I was thinking about this a short while ago, to expand what links onebox in SE chat.  Essentially, anything that has a valid &lt;meta name="description" /&gt; tag should be able to be one-boxed. The &lt;title&gt; could be used for the title of the box, and the meta description tag for the body. This could also (perhaps) be extended to the &lt;meta property="title"&gt; as well (defined by RDFa 1.1), though I suspect this is less common.  Optionally, chat could also support the  (&lt;og:meta&gt;) tags as well. Though these should only be used if the regular HTML &lt;meta&gt; tags cannot be used.
Oneboxing is a handy feature in chat for quickly previewing links, but the list of supported sites is very small, and occasionally boxes for sites such as Wikipedia can break and fetch any image/text.  Instead of having to request additional sites to be added to the onebox list (, , , , , and of course ), we could let the sites themselves handle the oneboxing with some &lt;meta&gt; tags, such as:  &lt;meta name="onebox-title" content="The Onebox Title"/&gt; &lt;meta name="onebox-image" content="/image.png"/&gt; &lt;meta name="onebox-summary" content="This is the summary for a site's onebox"/&gt;   Then when a link is placed on its own in chat, the oneboxing spider would look for these tags and, if they are found, show the appropriate data.  Support for these tags would certainly be bad (for lack of any real better term) at first, though most users of SO chat could easily add it to their personal / company's sites (should they be in such a position) and writing friendly suggestions to other sites to implement them isn't exactly a gargantuan effort.  This would also present an opportunity for currently oneboxed sites to set in stone what should be shown, such as each Wikipedia article setting the main image to be oneboxed instead of SO's spider picking one willy-nilly.  Finally, sites implementing these tags would lay the foundation for other sites and services to develop similar features to the onebox, without having to write per-site scrapers.
Detect if an outgoing call has been answered Cardinality of Irrational Numbers I know and I have proved more than once that the set of irrational numbers ($\mathbb{I}$) is uncountable, but now I'm given to solve this problem:   Show that $|\mathbb{I}|=|\mathbb{R}|$,  How can I do that?  Do I need to assume the Continuum Hypothesis in order to that statement to be true?  Thanks Was Hogwarts named such because of a connection to warthogs? Was Hogwarts named 'Hogwarts' because of a connection to warthogs?  Or was it named for hogs and warts separately, or something else entirely? How can I make a part of a texture glow? Allow users to put their e-mail in posts? Should I edit out the (thankfully obsfucated) e-mail address from this ?  Is this something we should allow on the site going forward?  I don't care about the "thank you" or "hello", but this might lead to an answer being sent by e-mail, which would mean it wouldn't be peer reviewed (for what that's worth), and the answer would be lost to the community. Is there a command to show the directory/file name when cat files?  For example: assume two files f1.txt and f2.txt are under ./tmp  ./tmp/f1.txt ./tmp/f2.txt    Then when I do cat ./tmp/*.txt, only the content of files will be shown. But how to firstly show the file name, then the content?, e.g.:   (The needed command):  ./tmp/f1.txt:    This is from f1.txt  and so on  ./tmp/f1.txt:  This is from f2.txt ...   Is there a command to do it? (There seems to be no option for 'cat' to show the file names) What is the rule to convert the 'mm' notation to the 'optical zoom' notation? I searched a bit and found this one:  optical zoom = maximum focal length / minimum focal length   For example a 18-55mm lens would have a 3x optical zoom, and a 18-200mm lens would have a 11x optical zoom. Is that right? Lowest voltage drop diode possible I am harvesting energy from an NFC device using a tuned antenna on my PCB. Though this method I am able to generate about 3.05V. I would like to charge a super capacitor using the power harvested from the NFC device. To do this I have  used the simple diode circuit provided  (and shown in Figure 1 below).  The problem I am facing is my circuit requires a minimum of 3V to operate within operating conditions, however with the added drop by typical diodes I believe there with be various situations where the generated voltage will drop below the required 3V. Are there any Diodes available which have ultra low voltage drops of less then 0.01V? and is that even possible?  Please note:   my system load will be &lt; 5mA  The 3.05V generated was without a diode in the circuit One may not always know the Type of an object at compile-time, but may need to create an instance of the Type.    How do you get a new object instance from a Type? Calculate the sum of inverse values of ${n\choose 0}, {n\choose 1}, ... {n\choose n}$ Calculate $$A={1\over {n\choose 0}}+ {1\over {n\choose 1}}+ ...+{1\over  {n\choose n}}$$  and  $$B={1\over {n\choose 0}}- {1\over {n\choose 1}}+ ...+{(-1)^n\over  {n\choose n}}$$     My idea for $A$ is some probabilistic reasoning. Color the sets $$\{\}, \{1\}, \{1,2\}, \{1,2,3\},...\{1,2,...,n\}$$ and ask our self what is the probability that I choose colored set among all sets. Clearly this is exactly ${n+1\over 2^n}$ and on the other side it is $A$:  probability that I take empty set is ${1\over {n\choose 0}}$,   probability that I take colored set with 1 element is ${1\over {n\choose 1}}$  probability that I take colored set with 2 elements is ${1\over {n\choose 2}}$  and so on ...   So $A ={n+1\over 2^n}$. But I have no idea how to attack $B$. I'm reading Galois Theory by Steven H. Weintraub (second edition), and finding that I'm at least somewhat short on the prerequisites. However the following proof looks wrong to me - am I misunderstanding something, or is it actually an incorrect proof?  Lemma 2.2.3. Let $F$ be a field and $R$ an integral domain that is a finite-dimensional $F$-vector space. Then $R$ is a field. Proof. We need to show that any nonzero $r \in R$ has an inverse. Consider $\{1, r, r^2, \cdots\}$. This is an infinite set of elements of $R$, and by hypothesis $R$ is finite dimensional as an $F$-vector space, so this set is linearly dependent. Hence $\sum_{i=0}^n{c_i r^i} = 0$ for some $n$ and some $c_i \in F$ not all zero.  It then goes on to show, given the above, that we can derive an inverse for $r$. However, if I consider examples like $r = 2 \in Q[\sqrt{2}]$, $r = \sqrt{2} \in Q[\sqrt{2}]$ or $r = 2 \in Q[X]/{&lt;X^2&gt;}$, the set $\{1, r, r^2, ...\}$ doesn't look linearly dependent to me. I do believe the lemma is true (and might even be able to prove it), but this does not look like a correct proof to me. Am I missing something? [Edit] Well yes, I am. Somehow I had managed to discount the possibility of any $c_i$ being negative, despite repeatedly looking at each fragment of the quoted text in an attempt to find what I might be misunderstanding. Prime ideal and nilpotent elements Adding "noise" to overlapping X,Y coordinates so no longer in EXACT same place? I have a series of points representing animal observations. Many of them overlap, having the exact same coordinates, and this is causing me trouble when I want to run some analytical tools which requite no identical points. I was wondering if there's any tool that can add some "noise" to the coordinates, that's to say, adding some random decimal values at the end in order to obtain slightly different coordinates which are still close enough in space so as to not really modify the observation. I've heard about such a tool, but I can't find it, at least in ArcGis 10. Maybe there's another software that can do it? Thanks! Symmetric Matrix , Eigenvectors are not orthogonal to the same eigenvalue. I know that the symmetric matrix has orthogonal eigenvectors corresponding eigenvalues. Also, the eigenvectors from the same eigenvalue are linearly independent.  I need an example of symmetric matrix such that the eigenvectors from the same eigenvalue are not orthogonal.  Also, I know that the eigenvalues of the symmetric matrix are real. But , this statement true iff the entries are real numbers.Right? Since the matrix 2x2 $$A=\begin{bmatrix} 1 &amp;i \\  i &amp;1  \end{bmatrix}$$  has non real eigenvalues "In a party people shake hands with one another" Application of Kolmogorov's Zero-One Law Most of the books I read, they only state some examples of tail events. One of them is  $[\sum_n X_n \ converges]$. My main problem is to show that this is indeed a tail event. Let us view our deleted comments 8.4 - Use entity browser in a module block from in same way as I would in a custom block High-Swing Cascode Current Mirror I am currently dealing with current mirrors and came across the circuit shown below, a High-Swing Cascode Current Mirror. I read that this implementation, as the name suggests, has the advantage of a high voltage headroom, since the minimum potential at the drain terminal of M4 is: $$ V_{D4\_min}=V_{DS4}+V_{DS2}=(V_{GS4}-V_{TH})+(V_{GS2}-V_{TH}) $$ So the drain potential at M4 only needs to be twice the overdrive voltage, in case of same transistor dimensions, in order to hold M2 and M4 in saturation. But cannot this be said for many other cascode current mirrors, since that behaviour simply occurs by "stacking" together two transistors (M2 and M4)? Additionally, why is there a connection from the gate of M1 to the drain of M3? I have a hard time understanding whats going on in this circuit, help is greatly appreciated.    EDIT: A bias voltage source is setting the potential at the gate of M3/4. Sorry its not shown in the circuit.  EDIT 2: I just read that the mentioned bias voltage is implemented by a MOSFET in diode configuration, . For further discussion lets call it M5. A concrete example of involution in group theory I am reading the textbook "Introduction to Modern Algebra, Joyce 2017" and in the Cyclic groups and subgroups section, there is a following sentence about involution.     An involution $a$ is an element of a group which is its own inverse, $a^{-1} = a$. Clearly, the order of an involution $a$ is $2$ unless $a = 1$, in which case the order of $a$ is $1$.    I was trying to come up with a concrete example, but I am having difficulties. Maybe when $a = \frac{1}{2}, \frac{1}{2}^2 = 1$? I also searched the  for a concrete example, but wasn't able to find anything.  Can someone provide an example with numbers for me please? I want to understand why the author writes "clearly" that the order of an involution $a$ is $2$. Thank you