Removing element in ArrayList using INDEX causing java.util.ConcurrentModificationException
Iterating through a Collection, avoiding ConcurrentModificationException when removing objects in a loop
Is there a difference between "think of something" and "think about something"? I've also met "have heard of/about something". How do I capture the milky way? Can the milky way actually be photographed ? I know the image is manipulated, and is probably a composite, but how do you capture such contrast in the milky way? Is an equitorially mounted scope required? Any advice or pointers are welcome, thanks.  I'm heading out towards much less light polluted areas middle of next week and I want to try some nighttime sky captures with my 7D.  Additional info: I just found  on wikipedia that says: 54s, tripod mounted 5D, 16mm lens, f/2.8, ISO800. What else do I need to be aware of? My 7D is only an APS-C and the widest lens I have is 19mm. I'm thinking that might not be wide enough to capture an interesting shot? How to add “jQuery” onclick functionality for a column each row in jQgrid to display different popups for different rows Equivalent statement of AC or not? Here's a corollary of AC stating that: if there exists an onto mapping $f:A\to B$, then there exists a 1-1 mapping $g:B\to A$. What I'm confused about is that whether or not  AC can be derived from this proposition, in return? I have tried but haven't found a proof. Any help would be appreciated. Intersection of all $p$-Sylow subgroups is normal Why does the CRT formula yield a solution of a congruence system? What is the name of an 80s TV movie where a man acquires endurance powers and quick self-healing ability after a crash with a vehicle containing radioactive material? Is there an optimal loss function for dealing with imbalanced classes? I'm aware that there are many ways of dealing with datasets where there is a strong class imbalance in the target variable: downsampling the more prevalent and less important class, over-weighting the valuable minority class, etc. Are there any loss functions that are ideally suited for these types of problems? I've heard of AUC, but AUC sounds like a means of evaluating a model once its training is complete (correct me if I'm wrong). Log loss and squared loss penalize a model's over confidence, but overconfidence and class imbalance seem unrelated. Is that true? I'm running 12.04 - I installed kubuntu to try it out and realized that with all the bloatware applications that I didn't want it anymore - I was able to uninstall the kubuntu-desktop but there are still packages left over... How can I make sure I get rid of EVERYTHING Kubuntu installed - even the kde leftovers?  Here's some of what's left when I ran sudo apt-get autoremove kde then "tab" it displayed this:     kdeaccessibility              kdepim-runtime kdeadmin   kde-runtime kde-baseapps                  kde-runtime-data   kde-baseapps-bin              kdesdk-dolphin-plugins kde-baseapps-data   kde-style-oxygen kde-config-cron               kdesudo kde-config-gtk    kdeutils kde-config-touchpad           kde-wallpapers   kdegames-card-data            kde-wallpapers-default   kdegames-card-data-extra      kde-window-manager kde-icons-mono   kde-window-manager-common kdelibs5-data                 kde-workspace   kdelibs5-plugins              kde-workspace-bin kdelibs-bin   kde-workspace-data kdemultimedia-kio-plugins   kde-workspace-data-extras kdenetwork   kde-workspace-kgreet-plugins kdenetwork-filesharing   kde-zeroconf kdepasswd                     kdf kdepim-kresources   kdm kdepimlibs-kio-plugins        kdoctools   Those are all installed by kubuntu... correct?  I just want to go back to my Ubuntu 12.04LTS with Gnome2-classic and without all the kubuntu extras.  I started it off by just removing unnecessary apps that came with kubuntu-full - then realized I didnt want the whole thing at all and uninstalled kubuntu-full but it still says I have these as well:     alex@griever:~$ sudo apt-get --purge remove kubuntu-   kubuntu-debug-installer           kubuntu-netbook-default-settings   kubuntu-default-settings          kubuntu-notification-helper   kubuntu-firefox-installer         kubuntu-web-shortcuts How to show to the user a progression in a script? Using ls to find files that end in a character, ignoring extension I am supposed to use ls to find files that end in a certain letter, but it does not matter if the file has an extension or not.  For example, I want it to do this  &gt; ls test test.txt test.ascii other.txt  &gt; ls [something] test test.txt test.ascii  So that I can find files that end with a 't', but it doesn't include the file where the extension ends in t  Edit: I am supposed to assume that the only period characters in the filename will be for the extension and there will be no others Computing the Galois group of $x^4+ax^2+b \in \mathbb{Q}[x] $ I want to compute the Galois group of some polynomials, but I want to see some examples first. For example this proposition could be helpful. I don't know how to prove it &lt;.&lt;  Let's consider a polynomial $f(x)= x^4+ax^2+b \in \mathbb{Z} $. Let $ \pm\alpha , \pm\beta$ denote the roots of $f(x)$. Note that $f$ is irreducible iff $\alpha^2, \alpha\pm\beta \notin \mathbb{Q}$. So let's suppose that $f(x)$ is irreducible. Let's denote $G$ the galois group of $f$ (the Galois group of the splitting field $\mathbb{Q}(\alpha,\beta)/\mathbb{Q}$)  $i)$ $G\cong V$ the Klein 4-group iff $\alpha\beta \in \mathbb{Q}$  $ii)$ $G\cong \mathbb{Z}_4$ iff $\mathbb{Q}(\alpha\beta)=\mathbb{Q}(\alpha^2)$  $iii)$ $G\cong D_8$ the dihedral group of order 8, iff $\alpha\beta \notin \mathbb{Q}(\alpha^2)$  I need help with the proofs of this propositions... Well I'm very lost with the computation of Galois group, some care must be exercised, I don't have it. For example I know that Galois group acts transitively, in the sense that $u\in K/F$ a galois extension, the other roots of the minimal polynomial of $m_u(x)\in F[x]$ are precisely the elements $ \sigma(u)$ , where $\sigma \in Gal(K/F)$. And clearly any automorphism, is determined by only the value of a basis. In this case we are working on $\mathbb{Q}(\alpha,\beta)$, so I have to know the values of both. But I have to respect the algebraic relations involving $\alpha , \beta$ I proved that in $i),ii)$ $\mathbb{Q}(\alpha,\beta) = \mathbb{Q}(\alpha) $ So I have to know the values on $\alpha$.   My first question is: If in both cases $i),ii)$, I have an extension of degree 4 (so $|G|=4$) I have to map $\alpha$ to determine the automorphism, but I have also to map $\alpha$ to all of it's four roots. Why the galois group in this case are different?  My second question is about $iii)$ I have no idea How to attack it. Vertical component of moving weight at a 45 degree angle Here's an easier one. I use the leg press machine at the gym so I don't have to worrying about hurting myself while lifting heavier weight.  The weight glides on a track that looks to be 45 degrees.  What's the equation to figure out how much weight I would be able to squat normally.  IE the vertical component of moving 400lbs at a 45 degree angle. Given two ciphertexts $c_1 = enc(p_1)$ and $c_2= enc(p_2)$ using any additive homomorphic encryption scheme (or specifically Paillier).   Can we find out whether the underlying plaintexts $p_1,p_2$ are equal without decrypting $c_1,c_2$ i.e. homomorphically? How to run shell script via terminal How to reinstall Ubuntu in dual boot with Windows 10? I have Ubuntu 15.10 and Windows 10 dual-booted, but I want to reinstall Ubuntu in the same partition without making any changes or causing problems in the dual boot option and without removing Windows.  Is it possible? Any guide on how to do it? Use the beamer TOC style elsewhere The new GNU Octave 4.0.1 was released March 23, 2016.  I would like to find some standard way to install it in El Capitan (mine OS X 10.11.3) because it has significantly better support in some functions than Matlab, discussed in the thread .  I do brew search octave and get  homebrew/science/octave    Caskroom/cask/octave       Caskroom/cask/xoctave       where one of the first two should be a correct one. The project's homepage  for OS X is down  about installing Octave on OS X systems.  There is also ruby's way of installing Octave described in the thread  but for Yosemite.  I would like to find some standard way of getting Octave for OS X.   I do successfully brew update and brew upgrade before the commands. My Homebrew is 0.9.5 (git revision 80d1; last commit 2016-03-24).  . I run brew info octave but I get  Error: No available formula with the name "octave"     How can you install Octave in some standard way for El Capitan? If I change the password for the root user is that going to automatically change the password for the user account?   I found this link for root:    How do I change the user account password? What is different about the Mac ISO image? At that location there is an ISO image which is described as "This image is adjusted to work properly on Mac systems."  What specific problems on the Mac does this image address that the standard images don't? I ask because I need to know which ISO to recommend to Apple Mac users.