Inline ruby in :javascript haml tag?
Injecting variable values into javascript and HAML in RoR
Infinite sum of ideals I've been trying to prove that given a ring $R$ and a collection of ideals $\{I_{\beta}\}_{\beta \in B}$ in $R$, the set $$\sum_{\beta \in B} I_{\beta}=\{f_1+\cdots+f_r:f_j \in I_{\beta_j}, \mbox{ for some } I_{\beta_j}\}$$ is an ideal and is the smallest ideal containing $\cup_{\beta \in B} I_{\beta}$.  I've already proved when I only have two ideals, and so, using induction, I've seen it for finite sums. But I don't see how to generalise that to an arbitrary family of indexes (maybe infinite) $\beta$.   Could someone please give me a hand? Thank you. When using custom path style in a tikz graph the quotes label isn't printed Get the client IP address using PHP I will try to be as explanatory as possible with my question. Please also note that I have done my share of googling and I am looking for simple language preferable with some example so that I can get some insight in this subject.  My question is what is so special about $c$? Why only $c$. Its like chicken and egg puzzle for me. Does Einstein reached to $c$ observing light or does he got to light using some number which turned out equal to $c$.   Why is $c$ not relative. If something has zero rest mass like a photon why they only travel at $c$ in vacuum and not with $c+1$ or $c-1$? When is the completion of a ring a local ring ? Let $R$ be a commutative ring with unit and let $m$ be a maximal ideal of $R$. Are there known conditions on $R$ or $m$ such that the $m$-adic completion $\hat{R}$ of $R$ is a local ring.   Since the completion of a Noetherian local ring is again local, I'm primarily interested in cases where $R$ itself is not local.   An example is the polynomial ring $R=k[X_1,...,X_n]$ ($k$ a field) with $m=(X_1,...,X_n)$ where the power series ring $\hat{R}=k[[X_1,...,X_n]]$ is local with maximal ideal $(X_1,...,X_n)$. Formula for determinant of block matrix with commuting blocks On , I saw the following formula  $$\det\begin{bmatrix}A &amp; B\\ C &amp; D\end{bmatrix} = \det(AD-BC)$$  if $C$ and $D$ commute. Is this always true?   Or is there a good counter example for each $2 \times 2$ block matrices? breaking of output into new lines I know it's possible to match a word and then reverse the matches using other tools (e.g. grep -v). However, is it possible to match lines that do not contain a specific word, e.g. hede, using a regular expression?   Input:  hoho hihi haha hede   Code:  grep "&lt;Regex for 'doesn't contain hede'&gt;" input   Desired output:  hoho hihi haha There are a number of services that will scan a website for vulnerabilities and allow the display of a trustmark image if the site passes their tests.  This allegedly increases the level of trust a potential client feel toward the website and therefore makes them more likely to complete a purchase.    McAfee claims it has studies which show significant increases in sales. Should I take their word for it?  What sort of increase should I really expect, if any?  Are these types of services worth the prices they charge? I don't know how to solve $7^x-3^y=4$... I tried to see something $\pmod 7$ and $\pmod 3$ but it doesn't help at all. Can anyone give me some hints about it? What is a Windows Handle? I need to set the default home page for the entire domain via GPO. Where is the IE Home Page Policy located? I have a table that looks like this:  +----------------------------------------+ |Name                | kode      | jum   | +----------------------------------------+ | aman               |kode1      | 2     | | aman               |kode2      | 1     | | jhon               |kode1      | 4     | | amir               |kode2      | 4     | +--------------------+-----------+-------+   How can I make a view like this with MySQL?                      kode1    kode2     count aman                  2         1        3   jhon                  0         4        4 amir                  0         4        4 How do you change age settings on ROBLOX? How do you set your age settings on ROBLOX if you accidentally set to under 13? I accidentally put 2008 instead of 1998 in the sign up section. Is there any way to change this, as in settings, age settings are greyed out. No output from goroutine How do I rename a directory via the command line? I have got the directory /home/user/oldname and I want to rename it to /home/user/newname. How can I do this in a terminal? How to download a file using Selenium's WebDriver? Basically I want to at least check that a download-able file exists / download link works and preferably get stuff like the file size too. Here's an example: link = self.browser.find_element_by_link_text('link text') href = link.get_attribute('href') download = self.browser.get(href) print download  That fourth line prints &quot;None&quot;, presumably because I haven't manually clicked the Save button, and even if I had, I doubt WebDriver would be able to &quot;see&quot; the file. Any ideas? I'm using Firefox as my browser-under-test, and I understand that the file handling for downloads is somewhat browser and/or OS-specific. How do I remove macOS completely from my MacBook Air 2015 and install Windows 10 only after?  I have tried formatting my drive to GPT and tried booting a Windows Installation USB however I'm stuck at the installer not being able to find any drives. How is light affected by gravity? Light is clearly affected by gravity, just think about a black hole, but light supposedly has no mass and gravity only affects objects with mass.  On the other hand, if light does have mass then doesn't mass become infinitely larger the closer to the speed of light an object travels. So this would result in light have an infinite mass which is impossible.  Any explanations? Convert Shapefiles to GeoJSON? I'm trying to convert Shapefiles from the  website into a GeoJSON file for use with Google Maps API. I'm using QGIS to facilitate but I can't get the projection/coordinates right. So far I've tried Google Mercator (EPSG:900913) and WGS 84 (EPSG:4326) with no luck. I'm using the OpenLayers to verify results and it keeps placing Texas near the  Gulf of Guinea (0 lat, 0 lng).