Reducing degrees of freedom of a system described by an equation
Procedure for reducing the degrees of freedom of an arbitrary system
Determine the number of ways to colour a 1 by n grid using the colours red and white if an even number of squares are to be coloured red. Earlier today, I was suspended from chat due to an inappropriate message (I totally deserved it, but that's not the point). I looked at my phone, and this is all that it told me:    ...which confused me because chat was still moving as normal. I didn't realize that I had been suspended until I checked on my computer to see what the heck was going on.  To me, "This room is read-only" sounds like some sort of database lockup or something related specifically to the room, not the user. It doesn't give any feedback to indicate that the room will be "read-only" for 30 minutes, and doesn't mention that all other rooms are also "read-only". Even a message saying just "You have been suspended from chat" would be more helpful. I have tried as following:  1. Turn off: export DISPLAY=:0.0 &amp;&amp; xset dpms force off  2. Turn on: export DISPLAY=:0.0 &amp;&amp; xset -dpms   Which works but that is a temporary solution, which does not fix my problem yet. When i reboot system it start again and again the same auto turn off mode.   How can i now remotely using SSH turn it off forever?  IMPORTANT:  - KIOSK (ATM machine will use this option) - 24/7 advertising display/slides will use this   Optional Note: this guide i followed   , but permanent solution did not worked. I have 16GB RAM. Do I need 32GB swap? How to remove headers and footers for pages between chapters? Everywhere I get to read statements like EM radiations and EM fields carry "energy as well as momentum " . I wonder if energy and momentum are inalienable . Is it possible for a field to carry only energy without having any momentum term ? I mean isn't it sufficient to say that fields or EM waves carry energy or Doesn't the ability to transfer energy, of the fields, automatically imply that they can change the momentum of another particle while transferring energy to them? How to remap an existing keybinding in Zathura I have an unlocked North American (Canada) iPhone 5s, where can I buy a data only SIM card in Japan ? I'm not interested in renting nor in a voice plan, I'll be staying for 4 weeks.  I'll be landing in Tokyo, so preferably around there. Can I get them from the airport somewhere ? I'm assuming I won't have problems with the network/frequencies, am I correct ? SSH welcome message on 17.04 shows notice about 12.04 I just did a do-release-upgrade going from Ubuntu 16.04 to 17.04. However, now when I login via SSH I have the following message   Welcome to Ubuntu 17.04 (GNU/Linux 4.10.0-20-generic x86_64)   * Documentation:  https://help.ubuntu.com  * Management:     https://landscape.canonical.com  * Support:        https://ubuntu.com/advantage  Ubuntu 12.04 LTS end-of-life was April 28, 2017 -- Upgrade your Precise systems!  $ sudo do-release-upgrade -m server  0 packages can be updated. 0 updates are security updates.   My question is, how can I remove the   Ubuntu 12.04 LTS end-of-life was April 28, 2017 -- Upgrade your Precise systems!  $ sudo do-release-upgrade -m server   it wasn't there prior the release-upgrade  I checked and I am on Zesty  lsb_release -a No LSB modules are available. Distributor ID: Ubuntu Description:    Ubuntu 17.04 Release:    17.04 Codename:   zesty   My question is not, how can I remove this message, this I found. My question is more, is there a reason why this appears after a release-upgrade? Is this message something generic not taking into consideration the current version of Ubuntu? Or maybe my system is not updated properly? Avro Bengali keyboard switches to Malay (Jawi) after upgrade to Ubuntu 17.04 Some publications capitalize He, Him, etc., when referring to a god.    What is this practice called? 'Proper noun' is rather generic. Difference between "per" and "a" Why might one also use a blank constructor? I was reading some Java recently and came across something (an idiom?) new to me: in the program, classes with multiple constructors would also always include a blank constructor. For example:   public class Genotype {   private boolean bits[];   private int rating;   private int length;   private Random random;    public Genotype() {              //  &lt;= THIS is the bandit, this one right here     random = new Random();   }    /* creates a Random genetoype */   public Genotype(int length, Random r) {     random = r;     this.length = length;     bits = new boolean[length];      for(int i=0;i&lt;length;i++) {         bits[i] =random.nextBoolean();     }   }    /* copy constructor */   public Genotype(Genotype g,Random r) {     random = r;     bits = new boolean[g.length];     rating = g.rating;     length = g.length;      for(int i=0;i&lt;length;i++) {         bits[i] = g.bits[i];     }    } }   The first constructor doesn't seem to be a "real" constructor, it seems as though in every case one of the other constructors will be used. So why is that constructor defined at all? A half covered lens Let's say there's an object in front of a convex lens. I have a piece of paper behind the lens at the right location such that it will the lens will form an image on the paper. The object is illuminating.  Now if I put another piece of paper right before the lens, and cover up half of the lens. The image, instead of only half being visible, it will actually remain the same. The only difference is that it will be dimmer.  Now, the question is what if I remove the paper at the location where the image forms, and put my eye there. What will I see? Will I see the piece of paper which is blocking half of the lens at all? Does that mean I will just "see through" the paper?  I wanted to try this out myself, but unfortunately I don't have a lens besides me. Toggle Switch to swap the connections of two buttons I am trying to mod my arcade stick so I can switch two commonly swapped buttons on the controller.  Essentially they are simple 2 terminal momentary switches connected directly to the controller PCB. I would like to switch their responsibilities, so in my case the Back button and the LB button on the XBox pcb I would like to swap so the Back actuates the LB button on the PCB and the LB actuates the Back button.  My assumption is that I would need a switch with 8 terminals, 4 in 4 out.  What type of switch am I looking for? Why no file-name in Inode information? I know that symlinks have a separated inode from the original file and that they only point for the inode containing the data. My question is, where is the hardlink name stored if there's no field in the inode structure refering to "name". I know that this could be a a relatively easy question, but as all hardlinks have the same inode number i assume that no inode is created when creating a hard link. I have written an essay last year, as a personal exercise. I now have a course at uni on the topic and could basically just hand in this essay now, the topic fits perfectly. I have also never submitted this essay to any other course or so.  Could I just hand in this essay, or would I violate some rules with that? Is this maybe already self-plagiarism? How do I escape the wildcard/asterisk character in bash? For example:  me$ FOO="BAR * BAR" me$ echo $FOO BAR file1 file2 file3 file4 BAR   and using the \ escape character:  me$ FOO="BAR \* BAR" me$ echo $FOO BAR \* BAR   I'm obviously doing something stupid.  How do I get the output BAR * BAR? I’m having trouble finding an official clarification of this, so I’m wondering if anyone has found a ruling:  Solarians gain powers known as stellar revelations. These are either “photon” or “graviton” revelations. It is specifically mentioned they can be used out of combat, though most include improved effects or separate powers that can only be used “while attuned” - a state a Solarian enters during combat. They may be photon or graviton attuned, at the player’s choice, and are able to increase their level of attunement each round until they become fully attuned to one or the other. However, apart from the very powerful “zenith revelations”, nowhere in the rules mentions whether photon revelations may only be used while photon attuned, or graviton revelations only while graviton attuned. The revelations themselves usually say “while attuned or fully attuned” for the more powerful effects, without mentioning the mode, and there’s no general rule in the class feature that answers this question.  Is there an official ruling on whether the “only while attuned” power of a photon revelation can be used when the character is graviton attuned, or vice versa? I suspect the answer is yes but it’s hard to tell based on the core rules. I am confused by the orientation of a topological manifold. My understanding is: An orientation of a topological manifold is a choice of generator of the $H^n(M,\mathbb Z)$. So given a manifold, we could have 2 orientation defined on the manifold. For $\mathbb{CP}^2$ on orientation is determined by the complex structure, the other orientation is denoted by $\overline{\mathbb{CP}}^2$. And it is well known that there is no orientation reversing map from $\mathbb{CP}^2$ to itself.  My question is: are they homeomorphic? I guess they are not homeomorphic. But I am confuesed, doesn't the orientations defined on the same manifold, how come after reversing the orientation they become not homeomorphic?