorbox), this worked fine, but with updated Texlive, it does not.  \documentclass{article} \usepackage{xcolor,tikz,tcolorbox} \usetikzlibrary{shadows} \tcbuselibrary{skins,hooks} \makeatletter % from tcolorbox.doc.s_main.sty \newtcolorbox{marker}[1][]{enhanced,   before skip=2mm,after skip=3mm,   boxrule=0.4pt,left=5mm,right=2mm,top=1mm,bottom=1mm,   colback=yellow!50,   colframe=yellow!20!black,   sharp corners,rounded corners=southeast,arc is angular,arc=3mm,   underlay={%     \path[fill=tcbcol@back!80!black] ([yshift=3mm]interior.south east)--++(-0.4,-0.1)--++(0.1,-0.2);     \path[draw=tcbcol@frame,shorten &lt;=-0.05mm,shorten &gt;=-0.05mm] ([yshift=3mm]interior.south east)--++(-0.4,-0.1)--++(0.1,-0.2);     \path[fill=yellow!50!black,draw=none] (interior.south west) rectangle node[white]{\Huge\bfseries !} ([xshift=4mm]interior.north west);     },   drop fuzzy shadow,#1} \makeatother   \begin{document} \begin{marker}   Hylo! \end{marker}  \end{document}   This gives the following error  ! Package xcolor Error: Undefined color `tcbcol@back'.  See the xcolor package documentation for explanation. Type  H &lt;return&gt;  for immediate help.  ...                                                l.34 \end{marker}  ?   Why are tcbcol@back and tcbcol@frame undefined if they work in the code for the package's documentation? Alternatively, what are the correct names for the colours which were tcbcol@back and tcbcol@frame?  My version of tcolorbox is 2019-09-19. formal proof from calulus Given $f:R \to R$, $f$ is differentiable on $R$ and $\lim_{x \to \infty}(f(x)-f(-x))=0$. I need to show that there is $x_0 \in R$ such that $f'(x_0)=0$  I am trying to prove it by contradiction .... so i assume there is no $x_0 \in R$ such that  $f'(x_0)=0$ this means this function is strictly monotonic because the derivative "respects" the mean value theorem so it cannot be negative and positive without passing a zero value ....  (from what i understand the derivative function of a continuous/differentiable functions isn't necessarily continuous but it still respect the mean value theorem i think it's called darboux's theorem )  now from $\lim_{x \to \infty}(f(x)-f(-x))=0$ ,we get $\lim_{x \to \infty}f(x)=\lim_{x \to \infty}f(-x)$  now the last step is the contradiction its very intuitive and even maybe obvious that we can't get $\lim_{x \to \infty}f(x)=\lim_{x \to \infty}f(-x)$ for strictly monotonic function but i cant think of a formal way to prove it . I am on a Mac with MacTex 2020 and ran into a strange problem with Biber. Working on a document all was fine, I did not change the bibliography (says my git) and only fixing typos (not even adding cites) and suddenly latexmk stopped working after a Biber run, while that looked like  INFO - This is Biber 2.14 INFO - Logfile is 'doc.blg' INFO - Reading 'doc.bcf' INFO - Found 31 citekeys in bib section 0 INFO - Processing section 0 INFO - Globbing data source 'literature.bib' INFO - Globbed data source 'literature.bib' to literature.bib INFO - Looking for bibtex format file 'literature.bib' for section 0 INFO - LaTeX decoding ... INFO - Found BibTeX data source 'literature.bib'   so harmless in my view. Then with --debug I additionally get in the end.  INFO - LaTeX decoding ... warning: overriding existing definition of macro "jun" warning: overriding existing definition of macro "jul" warning: overriding existing definition of macro "sep" warning: overriding existing definition of macro "jan" [...] warning: overriding existing definition of macro "nov" INFO - Found BibTeX data source 'literature.bib' Unicode::UCD: failed to find unicore/version in /var/folders/hm/gt63cn0j2r7bwbzw7c1hww1r0000gn/T/par-626572676d616e6e/cache-2f8a664c3c933a44d096bcc8d018a5e92bced897/inc/lib /var/folders/hm/gt63cn0j2r7bwbzw7c1hww1r0000gn/T/par-626572676d616e6e/cache-2f8a664c3c933a44d096bcc8d018a5e92bced897/inc CODE(0x7fd026aeb5a8) CODE(0x7fd026aebb90) at /var/folders/hm/gt63cn0j2r7bwbzw7c1hww1r0000gn/T/par-626572676d616e6e/cache-2f8a664c3c933a44d096bcc8d018a5e92bced897/inc/lib/Biber/Input/file/bibtex.pm line 1011.   It seems unrelated to the library itself since deleting a few entries (going through deleting one half, then the other), the problem persists. It does not happen for an empty literature, but as soon as a first entry is added (just author/journal/title/year/volume/pages - no utf8-only chars) this error message appears.  what does this last error message mean?  How can I solve this? How to search for only folders in Windows 7 instead of folders AND files I've had some issues with the new search function in Windows 7. The Search in Windows XP was packed with so many more options. The only option I can access now are Date Modified and Size.  Any pointers to how to get more options in the Windows 7 Search, or links to external programs that can make my life easier? Compute $E(X\mid X+Y)$ for independent random variables $X$ and $Y$ with standard exponential distributions Being $X$ and $Y$ independent random variables distributed as $\mathrm{Exponential}(1)$ and let $T=X+Y$ Calculate $E(X|T)$.  This is my attempt at solving this:  Being $Z=\sum_{i=1}^{n}P_{i}$ where $P_{i}$~$\mathrm{Exp}(\lambda)$ then using it's MFG you have that $$M_{P_i}(t)=\frac{\lambda}{\lambda-t}$$ then $$M_{Z}(t)=M_{\sum{P_{i}}}(t)=(M_{P_{1}})...(M_{P_{n}})=(\frac{\lambda}{\lambda-t})^n$$ with this being the MFG of a $\mathrm{Gamma}$ distribution with parameters $(n,\lambda)$  With this result is easy to see that $T$~$\mathrm{Gamma}(2,1)$  Now $E[X|T]=\int xf_{X|T}(x|t)dx$  Then using Bayes' theorem we can make $$f_{X|T}(x|t)=\frac{f_{T|X}(t|x)f_{X}(x)}{f_{T}(t)}$$ then $$f_{T|X}(t|x)=Pr(T=t|X=x)$$ $$=Pr(X+Y=t|X=x)$$ $$=Pr(x+Y=t|X=x)$$ $$=Pr(Y=t-x)=f_{Y}(t-x)$$  Using this result we can now rearrenge $$f_{X|T}(x|t)=\frac{f_{Y}(t-x)f_{X}(x)}{f_{T}(t)}$$ $$=\frac{e^{-(t-x)}.e^{-x}}{\frac{te^{-t}}{\Gamma(2)}}$$ $$=\frac{1}{t}$$ then $$E[X|T]=\int (x)(\frac{1}{t})dx$$  And this where I got stuck because $1_{x\epsilon(0,\infty})$, I made this explanation step-by-step hoping that someone can se easily check where I went wrong. I would aprecciate a step-by-step answer, thanks. How does the linux kernel know device major and minor numbers? As far as I know, the kernel detects hardware, adds information to sysfs creates a device in /dev and then generates a udev event. My question is, do device drivers do all of this or it is the kernel itself? If drivers do it, then they would know the device major and minor number to create the file in devtmps.   I also understand (maybe wrongly) that it is udev who calls modprobe to load the drivers that handle a device.   I was told that they do so with the contents of the MODALIAS uevent environment variable, thus loading all modules whose aliases match this string (the correct driver). In short: what are the steps of hardware detection in linux and WHO performs each step: the kernel itself, the driver inside the kernel or udev in userspace. Thanks. The difference between "Older" and "Elder" What is the difference between "Older" and "Elder" ?  And are they interchangeable ? Do Nigerian citizens need a transit visa for Brazil? Do I need a transit visa in Brazil on the way to Ecuador. I am a Nigerian national.   I am travelling to ecuador and I was asked to get a Brazilian transit visa as I am to board another airline from Sao Paulo. Ppening an HTML file on localhost in XAMMP/apache 2.2 using subdirectories under htdocs I have a site directory for html (dreamweaver CSS3) with lots of subdirectories that contain HTML files for a number of drop down menus. They work fine where they are, but they all have menus that are JavaScript and could be kept in a separate file. So, I want to use Include. I don't want to have to FTP my files to HostGator every time I want to test the includes. I want to have this on my local machine. So, I am attempting for the first time to setup XAMMP and then run my html files (site) on localhost, so I can see what they look like before ftping everything to HostGator and putting it live.  I tried copying the main site folder to htdocs, and then copying the path to the file I want to run in front of the localhost in Firefox, but it gave me file not found:   Do I have too many subdirectories? Why isn't the file being found? It is there.  Tried this too:   No go. How to remove the whitespace BEFORE itemize/enumerate? I'm somewhat of a LaTeX noob, and this is driving me completely nuts.  When I type  \documentclass{article} \usepackage{enumitem}  \begin{document}     Some text     \begin{itemize}[noitemsep]         \item Item 1         \item Item 2         \item Item 3     \end{itemize} \end{document}   I don't want the space which appears in between the text "Some text" and the itemization to be there:    When I search around on Google all I see is tons of long, complicated advice on this site, StackOverflow, forums, etc. on how to not fix the problem ("parskip is evil", etc.), or tons of vague/confusing answers on what package to look at, with no actual example for me to learn from.  So while this question is already asked many times, I have never found a single concrete answer to this question.    The question couldn't be simpler: How do I "properly" get rid of this extra space? Is a function defined at a single point continuous? Is a function defined at a single point continuous?  For example $f:\{0\}\to\{0\}$ defined by $f(x)=\sqrt{x}+\sqrt{-x}$ is a sum of two continuous functions and is therefore continuous, however for $f$ to be continuous, it has to have the limit $\lim\limits_{x_0\to x}f(x_0)=f(x)$ but it dosen't seem to have that limit. Boolean Modifiers not working normally When using a Boolean modifier on an object, the "Operation" choices (Difference, Union, Intersect) are all not working normally. Choosing "Union" makes it do the effect of "Intersect" and "Difference" makes it do what "Intersect" is supposed to do. What's the deal here?   This is happening with following a simple tutorial. It's a simple primitive cube and primitive cylinder. No normals or doubles problems.   My specs are:  Macbook Pro 13" Retina early 2015 512GB i7 with 16gb RAM upgrade OS-X version 10.11.4 Is there a way to load my own custom CSS or Javascript while using a browser?  When I'm accessing a website or developing a website I want to load my own custom scripts from my computer. I know this can be done by Firebug or Chrome's developer toolbar, but after you refresh your browser your changes will be cleared too. This is exactly what I'm looking for adding CSS and Javascript, but I wish it has an option where you temporarily save your changes locally. Or it has an option to load external CSS or JS files.   Purpose:   When I'm developing the frontend, sometimes it's convenient for me using Chrome's developer toolbar or Firefox's Firebug to change or tweak CSS properties because I can then see the changes in real time without refreshing. One problem I see is that every time I refresh my browser, my changes also get reset. Now I wish there were an option where I could save my changes locally or load my own external .css file or .js file. I want to customize how some websites look when viewed locally, e.g., accessing a blog that has too many ads. I want to apply CSS properties to hide the junk.   Browsers I use often:   Google Chrome (for development: Built-in Dev Toolbar) Mozilla Firefox (for development: Firebug) For example:   For an MVC architecture, should I prefer Ruby on Rails or PHP [closed] Gmail: What is a jQuery selector for incoming mail senders only? How to work with highly compressed and nested CSS in general? [closed]   Better to convert to   [closed] For an MVC architecture, should I prefer Ruby on Rails or PHP [closed] Gmail: What is a jQuery selector for incoming mail senders only? How to work with highly compressed and nested CSS in general?   I should first read the title and sometimes open the question to understand if the question is closed.  I think the [closed] mark  should be at the beginning of the title, not in the end, where I won't ever be if the title is long.  Also coloring will be a good improvement (via @Shadow Wizard).