I mean, I do read some articles about how to distinguish between those three, but I found that when I wrote stories or blog entries, the rules that I've read is impractical to remember. I found myself going over all the articles over again to decide which one to use, almost for every single sentence.  Can you give a very simple principal rule of thumb, which may cover a large portion of their usage rules? I understand that there's no single "one rule over them all", but at least "one rule over most of them", which I can remember while I write sentences, is already fine by me. :)
I am really confused.  Which preposition is correct?     She is in/at the park.   They are in/at the park.   I am in/at the park.   Should I use in or at in these sentences?
Default behavior of "git push" without a branch specified When a 0-1-matrix with exactly two 1’s on each column and on each row is non-degenerated? [1] Let $A$ be an $n\times n$ matrix with entries in the set $\{0,1\}$ which has exactly two ones in each column and two ones in each row.  Give necessary and sufficient conditions for the rank of $A$ to be $n$. "Track changes" in LaTeX I am writing a scientific paper with my collaborator. We have submitted a version to a journal and now we got a review from them, so we need to fix a few things. In Microsoft Word there is the option to "track changes", which displays the deleted text as crossed out and the new text bolded (if I remember the details correctly). Is there a way to achieve a similar result in LaTeX?  I was thinking to create a new file for the revised version and then write a script which would basically compare the two files and make the differences either bold or crossed out before sending it to latex. Is there a tool that already does it? I am going to start a phd at the US with an F1 visa. University told me that I could enter the US only 30 days before the date on I-20. Since English is not my first language (and this would be a big change in my life) I would like to go there by June.  The thing is that I have an European passport with a valid ESTA. My plan would be to arrive with this passport, stay 4-6 weeks , go to Canada for a short vacation (maybe flight maybe by land) and come back to the USA with F1 visa.  I have two questions about this:  1) is this possible?   2) If yes, how could I justify knowing I will lose my come-back flight during my first entry? (I would purchase round trip because one-way are too expensive, probably with less than 90 days difference) Network reputation graph becomes nervous when clicking quickly, backs away slowly How to remove white space before reference? Patching commands to remove surrounding whitespace I'm using the todonotes package to add little margin notes to my text, however writing  Hello\todo{test} World!   removes the interword space as is already pointed out in . So I tried  \pretocmd{\todo}{\@bsphack}{}{} \apptocmd{\todo}{\@esphack}{}{}   and this adds the interword space but simply outputs all parameters instead of passing them to \todo.  Full MWE:  \documentclass{article}  \usepackage{etoolbox} \usepackage{todonotes}  \makeatletter \pretocmd{\todo}{\@bsphack}{}{} \apptocmd{\todo}{\@esphack}{}{} \makeatother  \begin{document} Hello\todo{test} World! \end{document} Why do my LED lights stay on, even when the switch is off? I have two LED lamps in my corridor, and when I switch them off, they keep emitting light (not very strong, but it's annoying at night).  What can it be? How can I fix it? How to write uncertainties with the \pm symbol "10 ± 1 K" by using siunitx? Using the siunitx package, if I specify an error with the \pm symbol then it automatically converts it to a form using parenthesis. I would like it to not do this and keep the \pm symbol, but still space the elements of the quantity and symbol in a good way.  e.g. \SI{10 \pm 2}{\kelvin} would produce 10(1) K  I would like it to produce: 10\pm1 K or something similar with spacing taken care of. Possible to bake texture to new UV map? How do I convince someone that $1+1=2$ may not necessarily be true? Me and my friend were arguing over this &quot;fact&quot; that we all know and hold dear. However, I do know that $1+1=2$ is an axiom. That is why I beg to differ. Neither of us have the required mathematical knowledge to convince each other. And that is why, we decided to turn to Math Stackexchange for help. What would be stack's opinion? Standard packages for compact SMT crystals There is an old and bog standard form factor for SMT crystals - HC49/US. The problem is that HC49/US takes a lot of real estate on the board.  It's 12mm long.  Another problem with crystals and oscillators in general is that they often become long lead time items.  [This is my experience.]  There are lots of small form factor crystals from various manufacturers.  But, at a glance, it seems that there is no standardization of form factor.  It’s nice when packages are standardized.  It alleviates the long lead time problem.  Crystals from manufacturer B may be used, if crystals from manufacturer A are out of stock.  Are there standard form factors for compact SMT crystals?  Update  Armed with the insights from Gribo and Gustavo, I did a more focused survey.  Found that 12MHz in 3.2x2.5mm package are produced by: Abracon, Citizen, Epson, Fox, ECS, TCS, NDK.  To be included in this list, the part had to be in stock at DigiKey.  It turns out that 3.2x2.5mm package is common across many manufacturers. I can't run this latex script I currently have a masters degree in an engineering field and I don't currently have any PhD degrees (I may study for a doctorate degree in future). It happens that when I go to conferences or scientific occasions, even in the emails I receive from people; they use a doctor prefix for my name; but I do not have a PhD degree.  What is a good etiquette to deal with such thing? Should I directly tell them that I do not have a doctorate degree? Or should I neglect such a mistake by them and don't do anything?  I think it is unethical not to correct such thing, because the person may still think that I have a PhD degree; and such wrong usage of title should be corrected some way. Once a person used doctor title for my name in an email and I just added a line in my reply to his email, stating that I have a masters degree. I accepted an answer to this question:    but the bounty was awarded by Community&thinsp;♦ to another answer. Why did this happen? Integrating radial free fall in Newtonian gravity Interpreting plot.lm() How do you change from icon to list view in 20.4 The reason that I ask is because this is happening to LiDAR, and I am inclined to use lidar because it is easier to read. What is the difference between a neural network and a deep neural network, and why do the deep ones work better? I haven't seen the question stated precisely in these terms, and this is why I make a new question.  What I am interested in knowing is not the definition of a neural network, but understanding the actual difference with a deep neural network.  For more context: I know what a neural network is and how backpropagation works. I know that a DNN must have multiple hidden layers. However, 10 years ago in class I learned that having several layers or one layer (not counting the input and output layers) was equivalent in terms of the functions a neural network is able to represent (see Cybenko's ), and that having more layers made it more complex to analyse without gain in performance. Obviously, that is not the case anymore.  I suppose, maybe wrongly, that the differences are in terms of training algorithm and properties rather than structure, and therefore I would really appreciate if the answer could underline the reasons that made the move to DNN possible (e.g. mathematical proof or randomly playing with networks?) and desirable (e.g. speed of convergence?)