jQuery - How to show/hide multiple DIVs with child DIVs
How do I hide a parent div if the child div doesn't contain an  tag?
Better extensible arrows Norm and unit sphere In classical logic, why is $(p\Rightarrow q)$ True if $p$ is False and $q$ is True? Cannot update grub with parameters on live USB I have booted from a live USB ("Try Ubuntu"), that also has a persistent option set (I used  to create one) to do some tests for .  I'm trying to test  (like ) by doing this  sudo nano /etc/default/grub sudo update-grub   The problem is that that last command gives me this:  /usr/sbin/grub-probe: error: failed to get canonical path of /cow.   It looks like /cow is the file-system that is mounted on /, according to:  :~# df Filesystem     1K-blocks    Used Available Use% Mounted on /cow             4056896 2840204   1007284  74% / udev             1525912       4   1525908   1% /dev tmpfs             613768     844    612924   1% /run ....   Is there a way for me to run update-grub? Let $\pi : \widetilde{X} \longrightarrow X$ be the blow up morphism of $X$ a long of $Y \subset X$, with exceptional divisor $E$ and $\text{dim}Y &gt; 0$,   where $X$ and $Y$ are smooth projectives schemes.   For an answer to a question asked here in the forum (), Blowing up and direct image of line bundle), we have: $$\pi_{*}\mathcal{O}_{\widetilde{X}}(-E) = I_{Y/X} \tag{$**$}$$ here $I_{_{Y/X}}$ denotes the ideal sheaf of $Y$.  $(**)$ was obtained through the following exact sequence: $$0 \longrightarrow \mathcal{O}_{\widetilde{X}}(-E) \longrightarrow \mathcal{O}_{\widetilde{X}} \longrightarrow \mathcal{O}_{E} \longrightarrow  0$$  My doubt is: How to find $\pi_{*}\mathcal{O}_{\widetilde{X}}(-nE)$ for $n \geq 0$? What if $n &lt; 0 $?  Thank you. Uniform convergence of $\sum (-1)^nf_n(x)$ on $[0,1]$ where $f_n(x)=x^n(1-x)$. Let $f_n(x) = x^n(1-x)$ and $\sum (-1)^nf_n(x)$.  I showed that this series point wise.  Case1) $x=1$ $$ f_n(1)=0 \, , \sum{(-1)^nf_n(1)} = 0 $$ Case2) $x\neq 1$ $$|f_n(x)| \leq |x|^n$$ since $$\sum |x|^n$$ converges, By abosultely convergese test $\sum (-1)f_n(x)$ converges.  I want to show that this series uniformly converges on $[0,1]$. Convert a matrix to a 1 dimensional array Group of even order contains an element of order 2 Suppose $A,B,C$ are sets. Prove that $A\mathbin\triangle B\subseteq C \iff A\cup C=B\cup C$. Suppose $A,B,C$ are sets.  Prove that $A\mathbin\triangle B\subseteq C \iff A\cup C=B\cup C$.  I proved that for $x\in A\setminus B$, $x\in A\cup C$ and for $x\in B\setminus A$, $x\in B\cup C$. How do I show that $A\cup C=B\cup C$, and that $A\mathbin\triangle B\subseteq C \iff A\cup C=B\cup C$? I have noticed that guest quarters on the Enterprise D have fruit bowls on their tables.  A prominent instance is the fruit bowl in Berlinghoff Rasmussen's quarters in "".  The first thing that Rasmussen does when Data takes him to his guest quarters is take a piece of fruit and shove it in his pocket.  Who replicates fruit for these fruit bowls before guests arrive?  More generally, who removes unused fruit and tidies quarters after guests leave?  Is there a ship hospitality staff, perhaps including Guinan's wait staff in Ten Forward? I have a bunch of Spring beans which are picked up from the classpath via annotations, e.g.  @Repository("personDao") public class PersonDaoImpl extends AbstractDaoImpl implements PersonDao {     // Implementation omitted }   In the Spring XML file, there's a  defined:  &lt;bean id="propertyConfigurer"    class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"&gt;     &lt;property name="location" value="/WEB-INF/app.properties" /&gt; &lt;/bean&gt;    I want to inject one of the properties from app.properites into the bean shown above. I can't simply do something like   &lt;bean class="com.example.PersonDaoImpl"&gt;     &lt;property name="maxResults" value="${results.max}"/&gt; &lt;/bean&gt;   Because PersonDaoImpl does not feature in the Spring XML file (it is picked up from the classpath via annotations). I've got as far as the following:  @Repository("personDao") public class PersonDaoImpl extends AbstractDaoImpl implements PersonDao {      @Resource(name = "propertyConfigurer")     protected void setProperties(PropertyPlaceholderConfigurer ppc) {     // Now how do I access results.max?      } }   But it's not clear to me how I access the property I'm interested in from ppc? How to do relative imports in Python? Imagine this directory structure:  app/    __init__.py    sub1/       __init__.py       mod1.py    sub2/       __init__.py       mod2.py   I'm coding mod1, and I need to import something from mod2. How should I do it?    I tried from ..sub2 import mod2 but I'm getting an "Attempted relative import in non-package".  I googled around but found only "sys.path manipulation" hacks. Isn't there a clean way?      Edit: all my __init__.py's are currently empty    Edit2: I'm trying to do this because sub2 contains classes that are shared across sub packages (sub1, subX, etc.).  Edit3: The behaviour I'm looking for is the same as described in  (thanks John B) I don't want to watch the prisoner cart ride to the execution: is it possible to skip this?   If so, how? Can I replace the intro movie file by some empty video? How do question bookmarks work? What does bookmarking a question mean? How do you bookmark a question? Do users get updates on their bookmarked questions? Are my bookmarks publicly visible? How do you see your own bookmarks? How do you see other users' bookmarks? How do you see which users have bookmarked a particular question? What impact does the bookmark system have on the voting system? Can I &quot;un-bookmark&quot; a question? Can I search within my bookmarks? "You just can't" vs. "you can't just " I'm a bit confused about this. Which expression is correct?     You can't just do that.    or      You just can't do that.   I'm trying to say:     You can't just bash an ideology because of what someone has said/done. Purely "algebraic" proof of Young's Inequality states that if $a, b \geq 0$, $p, q &gt; 0$, and $\frac{1}{p} + \frac{1}{q} = 1$, then $$ab\leq \frac{a^p}{p} + \frac{b^q}{q}$$ (with equality only when $a^p = b^q$).  Back when I was in my first course in real analysis, I was assigned this as homework, but I couldn't figure it out.  I kept trying to manipulate the expressions algebraically, and I couldn't get anywhere.  But every proof that I've seen since uses calculus in some way to prove this.  For example, a common proof is based on this  and integration.  The proof on Wikipedia uses the fact that $\log$ is concave, which I believe requires the analytic definition of the logarithm to prove (correct me if I'm wrong).  Can this be proven using just algebraic manipulations?  I know that that is a somewhat vague question, because "algebraic" is not well-defined, but I'm not sure how to make it more rigorous. But for example, the proof when $p = q = 2$ is something I would consider to be "purely algebraic":  $$0 \leq (a - b)^2 = a^2 + b^2 - 2ab,$$ so $$ab \leq \frac{a^2}{2} + \frac{b^2}{2}.$$ Why is Newton's method not widely used in machine learning? This is something that has been bugging me for a while, and I couldn't find any satisfactory answers online, so here goes:  After reviewing a set of lectures on convex optimization, Newton's method seems to be a far superior algorithm than gradient descent to find globally optimal solutions, because Newton's method can provide a guarantee for its solution, it's affine invariant, and most of all it converges in far fewer steps. Why is second-order optimization algorithms, such as Newton's method not as widely used as stochastic gradient descent in machine learning problems? This should be a fairly trivial problem. I'm trying to open an ofstream using a std::string (or std::wstring) and having problems getting this to work without a messy conversion.  std::string path = ".../file.txt";  ofstream output;  output.open(path);   Ideally I don't want to have to convert this by hand or involve c-style char pointers if there's a nicer way of doing this? Wikipedia lists the following pseudocode for HMAC:  function hmac (key, message)     if (length(key) &gt; blocksize) then         key = hash(key) // keys longer than blocksize are shortened     end if     if (length(key) &lt; blocksize) then         // keys shorter than blocksize are zero-padded ('∥' is concatenation)          key = key ∥ [0x00 * (blocksize - length(key))]      end if      // Where blocksize is that of the underlying hash function        o_key_pad = [0x5c * blocksize] ⊕ key      // Where ⊕ is exclusive or (XOR)     i_key_pad = [0x36 * blocksize] ⊕ key       // Where '∥' is concatenation        return hash(o_key_pad ∥ hash(i_key_pad ∥ message))  end function   Why are they there?  How were they chosen?  It seems to me that  $hash(key + hash(message))$ (where + is concatenation) would suffice.    Obviously I'm missing something.  What is it? Is there a way to give a profile a different default list view then "Recently Viewed" in Lightning?