Recently, when fighting wizards and spell casters, I've taken to a little trick of using my Action to Hold Action. With this Held Action I have readied a  with a trigger of a spell being cast. Basically a poor man's counter spell.  As far as I can see, that's within the remit of holding an action. Great!  It got me thinking though, that if a wizard casts  as their reaction, but I have a Dispel Magic ready on a trigger of "if I see a Counterspell" does one trump the other?
When playing as a spellcaster, is it valid the use of the Ready action to prepare Dispel Magic to counter a spell cast by an opponent? In the same vein, when declaring said action, do I have to specify which spell slot I will use when Readying the Dispel Magic spell? If that is the case, does this tactic nullify an opponent's spell? I get the impression that this is basically turning Dispel Magic into a spell with a casting time of &quot;1 reaction&quot;. Is my reading of the rules accurate?
What is "step size" in LASSO regression? If $p$ and $q = 2p + 1$ are both odd primes, show that $-4$ and $2(-1)^{(1/2)(p-1)}$ are both primitive roots modulo $q$. If $p$ and $q = 2p + 1$ are both odd primes, show that $-4$ and $2(-1)^{(1/2)(p-1)}$ are both primitive roots modulo $q$.   I cannot get heads nor tails of how to even start this let alone finish it Optional argument to \item Journal vs conference publications when looking for a job in in computer science I'm currently a post doc in theoretical computer science and I have a double digit number of conference publications, about half of which are at so called "tier 1" conferences (SODA,STOC,...). Unfortunately I only have 1 journal publication so far, mainly due to coauthors dragging their feet.   Will the lack of journal publications have a great impact when applying for a faculty job in cs-theory at some point, and is it advisable to try to up this number before applying? Or is this fully compensated by having sufficiently many conference papers? Example of a relation that is symmetric and transitive, but not reflexive Can you give an example of a relation that is symmetric and transitive, but not reflexive?   By definition,   $R$, a relation in a set $X$, is reflexive if and only if $\forall x\in X$, $x\,R\,x$.  $R$ is symmetric if and only if $\forall x, y\in X$,  $x\,R\,y\implies y\,R\,x$. $R$ is transitive if and only if $\forall x, y, z\in X$, $x\,R\,y\land y\,R\,z\implies x\,R\,z$.    I can give a relation $\leqslant$, in a set of real numbers, as an example of reflexive and transitive, but not symmetric. But I can't think of a relation that is symmetric and transitive, but not reflexive. Login required moving to Super User on iPad When moving around the sites on Stack Exchange using Safari on my iPad (not the Stack Exchange App), I am fine when moving to any site other than SuperUser.  When logged in, I can switch sites and stay logged in, but when I switch to Super User I need to log in again. If I choose not to log in and switch to another site, I am logged in there. Is there a problem with the login handling for Super User? If it helps, I log in with a Stack Exchange account, not through Facebook or Google. Update After getting fed up with the problem, I took the advice given in the answer below which was to use Chrome, and the problem still exists. The same goes for Firefox. Have I missed something?  As you can see from the screenshots below, there are no cookie settings to be found. Chrome for iOS settings page  Privacy settings page  Content settings page  Google app settings page When does SQLiteOpenHelper onCreate() / onUpgrade() run? jQuery .on function for future elements, as .live is deprecated How can I play mp3 files or videos? What is $48\div2(9+3)$? There is a huge debate on the internet on the value of $48\div2(9+3)$. I believe the answer $2$ as I believe it is part of the bracket operation in BEDMAS.  yields the same answer. I also believe that if $48\div2\times(9+3)$ was asked it would be $288$ which Mathway agrees with as well. However,  says it is $288$ either way. A friend of mine (who is better at math) told me that there is no such thing as 'implicit multiplication', only shorthand so that is in fact done after the division (going left to right, not necessarily because division occurs before multiplication. But he didn't explicitly give a reason) What is the answer and why? Python and regular expression with Unicode biblatex in a nutshell (for beginners) How to lazy load images in ListView in Android I am using a ListView to display some images and captions associated with those images. I am getting the images from the Internet. Is there a way to lazy load images so while the text displays, the UI is not blocked and images are displayed as they are downloaded?   The total number of images is not fixed. What is "my guy syndrome" and how do I handle it? Explanation of method for showing that $\frac{0}{0}$ is undefined (This was asked due to the comments and downvotes on this  answer. I am not that good at maths, so was wondering if I had made any basic mistakes)  Ignoring limits, I would like to know if this is a valid explanation for why $\frac00$ is undefined:     $x = \frac00$    $x \cdot 0 = 0$        Hence There are an infinite number of values for $x$ as anything multiplied by $0$ is $0$.   However, it seems to have got comments, with two general themes.  Once is that you lose the values of $x$ by multiplying by $0$.  The other is that the last line is:      $x \cdot 0 = \frac00 \cdot 0$   as it involves a division by $0$.  Is there any merit to either argument? More to the point, are there any major flaws in my explanation and is there a better way of showing why $\frac00$ is undefined? What is the difference between apt and apt-get? supervisor field on the page of the title with Beamer I am editing a presentation of a research project, I am wondering if there is a field for "supervisor" on the page of the title, for instance \supervisor(which actually does not work)... If not, where do people conventionally add it? Attempting official deploy process with single sandbox may reset/remove all existing work? Why would Voldemort spare Lily? In one of Harry's dementor-induced flashbacks, he presumably hears his mother protesting against Voldemort:  Harry was falling again through thick white fog, and his mother’s voice was louder than ever, echoing inside his head – ‘Not Harry! Not Harry! Please – I’ll do anything –’ ‘Stand aside – stand aside, girl –’ ‘Harry!’  Voldemort tells her to stand aside - why did he not just kill her? When exactly does tmpwatch clear out files I place in /tmp?