I have citizenship for Australia, UK &amp; Ireland, and possess a passport for each and am planning a trip for this year. Please can you help me understand the best way to travel on these if I'm travelling from Sydney to London to Dublin, then Amsterdam, London, Sydney. It's a little complicated and I'm tempted to simply travel on my AU passport only as that's where I live and my other two passports are currently blank.   Any advice would be appreciated! Thanks.
I am a citizen of two different countries, and have two passports.  How should I use my passports when traveling?
What is an example of perfect collinearity in terms of the design matrix $X$?  I would like an example where $\hat \beta =  (X'X)^{-1}X'Y$ can't be estimated because $(X'X)$ is not invertible. Dictionary application needs to download dictionary "Apple Dictionary" before use If $i=\sqrt{-1}$, is $\large\sqrt{i}$ imaginary?     Is it used or considered often in mathematics? How is it notated? What conservation law corresponds to Lorentz boosts? Noether's Theorem is used to relate the invariance of the action under certain continuous transformations to conserved currents. A common example is that translations in spacetime correspond to the conservation of four-momentum.  In the case of angular momentum, the tensor (in special relativity) has 3 independent components for the classical angular momentum, but 3 more independent components that, as far as I know, represent Lorentz boosts. So, what conservation law corresponds to invariance under Lorentz boosts? Please revisit the CAPTCHA & China issue Back in 2012 when China first blocked all Google services, thereby preventing non-VPN users from proving their non-roboticness, someone quickly opened this thread on Meta:    The consensus at the time was "we can't think of a better way of doing things".  Well, 3 years have passed and China is showing no signs of unbanning Google. Meanwhile, CAPTCHA technology has evolved. Can the SE admins please revisit this situation? People in China without a VPN are completely unable to prove they are not bots. I couldn't even search for the phrase "pgp" on Security.SE without hitting the human verification barrier. Blocking questions is one thing, but searches also? I think that's too strict.  (yes, I wrote this with my VPN) Rejecting a PhD offer after having accepted it. Advice? I have accepted a PhD offer from a very good university to do a project very close to my interests. I have told the project supervisor I accept it. In the meanwhile I have managed to secure a PhD offer from another 2 universities much better in world rankings and with better research groups and better faculty. Additionally these 2 universities do research exactly on what I want to devote my PhD research.  My only commitment to the first university is a mail confirming I accept. Nothing else. I understand declining the offer after already having accepted it is quite dishonest but it is a huge decision that will affect my future in a very significant level.   I would like your opinion and I would also like to ask for possible consequences of such an action. As far a postdocs concerned, in the first university there is no chance I ever get a postdoc since they do not actually do research on my area (except for the prospective supervisor and even he not as much).  UPDATE I have decided to do as I was afraid to. I have decided to choose a different university than the first one that I have already accepted the offer. My offer acceptance included:    An online "I accept" statement. An e-mail I sent stating "I accept the scholarship and this University is my first option"   I do not have any legal commitments since I have not signed anything. The supervisor of the first university though is really nice to me and continuously was sending me mails. How do I very nicely tell her I will not be joining in the end? Additionally the place I will go in the end will be for research in Mathematics and not Physics. Can I use this as a part of a sensical excuse?  WHAT I HAVE CHOSEN AND WHAT THE CONSEQUENCES WERE  I think that I should let people, especially other beginning grad students know what happened with my case. I have chosen to nicely tell the first university I got accepted that I will not be attending and will not be pursuing a PhD there since I decided I have different research interests (which is true). I had applied there in the first place since I was not sure what I wanted to do and because it was a nice program. Despite that, I got an offer from a World top university to work on 100% my research interests. I explained this to them, the first uni, and they happily let me go and wished me good luck, especially the supervisor who faught a lot secure me funding. I was lucky. Is there a term for when just by saying that something is broken and showing it to someone fixes the issue? This seems to be a common enough occurrence that it would merit its own phrase. I imagine it might be some sort of subset of Murphy's Law. But it's specific enough that Murphy's Law doesn't quite address it.  Do you know when you are banging your head against a wall for hours trying to fix something? And then when you finally give up and try to get someone else to come fix it (or even just look at it to see that it's broken), it's working perfectly as if nothing had ever happened? And at this point, you're just trying to convince the other person that it was broken in the first place.  It'd at least take some of the frustration out of the experience if you could both just laugh about &lt;insert the phrase for it here&gt;. But as it is now, I basically have to go through the whole paragraph above to say it, and at that point the joke is kind of lost. How do I clear all user defined symbols? What should be taken into consideration when mixing fluxx sets?   I played a game of Stoner and Zombie fluxx mixed the other day, and I found it super fun. It add variance to the theming, and especially with the Stoner fluxx (if you're playing with the, ahem, special rules) and stretches it out.   What are the potential pitfalls of mixing sets, and what else should be taken into consideration? To make Latin-letter variables bold I can use e.g. \mathbf{a}, but while putting Greek letters or symbols such as \nabla inside \mathbf doesn't cause any errors or warnings, it also doesn't do anything else.  What is the best way to make bold math symbols, in particular Greek letters and \nabla? In my cover letter I want to write that I am a graduate student in statistics. But I am not sure about the "in". So what is correct?     I am a graduate student in statistics.      I am a graduate student of statistics. Factors for max CP at a particular trainer level? Construct ideals in $\mathbb Z[x]$ with a given least number of generators MySQL convert date string to Unix timestamp I am trying to modify output in my twig file. In D7, I was able modify data in my array with this  check_markup($tweet-&gt;text, 'full_html');   and I see that this function still exists in D8. However, I'm not sure how I would use this in a filter in twig. This is what I have so far:  {% for tweet in params.tweets %} &lt;div class="tweet-wrapper"&gt; &lt;div class="tweet-profile-image"&gt;     &lt;img src='{{ tweet.user.profile_image_url }}'/&gt; &lt;/div&gt; &lt;div class='tweet-text'&gt;     &lt;!--check_markup($tweet-&gt;text, 'full_html');--&gt;     {{ tweet.text }} &lt;/div&gt;   &lt;/div&gt; {% endfor %}   I actually tried to do this before I sent it to the template as well, but it didn't change anything:   foreach($tweets as $tweet) {   $tweet-&gt;text = check_markup($tweet-&gt;text, 'full_html');   $cleanTweets[] = $tweet; } dpm($tweets); $params = array('tweets' =&gt; $cleanTweets); $tweet_template = array('#theme' =&gt; 'twitter_pull_tweet_listing', '#params' =&gt; $params); return $tweet_template;   What I'm trying to do here is make drupal create links for web links in the twitter tweet text. This worked fine for me in D7. Saving Mathematica kernel state? Looking for a book with parallel universes like pages, possibly with "maze" in title, and a black Jewish female character Looking for a book. A series,  actually.  The main characters were a Jewish man and a black woman who was his wife. There was a running gag when she would tell people her last name and they thought it was unusual that a black woman would have a Jewish name.    They went on adventures in parallel dimensions. I believe that each book had a word repeated in the title, maybe "mirror?" Or "maze?" Or "page..."  it seems they jumped into worlds through a tool like a mirror or a book.   The parallel universes were like pages, and the pages closest to you were most similar but the further you got the further they were from your life.  One page over might be that you had something different for breakfast and so now you have a tummy ache, a few more pages over you might have become a prostitute, too far and it was theorized that humans had evolved differently altogether, I didn't get that far in the series.  For adults, and humorous.  I read them about 15 years ago, so they are not new. I would love to find them again. Examples:        Data can be imported to and exported from the application.    Data can be imported and exported from the application.   Data can be imported to the application and exported from it.                  The manager defined the products that should be added to and removed from the store.   The manager defined the products that should be added and removed from the store.   The manager defined the products that should be added to the store and removed from it.      I assume that the third sentence is correct in my examples. My question is whether the two other sentences are correct. I'm looking for a time and memory efficient solution to calculate a  in C. I need to avoid dividing because I'm on a PIC 16 which has no dedicated division unit.  At the moment, I just store all values in a  and simply store and update the sum each time a new value arrives. This is really efficient, but unfortunately uses most of my available memory... How do you reverse a string in place in C or C++? How do you reverse a string in C or C++ without requiring a separate buffer to hold the reversed string?