I am a British citizen residing in South Africa. In June I will be visiting family in the UK accompanied by my South African wife who holds a valid C Business visa (expiring in 2018). Under the new regulations, can my wife use her existing visa to enter the UK or must she apply for a new visitor visa?
I already have a 6 month valid UK business visa received prior to April 24 2015. I was supposed to travel to the UK in April, but my trip was cancelled on medical grounds.  I am now planning to visit the UK in July for tourism. Would it be fine for me to do so? Will I be allowed to enter the UK? Should I carry the original invite letter and medical certificate to prove why I didn't go the first time?
Okay the scenario I'm thinking of is as follows:   I control a ,  and 3 untapped lands (2 swamps, 1 Island to be perdantic). In my opponents turn he casts a burn spell to kill my duskmantle.   I activate his first ability in response.   The way I am hoping the following interactions will go is:   Duskmantles ability will hit the stack at the top and resolve The burn spell resolves dealing its damage to Duskmantle The burn spell card hits the graveyard and triggers the infinite loop for duskmantle and mindcrank killing my opponent Duskmantle perishes   Is this the way that the stack would pan out? Do I win in this situation regardless of the stack being correct or not above? (I am not fully familiar with how the stack really works in magic) You can see the cards from my deck . How does electricity propagate in a conductor? Securing SSH server against bruteforcing I have a little SVN server, old dell optiplex running debian. I don't have that high demands on my server, because its just a little SVN server... but do want it to be secure.  I just renewed my server to a newer and better optiplex, and started looking a bit into the old server. I took it down after experiencing problems. When I check the logs, its full of brute-force attempts and somehow someone has succeeded to enter my machine. This person created some extra volume called "knarkgosse" with two dirs "root" and "swap1" or something.  Don't really know why and what they do, but sure do want to prevent this from happening again. I find this a bit strange though because I change my password ever few months or so, and the passwords are always random letters and numbers put together... not easy to brute-force.  I know I can prevent root from logging in, and use sudoers... and change the SSH port, but what more can I do?  So I have a few questions:   How can I prevent logging in for 5 minutes after X amount of incorrect tries. Or slow tries down after each incorrect try? Is there some kind of central blacklist which a server can connect to? A blacklist that keeps track of IP addresses that are "unsafe" and should never be granted access? What more can I do to apply safety to my server?   Like I said earlier, I am running Debian 5 with Apache (www-data user problem?), svn, mysql, php, phpmyadmin, hudson. It is on a home network with port forwarding on 80, 443, 8080, 8180, 23 and 22. This is my first time posting on Math exchange. I have been self-teaching myself Mathematics and recently started learning some Algebra. I was posed the following questions, in which I would like to answer before I proceed, but having some trouble finding proper solutions. So the format will be question, and my answer.      What name do we give an element $a \in \mathbb{Z}_n$ that has a multiplicative inverse?   A modular multiplicative inverse of an integer $a$ is an integer $x$ such that $ax \cong 1 (\mod m)$. This means that the remainder after dividing $ax$ by integer $m$ is equal to $1$.      Give an example, for some $n \in \mathbb{N}$, of an element of $\mathbb{Z}_n$, that does not have a multiplicative inverse?   This question is throwing me off because - does the $n$ we speak of matter for both $n \in \mathbb{N}$ and $\mathbb{Z}_n$ ot solely $n$? My guess here would be $0$ because we cannot have an inverse of $0$.      Prove that multiplicative inverse are unique; an element $a \in \mathbb{Z}_n$ cannot have two multiplicative inverses.    Suppose that an element $a\in\mathbb{Z}_n$ has an inverse $a'$. Next, suppose that $a^*$ is also an inverse of $a$. Then, $a'$ is a solution to $a \cdot_n x=1$, and similarly $a^*$ has a solution to $a \cdot_n x=1$.   Lemma: Suppose $a'$ is multiplicative inverse of $a$ in $\mathbb{Z}_n$, then for any $b \in \mathbb{Z}_n$ the equation $a \cdot_n x=b$ has a unique solution, such that $x = a' \cdot_n b$.   By Lemma, equation $a \cdot_n x = 1$ has a unique solution, namely $x=a'=a^*$. Therefore, an element $a\in \mathbb{Z}_n$ cannot have two multiplicative inverses.    Thank you for the help. I would love any constructive feedback for these. If you can help me elaborate on some ideas, that would be really helpful also.  Thank you very much! How to write this boolean expression using only NOR gates? I'm having some trouble understanding how I can convert a boolean expression to a NOR-gate only expression.   What I'm working with looks like \$T = A B' C + A' B C' + A B\$. How would I go into implementing it with NOR gates? There are many times when I'd like to jot a short note in my passport. For example, the business purpose of an entry into a country -- or for countries with automatic passport control and when I don't get a stamp, I'd like to notate my entry and departure.   Can one write in one's own passport? I wouldn't of course write over any stamps, but I might write near them. Or could I use a back page as entry and departure dates?  Yes, I could use a separate piece of paper or a computer file, but having them all in my passport would be handy -- especially when a border officer asks where I've been and why.   And if the laws vary by country, can you note this in your answer? Would it matter if my notations were in ink or pencil? These aren't doodles but business-like annotations and lists. SCJP6 regex issue As the title says: Is a 1st-level spell cast using a 4th-level slot a 1st-level spell, or a 4th-level spell? Reading the book on which I'm learning English, I've come across a weird (for me) omitting the "to" in sentence: "I'd better go meet with him then."  Say, if it were "I'd better go to meet with him then.", would there be any difference between the two sentences? When I should prefer using one instead the other?  P.S. Sorry for my bad English. If I made a mistake somewhere, please correct me. Solutions to $y^2 = x^3 + k$? The equation $y^2 = x^3 + k$ for $k = (4n-1)^3 - 4m^2$, with $m, n \in \mathbb{N}$ and no prime number that p is congruent to 1 modulo 4 divids m, doesn't have any answer and its proof can be obtained by using quadratic reciprocity law.  Do you know answers of this equation for two or three different values of $k$? In addition, do you know any reference about that? Is it safe to eat potatoes that have sprouted? I'm talking about potatoes that have gone somewhat soft and put out shoots about 10cm long.   Other online discussions suggest it's reasonably safe and the majority of us have been peeling and eating soft sprouty spuds for years. Is this correct? I can't seem to get Python to import a module in a subfolder. I get the error when I try to create an instance of the class from the imported module, but the import itself succeeds. Here is my directory structure:  Server     -server.py     -Models         --user.py   Here's the contents of server.py:  from sys import path from os import getcwd path.append(getcwd() + "\\models") #Yes, i'm on windows print path import user  u=user.User() #error on this line   And user.py:  class User(Entity):     using_options(tablename='users')      username = Field(String(15))     password = Field(String(64))     email    = Field(String(50))     status   = Field(Integer)     created  = Field(DateTime)   The error is: AttributeError: 'module' object has no attribute 'User' We've heard it many times, nothing can escape the gravity of a black hole, even light once it's past the event horizon.  If this is true, how can a black hole emit anything?  are massive black holes that have consumed enormous amounts of matter and energy, and then blasted it back out into the universe.  How is this possible?  Time stands still in a black hole, that in itself should stop anything from moving. Is there any hint of of the first Wizarding War being an international event? What is the difference between "twenty-four-hour shift" and twenty-four hour shift"? Just read somewhere about this puzzling puzzle:  What is the difference between:   I'm doing a twenty four-hour shift tonight. I'm doing a twenty-four hour shift tonight. I'm doing a twenty-four-hour shift tonight.   I know number 1 is 20 x 4 hours. Number 2 and 3 is the same as far as I know. Is this true? show that the solution is a local martingale iff it has zero drift Show that the union $\bigcup A_n$ has empty interior in $X$ How do you deserialize json properties that are reserved words in apex? I need help to calculate the  Fourier transform of this funcion  $$b(x) =\frac{1}{x^2 +a^2}\,,\qquad a &gt; 0$$ Thanks. Proof of $\int_0^\infty \left(\frac{\sin x}{x}\right)^2 \mathrm dx=\frac{\pi}{2}.$ I am looking for a short proof that $$\int_0^\infty \left(\frac{\sin x}{x}\right)^2 \mathrm dx=\frac{\pi}{2}.$$ What do you think?  It is kind of amazing that $$\int_0^\infty \frac{\sin x}{x} \mathrm dx$$ is also $\frac{\pi}{2}.$ Many proofs of this latter one are already in this .