Given that , I wonder what happens if a French citizen goes to 's strip of casinos and hotels between the Cambodian and Thai passport control counters, assuming that they do not have any special visas to enter Cambodia or Thailand. Are they stuck in the strip of casinos and hotels?  To save some time for people going through answers in the dupe question, assuming one enters from Thailand: one can enter back Thailand and the Thai departure stamp gets :  No idea whether this still applies during the COVID-19 travel restrictions.
Last month, I was travelling on a backpacking trip across Russia and the Baltic states (Schengen zone). I'm an Indian by nationality. So I had to get the respective single entry visa for Russia and Schengen Europe.  At the border crossing into Estonia by road (at Ivangorod-Narva), I exited the Russian border with an exit stamp (so now I can't go back to Russia since I had a single entry visa). When I was at the immigration checkpoint of Estonia, I was heavily questioned on the intent of my travel to Europe while entering Estonia by road.   Though I finally got into Europe, It got me wondering - what happens if a foreign national is denied entry into a country not at the airport but by land between 2 countries he cannot go into ?  Generally, if you are denied entry at the airport the airline has the obligation to fly you back to your country. But what happens when you are stuck between two countries and you cant get into either ? What happens to you then ?
I wanted to align a set of equations to left. I found on the Internet that you can do it easily with align* environment.   I found it here:   So I did it:  \begin{align*}  f(b)-f(a)=&amp;f((b_1,b_2,\dots,b_k))-f((a_1,a_2,\dots,a_k))=\ &amp;=\sum_{i=1}^{k}[f((a_1,\dots,a_{i-1},b_i,\dots, b_k))-f((a_1,\dots,a_i,b_{i+1},\dots, b_k))  \end{align*}   Unfortunately, I got bunch of red errors saying that there are missing $s. Why? Doesn't that align* environment provide a math environment already? Reduce Spacing In $$ In math, one often needs to put a letter inside the symbols &lt;&gt;, e.g. to denote a cyclic group &lt;x&gt; generated by some element x. However, plain text displays the symbols &lt; and &gt; as an upside down exclamation point and an upside down question mark, respectively, while math type displays a large space like so:  &lt; x &gt;    Is there some way to reduce this spacing? In  Deathly Hallows, when Harry, Ron, and Hermione are at No. 12, Grimmauld Place, Harry summons Kreacher from the kitchens at Hogwarts where the elf has been working on Harry’s orders given a year previously.  When the trio’s heist in the Ministry of Magic ends with Hermione inadvertently bringing Yaxley inside the perimeter of the Fidelius charm that protects Grimmauld Place, the trio leg it and dare not return there for fear that it’s now crawling with Death Eaters.  Before they leave for the Ministry in the morning, Kreacher is talking about making a stew or pot roast or something for dinner. After the trio go on the run and camp out in the tent, Harry thinks of poor Kreacher preparing a dinner they’ll never return to eat, but they dare not summon him lest a Death Eater tag along (like how Dobby ‘tagged along’ with Kreacher when Harry called him to have him follow Draco in Half-Blood Prince).  The next time we see Kreacher is during the Battle of Hogwarts where he leads the house-elves from the kitchen with battle-cries of “For Master! For Harry Potter!” (or something like that), so he’s clearly lost none of his new-found loyalty to Harry.  Harry is still Kreacher’s master throughout the book, and since he does not communicate at all with Kreacher after their escape from the doorstep, he cannot have ordered Kreacher to return to Hogwarts to work there again.  We know that house-elves can go against their masters’ wishes, but this usually entails them punishing themselves rather brutally, and Kreacher does not seem to have been constantly injuring himself for the better part of a year at Hogwarts.  So when and how does Kreacher leave his master’s house without orders and return to Hogwarts? I want to uninstall VMware Player on my Ubuntu 12.04 LTS system. How should I uninstall it? My online friend is asking for money in order to visit my home country. Is this a legit request or a scam? I struggled with this over the weekend, and need to remap my mouse buttons. How do I implement basic "Long Polling"? Why exactly do sometimes universal covers, and sometimes central extensions feature in the application of a symmetry group to quantum physics? There seem to be two different things one must consider when representing a symmetry group in quantum mechanics:   The universal cover: For instance, when representing the rotation group $\mathrm{SO}(3)$, it turns out that one must allow also $\mathrm{SU}(2)$ representations, since the negative sign a "$2\pi$ rotation" induces in $\mathrm{SU}(2)$ is an overall phase that doesn't change the physics. Equivalently, all representations of the Lie algebra are what we seek. ($\mathfrak{so}(3) = \mathfrak{su}(2)$, but although every representation of the algebra is one of the universal cover, not every representation of the algebra is one of $\mathrm{SO}(3)$.) Central extensions: In conformal field theory, one has classically the  of infinitesimal conformal transformations. From the universal cover treatment one is used to in most other cases, one would expect nothing changes in the quantum case, since we are already seeking only representation of an algebra. Nevertheless, in the quantization process, a  appears, which is often interpreted to arise as an "ordering constant" for the now no longer commuting fields, and we have to consider the  instead.   The question is: What is going on here? Is there a way to explain both the appearence of universal covers and central extensions in a unified way? There are many times when I curse the autocorrection mechanism for changing what I typed, but overall, much of the corrections are welcome so I don't really want to disable it. I do want to have it do it's work but alert me when it makes each change so I don't have to proofread everything or focus with perfect attention to the screen to see the momentary red and/or blue underlining that alerts me to the machine override.  I would love a way to turn on an audible beep (customizable of course) so that I also get a warning each time my typing gets corrected (and only when autocorrection occurs). No Sound (Dummy Output) error Ubuntu 19.10 2018 monthly product team updates Mid-2017  started publishing monthly updates. This post will continue that effort into 2018. (.)  Updates are posted at the beginning of the month. They cover what was done last month, what is still in progress and new work that will be started in the current month.  Updates:      (CoC, nav, OpenID, responsive design, bugs, campaigns)  (CoC, comment flags, nav, OpenID)  (question wizard, nav, user survey, OpenID)  (tag watching, GDPR)  (responsive design, tags, teams)  (responsive design, OpenID, teams, sponsorship)  (responsive design, facebook auth, question lists, teams)  (newsletter, sign up, Documentation reputation, channels)  (top bar issues, hats, question template) What is the best way to solve equations like the following:  $9x \equiv 33 \pmod{43}$  The only way I know would be to try all multiples of $43$ and $9$ and compare until I get $33$ for the remainder.  Is there a more efficient way ?   Help would be greatly appreciated! How to analyze trend in non-periodic time series Suppose I have following non-periodic time series. Obviously the trend is decreasing and I would like to prove it by some test (with p-value). I am unable to use classic linear regression due to strong temporal (serial) auto-correlation among values.  library(forecast) my.ts &lt;- ts(c(10,11,11.5,10,10.1,9,11,10,8,9,9,                6,5,5,4,3,3,2,1,2,4,4,2,1,1,0.5,1),             start = 1, end = 27,frequency = 1) plot(my.ts, col = "black", type = "p",      pch = 20, cex = 1.2, ylim = c(0,13)) # line of moving averages  lines(ma(my.ts,3),col="red", lty = 2, lwd = 2)     What are my options? Two different solutions to integral Given the very simple integral  \begin{equation} \int -\frac{1}{2x} dx \end{equation}  The obvious solution is  \begin{equation} \int -\frac{1}{2x} dx = -\frac{1}{2} \int \frac{1}{x} dx = -\frac{1}{2} \ln{|x|} + C \end{equation}  However, by the following integration rule \begin{equation} \int \frac{1}{ax + b} dx = \frac{1}{a} \ln{|ax + b|} + C \end{equation}  the following solution is obtained \begin{equation} \int -\frac{1}{2x} dx = -\frac{1}{2}\ln{|-2x|} + C \end{equation}  Why are these solutions different? Which is correct?   The second solution can be simplified \begin{equation} -\frac{1}{2}\ln{|-2x|} + C = -\frac{1}{2}\ln{|-2|} -\frac{1}{2}\ln{|x|} + C= -\ln{\frac{1}{\sqrt{2}}} - \frac{1}{2}\ln{|x|} + C \end{equation} but they still differ. Why did the command ":(){ :|: & };:" make my system lag so badly I had to reboot? Do not run this command to 'test' it unless you are prepared for a crash and/or force-rebooting your system.  I was in my Virtualbox running 12.04 trying to compile an app, and while waiting I happened to chance upon a forum where a comment said:   Try :(){ :|: &amp; };:  Fun, too, and doesn't need root.  Without thinking, I ran it in my gnome-terminal. It made my 12.04(in Virtualbox) lag so badly, I had to shut it down. My question is what does this command do?   :(){ :|: &amp; };: Validity of conditional statement when the premise is false. Use template_include with custom post types I want to check for an appropriate template in the theme folder before falling back to the file in my plugin directory. Here’s my code:  add_filter('template_include', 'sermon_template_include'); function sermon_template_include($template) {     if(get_query_var('post_type') == 'wpfc_sermon') {         if ( is_archive() || is_search() ) :            if(file_exists(TEMPLATEDIR . '/archive-wpfc_sermon.php'))               return TEMPLATEDIR . '/archive-wpfc_sermon.php';            return dirname(__FILE__) . '/views/archive-wpfc_sermon.php';         else :            if(file_exists(TEMPLATEDIR . '/single-wpfc_sermon.php'))               return TEMPLATEDIR . '/single-wpfc_sermon.php';            return dirname(__FILE__) . '/views/single-wpfc_sermon.php';         endif;     }     return $template; }   Problem is, it doesn’t work! :-) It always picks the file in my plugin folder. Any idea what to do? I’ve tried alot of variations but I can’t seem to get anything to work! Thanks in advance! Jack  EDIT  I'm expecting the archive-wpfc_sermon.php to be returned from the theme folder if it exists. However, the file from my plugin always gets returned. Thanks for your help! This is from my Sermon Manager plugin available in the repository. There is no such thing as magnetism? Here's an interesting "proof" that there is no such thing as magnetism. I know the answer but I love this so much I had to ask it here. It's a great way to confuse people!  As we all know, $$\nabla \cdot\vec{B} =0$$ Using the divergence theorem, we find $$ \iint_S \vec{B} \cdot \hat{n} \, dS = \iiint_V \nabla \cdot \vec{B} \, dV = 0$$ Since $\vec{B}$ has zero divergence, there exist a vector function $\vec{A}$ such that $$\vec{B} = \nabla \times \vec{A}$$ Combining the last two equations, we get $$\iint_S \hat{n} \cdot \nabla \times \vec{A} \, dS = 0$$ Applying Stokes' theorem, we find $$\oint_C \vec{A} \cdot \hat{t} \, ds = \iint_S \hat{n} \cdot \nabla \times \vec{A} \, dS = 0$$ Therefore, $\vec{A}$ is path independent and we can write $\vec{A} = \nabla \psi$ for some scalar function $\psi$. Since the curl of the gradient of a function is zero, we arrive at: $$\vec{B} = \nabla \times \nabla \psi = 0,$$ which means that all magnetic fields are zero, but that can't be!  Can you see where we went wrong? How to concatenate a std::string and an int I thought this would be really simple, but it's presenting some difficulties. If I have std::string name = &quot;John&quot;; int age = 21;  How do I combine them to get a single string &quot;John21&quot;? Is the following layout possible with the subfigure package?