When I want to talk about creating a structural model of a building or bridge, should I say modelling the structure or modeling the structure?
Possible Duplicate:          If I am using the word model in the context of financial models and the UK, then which of these words should I use? Also, are there any key difference in the meanings of the two?
Isomorphism equivalence implies fundamental group is abelian Examples of involutions on $\mathbb{R}$ Just recently I read up something about involutions (functions $f: A \rightarrow A$ such that $f(f(x))=x$, for all $x$ in the domain of $f$), and was wondering how many (if there is a small set of general functions) such involutions exist for $A = \mathbb{R}$, or maybe $A = \mathbb{R} - S$, where S is some set of points that would make the involution work if they were left out of $A$. In general I'm interested in real functions that are involutions, continuous or otherwise.  There were some examples I found , but any more would be certainly very interesting! Difference between decimal, float and double in .NET? What is the difference between decimal, float and double in .NET?  When would someone use one of these? When $z\neq 0$, $\arg z$ is defined to be the set $\{\theta \in \mathbb{R} : z=|z|e^{i\theta}\}$.  What if $z=0$? Usually does one leave the argument of $0$ undefined? Or is $\arg 0 = \mathbb{R}$? Why doesn't Doctor Strange remove the Infinity Gauntlet from Thanos? Doctor Strange seemingly has the ability to open portals wherever he wants. We see at the beginning of Infinity War what happens when he closes a portal and someone isn't fully through it.  Is there any reason why he can't open a portal around the left-elbow of Thanos, and then close it?  I realize that Thanos probably wouldn't allow this to happen normally,      but when he is mostly asleep, and Tony and Spider-Man are pulling on the gauntlet, Doctor Strange has ample opportunity, and plenty of space to just sever Thanos' arm.   Why doesn't he? What does "more buyers than sellers" in technical analysis of stocks actually mean? I often hear/read technical analysts looking at volume and price action on a chart and claiming that there are "more buyers than sellers" or vice versa.  Since every trade requires a buyer and a seller, how can volume/price signify more of one than the other?  What does that actually mean?  When I hear that there are "more buyers," I get the impression they actually mean more "professional" or "institutional" buyers, but I could just be imagining that meaning.  But wouldn't this "more buyers" situation actually represent a smaller number of large buyers placing multiple orders? (and those orders would be matched by a larger number of smaller investors on the other side of the trade?)  Maybe I have my assumptions backwards and "more buyers" is what they say when they actually mean "more retail buyers and less institutional buyers"?  Or maybe the expression has nothing to do with number of buyers/sellers at all and is just some arbitrary technical analysis situation?  What situation is it that they're trying to describe?  If the "smart money" traders had placed larger orders, then there would have to be equally large sellers on the other side of that large trade, right?  I know trades often get broken up, but if the trades had been broken up it would be equivalent to "large traders placing multiple orders" scenario described above.  If the trades were not broken up, then there would not be an imbalance in the "number" of "smart" vs. retail buyers/sellers, right?  UPDATE/EDIT: I usually see this stated in reference to technical indicators such as RSI.  I don't typically hear people saying "there are more buyers than sellers" in the situations you guys are describing with more unfilled orders on one side of the (potential) trade (though that would make more sense if that was what they were talking about).  See for example: $\forall$ At the beginning or at the end? I have a set of real numbers $x_1, x_2, \ldots, x_n$ and two functions $f:\mathbb{R} \rightarrow \mathbb{R}$ and $g:\mathbb{R} \rightarrow \mathbb{R}$.  What are the differences between the following statements?   $\forall v \in \{1, \ldots, n\} ~f(x_v) = 0 \vee g(x_v) = 0$ $f(x_v) = 0 \vee g(x_v) = 0 ~\forall v \in \{1, \ldots, n\} ~$ Calculating $\lim_{x\to+\infty}(\sqrt{x^2-3x}-x)$ Let $f(x) = \sqrt{x^2-3x}$ and $g(x) = x$. Calculate the following limits, showing all working.  I've done the first two -   $$\lim_{x\to0}f(x)\\ =\lim_{x\to0}\sqrt{x^2-3x}=0$$  $$\lim_{x\to-\infty}\frac{f(x)}{g(x)}\\ =\lim_{x\to-\infty}\frac{\sqrt{x^2-3x}}{x}=\sqrt{1-\frac{3}{x}}=1$$  How do I calculate this one?  $$\lim_{x\to+\infty}(f(x)-g(x))$$ A commercial airport being any airport that has regular scheduled passenger flights.  The mathematics of  got me thinking: is the network of scheduled flights a connected graph?  That is, is there a pair (or triplet or even larger set) of airports such that they only have scheduled flights with each other?  Or can you get from any airport to any other?  Ignore vagaries like cargo and general aviation. I'm looking for two airports that I can shuttle between, but would have to drive (or sail) to get to one or the other of them. According to this question:  entire ruSO site shouldn't become hot. But I just saw the following while searching MSE:        Direct link to the question on ruSO:   Perhaps the HNQ filter works on question title (in the current case there are no non-Latin symbols) instead of site origin. Hence, according to the post mentioned before this behaviour should be interpreted as a bug.   However, I suggest to fix such "bug" by taking another feature request in mind: Does Perl have PHP-like dynamic variables? My sketch exports seem to be pixelated even when am exporting it to 1x Adding multiple jars to classpath on commandline What contributes to expanded company details being displayed in Google search results? For some results returned in Google Search, on the right side it displays the company details, logo, contact numbers, etc...   For example, see the following screenshot:    I'd like to know what contributes to this so that I can try to achieve it for my site too. In general, in most places, it is said that using TeX defaults is the best. However, TeX does provide things like \, and \quad etc. When one should use them? Both in general and in math mode in particular. Whats the difference between Unix, Linux and Ubuntu? What is Unix, Linux, Ubuntu?  Are they the same thing or different versions or completely different stuff?  This has always made me confused, any explanation would be great. I'm using R(3.1.1), and ARIMA models for forecasting. I would like to know what should be the &quot;frequency&quot; parameter, which is assigned in the ts() function, if im using time series data which is:  separated by minutes and is spread over 180 days (1440 minutes/day) separated by seconds and is spread over 180 days (86,400 seconds/day).  If I recall right the definition, a &quot;frequency&quot; in ts in R, is the number of observations per &quot;season&quot;. Question part 1: What is the &quot;season&quot; in my case? If the season is &quot;day&quot;, then is the &quot;frequency&quot; for minutes = 1440 and 86,400 for seconds? Question part 2: Could the &quot;frequency&quot;  also depend on what I am trying to achieve/forecast? for example, in my case, I'd like to have a very short-term forecast. One-step ahead of 10minutes each time. Would it then be possible to consider the season as an hour instead of a day? In that case frequency= 60 for minutes, frequency = 3600 for seconds? I've tried for example to use frequency = 60 for the minute data and got better results compared to frequency = 1440 (used fourier see link below by Hyndman)  (The comparison was made by using MAPE for the measure of forecast accuracy) In case the results are complete arbitrary, and the frequency cannot be changed. What would be actually the interpretation of using freq = 60 on my data? I also think it's worth mentioning that my data contains seasonality at every hour and every two hours (by observing the raw data and the Autocorrelation function) Beamer -- not indenting itemize in a single environment The output in the MWE posted at the end of this post is shown below. Notice how the default indentation from itemize gives an asymmetric slide w.r.t the spacing to the left and right of the itemize environment. How can I push the bullet points to the left so that the spaces to the left and right are the same? Such a solution would ideally be:   implementable on a one-off basis, so that it is applied when necessary (since some itemize environments should be given the default indentation) independent of the margin size, so that the solution doesn't need to be changed when the margin size is changed     \documentclass{beamer}   \begin{document}  \begin{frame}{A title} \begin{itemize} \item Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod \item tempor incididunt ut labore et dolore magna aliqua. \item Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi \item ut aliquip ex ea commodo consequat. \begin{itemize} \item Duis aute irure dolor in reprehenderit in voluptate velit esse \item cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat \end{itemize} \end{itemize}    \end{frame} \end{document} How to fix task manager memory column if it shows lies Non in front of hyphenated adjective If one wishes to add "non" in front of a hyphenated adjective, should one add a hyphen after "non?"