Can't boot into Windows 10 from GRUB menu, even though the option of Windows 10 is there?
Unable to boot into Windows after installing Ubuntu, how to fix?
Natural deduction, Proof $\vdash$ $P\Rightarrow(Q\Rightarrow P)$ So I have a question regarding natural deduction, are we allowed to "copy" our previous assumption inside a new assumption. I will use an example to illustrate.  $\vdash$ $P\Rightarrow(Q\Rightarrow P)$  So here are my steps.  1.) $P$             Assumption  2.)$Q$             Assumption  3.)$P$             Copy (1)  4.)$Q \Rightarrow P$   Implication Introduction  5.)$P \Rightarrow (Q \Rightarrow P)$ Implication Introduction  Is my proof correct, or is there something missing. Equation of the locus of the foot of perpendicular from any focus upon any tangent to the ellipse ${x^2\over a^2}+{y^2\over b^2}=1$ Find the equation of the locus of the foot of perpendicular from any focus upon any tangent to the ellipse ${x^2\over a^2}+{y^2\over b^2}=1$. will it also be an ellipse? Uniform Scattering with vector Applying graduated renderer in PyQGIS? Just trying to run the following code already given in the pyqgis cookbook to create graduated colors symbology (as in example with 2 classes)  I define the source info for the shapefile but when I run execute the code within my test-plugin, it just adds the layer without classifiying. Just adds as usual, all polylines appear same.  Any solution or working code/method?  link to code in cookbook   from qgis.core import  (QgsVectorLayer, QgsMapLayerRegistry, QgsGraduatedSymbolRendererV2, QgsSymbolV2,QgsRendererRangeV2)  myVectorLayer = QgsVectorLayer('C:/my_test_shape_file.shp', 'test_shp_file', 'ogr')  myTargetField = 'target_field' myRangeList = [] myOpacity = 1  # Make our first symbol and range... myMin = 0.0 myMax = 50.0 myLabel = 'Group 1' myColour = QtGui.QColor('#ffee00') mySymbol1 = QgsSymbolV2.defaultSymbol(myVectorLayer.geometryType()) mySymbol1.setColor(myColour) mySymbol1.setAlpha(myOpacity) myRange1 = QgsRendererRangeV2(myMin, myMax, mySymbol1, myLabel) myRangeList.append(myRange1)  #now make another symbol and range... myMin = 50.1 myMax = 100 myLabel = 'Group 2' myColour = QtGui.QColor('#00eeff') mySymbol2 = QgsSymbolV2.defaultSymbol(myVectorLayer.geometryType()) mySymbol2.setColor(myColour) mySymbol2.setAlpha(myOpacity) myRange2 = QgsRendererRangeV2( myMin, myMax, mySymbol2, myLabel) myRangeList.append(myRange2)  myRenderer = QgsGraduatedSymbolRendererV2('', myRangeList) myRenderer.setMode(QgsGraduatedSymbolRendererV2.EqualInterval) myRenderer.setClassAttribute(myTargetField) myVectorLayer.setRendererV2(myRenderer) QgsMapLayerRegistry.instance().addMapLayer(myVectorLayer)      @Kelly's code works perfectly.   However I noticed that both the code (one I have typed in my first message and yours in the 2nd message) DO NOT work in QGIS v1.7.3 but WORKS in QGIS v1.8.0. I think this was a bug(?) that already resolved in v1.8.0  And one more question;  Do you have any sample code for (natural breaks, Jenks) classification of the "numeric_attribute_field" based on given number of classes (i.e. no of classes will be a variable in the code, say "n", and I will pass that from the plugin GUI i.e. n = spinBox.value() ) Deriving the Coulomb force equation from the idea of photon exchange? How do "pet" Walkers help ward off other Walkers? In both the comics and the show, Michonne first appears with two walkers that she essentially keeps as pets.    The comics sort of half-explain this - as per :     She notices walkers don't attack one another and hacks off the arms and lower jaws of Mike and Terry. She chains them up by their necks to use them as escorts for an escape that was successful.   In , we see that even if they still sort of smell like Walkers, the Walkers can smell/detect the living and will attack.  In ,      We see Andrea effectively making a new "pet" so that she can use to deter the Walkers that she comes across on her trip to the prison. Along the trip, she is shown to come within close range of Walkers, but they give her space when she points the "pets" in the right direction.   Why would the Walkers not just attempt to go around the "pets"? What about them creates an effective protective barrier? If $S$ is a nonempty subset of group $G$, then $S^{|G|}$ is a subgroup of $G$. Let $G$ be a group with $|G| = n$ and let $ \emptyset \ne S \subseteq G$.   I want to show that $S^n$ is a subgroup of $G$ where by $S^n$ I mean the set $\lbrace s_1\cdots s_n \; | \; s_i \in S\rbrace$. Using regex inside if clause in bash Look at this if block:  #!/bin/bash  str="m.m" if [[ "${str}" =~ "m\.m" ]]; then     echo "matched" else     echo "not matched"     exit 1 fi  exit 0   This should print "matched", but it doesn't. Where am I going wrong? Floating sidebar can get too long and obscure footer Sometimes, when you create a question which returns a lot of similar questions, it makes the height of the floating "Similiar Questions" box too big to fit on the page. As a result, it blocks some of the footer on the right hand side. It's actually doing it as I type this question.  I think a max height based on the view port - footerHeight should fix it. xdg-open on debian 9 fails to open browser I decided to try lxdm (was using fluxbox and xfce), and discovered that for many programs the url handler was failing, producing this error message;   Quite strange as you can see, it's prepending the user directory to the url.  The example here is from telegram, but it happens in discord, as well as when executing from the command line; xdg-open https://www.google.com produces a similar error. xdg-settings get default-web-browser output's firefox.desktop which works as a link in both xfce and lxdm.  More information; I ran bash -x on it and...  $ bash -x /usr/bin/xdg-open http://www.google.com + check_common_commands http://www.google.com + '[' 1 -gt 0 ']' + parm=http://www.google.com + shift + case "$parm" in + '[' 0 -gt 0 ']' + '[' -z '' ']' + unset XDG_UTILS_DEBUG_LEVEL + '[' 0 -lt 1 ']' + xdg_redirect_output=' &gt; /dev/null 2&gt; /dev/null' + '[' xhttp://www.google.com '!=' x ']' + url= + '[' 1 -gt 0 ']' + parm=http://www.google.com + shift + case "$parm" in + '[' -n '' ']' + url=http://www.google.com + '[' 0 -gt 0 ']' + '[' -z http://www.google.com ']' + detectDE + unset GREP_OPTIONS + '[' -n LXDE ']' + case "${XDG_CURRENT_DESKTOP}" in + DE=lxde + '[' xlxde = x ']' + '[' xlxde = x ']' + '[' xlxde = x ']' + '[' xlxde = xgnome ']' + '[' -f /run/user/1000/flatpak-info ']' + '[' xlxde = x ']' + DEBUG 2 'Selected DE lxde' + '[' -z '' ']' + return 0 + case "${BROWSER}" in + case "$DE" in + open_lxde http://www.google.com + pcmanfm --help -a is_file_url_or_path http://www.google.com ++ file_url_to_path http://www.google.com ++ local file=http://www.google.com ++ echo http://www.google.com ++ grep -q '^file:///' ++ echo http://www.google.com + local file=http://www.google.com + echo http://www.google.com + grep -q '^/' ++ pwd + file=/home/nesmerrill/.local/share/applications/http://www.google.com + pcmanfm /home/nesmerrill/.local/share/applications/http://www.google.com + '[' 0 -eq 0 ']' + exit_success + '[' 0 -gt 0 ']' + exit 0   The important part seems to be pcmanfm --help -a is_file_url_or_path http://www.google.com but, that command if that's how it was used, doesn't seem to do much of anything?  $ pcmanfm --help -a is_file_url_or_path http://www.google.com Usage:   pcmanfm [OPTION…] [FILE1, FILE2,...]    Help Options:   -h, --help                   Show help options   --help-all                   Show all help options   --help-gtk                   Show GTK+ Options  Application Options:   -p, --profile=PROFILE        Name of configuration profile   -d, --daemon-mode            Run PCManFM as a daemon   --no-desktop                 No function. Just to be compatible with nautilus   --desktop                    Launch desktop manager   --desktop-off                Turn off desktop manager if it's running   --desktop-pref               Open desktop preference dialog   --one-screen                 Use --desktop option only for one screen   -w, --set-wallpaper=FILE     Set desktop wallpaper from image FILE   --wallpaper-mode=MODE        Set mode of desktop wallpaper. MODE=(color|stretch|fit|crop|center|tile|screen)   --show-pref=N                Open Preferences dialog on the page N   -n, --new-win                Open new window   -f, --find-files             Open a Find Files window   --role=ROLE                  Window role for usage by window manager   --display=DISPLAY            X display to use Why do I have to say “want you to do” instead of “want you do”? I'm confused about 'want you to do (something)' and 'want you do (something)'.  Example:      "I want you to eat fish" instead of "I want you eat fish" or "I want that you eat fish".    Can anyone explain what is the grammar rule for this? Can I see things that I've said in chat that have been starred? I was reviewing the star on chat.SE list this morning and I noticed that quite a few of the items on the list were mine.  I was curious as to how often people enjoy the things I post there enough to star them, but I can't seem to find statistics about this anywhere.  Mana told me that no such feature exists.  (the best we could come up with is ) So here's my request - can I filter/search the chat history for things I've said that other people have starred? See dashboard as non logged user in community Is it possible, as a non logged user, to see report and dashboard in community when it is open to non logged user? And  for analytic dashboards? Scale Space Between Multiple Objects If I have multiple objects selected can I use scaling to make the objects closer together (without rescaling the objects)? I'm using the listings package with this \begin command:  \begin{lstlisting}[caption=blabla, label=amb]   This yields a nice code listing with a caption like "Listing 1.1 blabla". Is there a way to change the caption and have something like "Code 1.1 blabla"?  I saw the title command but it doesn't use a numbering system. Any hint will be greatly appreciated! I need to make this equation in LateX but I get some errors when i try to do that.    Can you help me please?? I'm running Bash scripting, but sometimes I get confused which of these commands I use belong to who. Sometimes man xxx works, sometimes doesn't, so I use --help or info, mostly one of these works to show description of the command. Can anyone tell me how I would know what command belongs to what? Bash builtin, GNU utility, etc. I recently upgraded to 12.04 from 11.10 and since upgrading have been unable to log in to my user profile. The upgrade went okay and I can login to a guest session fine but whenever I try to login to my profile, after entering my password, I just return to the login screen.  I've changed my password in Root (passwd &lt;username&gt;) and can log in to tty1 with no issues, it's just in GUI I'm having problems.  I'm using a HP dv7 laptop, 32-bit Ubuntu install, Intel® Core™2 Duo CPU P7350 @ 2.00GHz × 2, Nvidia graphics.  Any help would be appreciated. Fastest way to convert string to integer in PHP Plot $|z - i| + |z + i| = 16$ on the complex plane