Data Recovery after installing Ubuntu
How do I recover my accidentally lost Windows partitions after installing Ubuntu?
There should be infinitely many primes of the form $5+6n$. How do you prove it? The same should be true for $7+6n$. I was wondering this today, and my algebra professor didn't know the answer.      Are subgroups of finitely generated groups also finitely generated?    I suppose it is necessarily true for finitely generated abelian groups, but is it true in general?  And if not, is there a simple example of a finitely generated group with a non-finitely generated subgroup?  NOTE:  This question has been merged with another question, asked by an undergraduate.  For an example not involving free groups, please see Andreas Caranti's answer, which was the accepted answer on the merged question. Key Presses in Python Collinearity can pose certain problems in various kinds of regression problem. In particular, it can make the parameter estimates have high variance and be unstable.   Various methods have been proposed to deal with this including ridge regression, partial least squares regression, principal components regression, dropping variables and getting more data.   One method that is controversial is standardizing or scaling the independent variables, with various experts saying it is a good (e.g. Garcia) or bad (e.g. Belsley) idea. Belsley's issue seems to be (in non-technical terms) that changing the IVs just pushes the problem under the rug.  But other experts seem not to agree. And the authors tend to get rather heated in defending their own positions.   Back when I did my dissertation (on collinearity diagnostics) I found Belsley's arguments convincing, but that was long ago (I got my degree in 1999).  I'm looking either for expert guidance or for any current review article that is unbiased. Blowing your own sail? How it this possible? Even if the gif is fake, the Mythbusters did it and with a large sail it really moves forward. What is the explanation? How do I make a floor plan with specific dimensions? Possible Duplicate:           What book would you recommend for an undergraduate wanting to learn the basics of topology? I've come across several books that claim to give an introduction to the subject, but I wasn't sure which one(s) to pick.  Here are some of the books I came across:   Introduction to Topology - Bert Mendelson Basic Topology - M.A. Armstrong First Concepts of Topology - William G. Chinn Topology Without Tears - Sidney A. Morris Topology - James Munkres   They don't go over the exact same topics, some are more in-depth than others, some seem to target slightly different audiences etc. What would be right for me (not necessarily from that list)? To give some more background, I want to learn topology because I feel it will be somewhat helpful in the field of Computer Vision. What is the logarithm of a kilometer? Is it a dimensionless number? In log-plots a quantity is plotted on a logarithmic scale. This got me thinking about what the logarithm of a unit actually is.  Suppose I have something with length $L = 1 \:\mathrm{km}$.  $\log L = \log \mathrm{km}$  It seems that the unit of $\log L$ is $\log \mathrm{km}$, but I can also say $L = 1000 \mathrm{\:m}$ and now:  $\log L = 3 + \log \mathrm{m}$  This doesn't appear to have any units at all.  This suggests that $\log \mathrm{km}$ and $\log \mathrm{m}$ are actually dimensionless numbers. But wait, I can do this with any unit! Does it actually make sense to talk about the logarithm of a unit, or some other function for that matter? What TV movie had lost space cadets who piloted yellow tripod robots, and a squid bad guy? I'm trying to find a movie I watched on TV, probably in the 90s. I think it was a made-for-TV movie.  It was about a ship with an AI. The ship was crewed by young adults. I think they were cadets?   There was an accident (like a warp drive malfunction) and they end up in another part of space where they meet a female alien whose ship had been shot down.  I remember they had manned robots they would pilot and they took them to a planet to get upgraded and they are attacked by more manned robots. They had three legs and they were yellow, I think.  I also remember the baddie had a holo-projector or something like that which allowed him to change his appearance. He commanded a massive fleet and he worked for someone he spoke to in a video chat that looked like a squid. Can't find boot-repair package for the newest version of Ubuntu Using InDesign CS6, how can I simultaneously edit A4 and A5 versions of a poster? I'm on Adobe Creative Cloud, so I have the latest InDesign, and I'm attempting to design a poster for my choir's next concert. Traditionally, I've done this in Photoshop, in two separate files, however I've recently started using InDesign after converting to it to create wedding albums through Blurb.  I've created an A4 document, and created an alternate-layout for it in A5. I've then lined them up side-by-side, and I've added a black frame to the A4 page, to act as the black background for my page (by the way, feel free to advise on better ways to do this).  My assumption is that I've failed to understand how this works, as I was hoping that I'd magically get a black frame on the A5 version, and that I could use liquid layout to get this to automatically scale (along with all other elements), in order to create the two versions simultaneously.  All help/advice would be greatly appreciated! What evidence is there supporting an alternative parentage for Jon Snow? I've heard speculation that Jon Snow's actual parents may be Rhaegar and Lyanna Stark, but in reading the books I'm not sure what evidence could be used to support this conclusion.  I thought there might have been something in the conversation Davos had before being smuggled into White Harbor, but I couldn't stretch anything that far.  What evidence do proponents of this theory cite?  Does any of it involve stuff in the texts or just sweeping generalizations of the characters' personalities (e.g. "Ned Stark is too honorable to father a bastard"). How to give an image or video a TV screen effect? Are neutrinos affected by electromagnetic forces? I know they don't interact with matter nor any electromagnetic forces, but I know they have mass, very little mass but they have. When something has mass it must be attracted by gravity and other objects (electromagnetic) right? Show inline math as if it were display math (and vice versa) I'm very familiar with how symbols display differently in inline mode (with $ ... $) vs. how display math shows them (with \[ ... \] or $$ ... $$).  Two examples would be with limits  $\lim_{n\rightarrow \infty}f(x)$   vs.  \[ \lim_{n\rightarrow \infty}f(x) \]   and with sums  $\sum_{n=1}^{x} n^2$   vs.  \[ \sum_{n=1}^{x} n^2 \]   My Question is:     How do you display these things in inline mode (with all the nice inline formatting) as if they were in display mode ?   The inverse -- how to display things in display mode as if they were in inline mode -- is also of interest. Update: Failed to lock /var/cache/apt/archives/lock I am running the upgrade(12.10 to 13.04) through terminal and it keeps getting stuck at this:  Failed to lock /var/cache/apt/archives/lock   What do I do? I have root access. I have no idea what else to try other than a clean install.  Checking package manager Reading package lists... Done     Building dependency tree           Reading state information... Done Building data structures... Done   Calculating the changes Calculating the changes  Do you want to start the upgrade?   3 packages are going to be removed. 155 new packages are going to be  installed. 1204 packages are going to be upgraded.   You have to download a total of 595 M. This download will take about  1 hour 15 minutes with a 1Mbit DSL connection and about 23 hours with  a 56k modem.   Fetching and installing the upgrade can take several hours. Once the  download has finished, the process cannot be canceled.    Continue [yN]  Details [d]y  Fetching  Could not download the upgrades   The upgrade has aborted. Please check your Internet connection or  installation media and try again. All files downloaded so far have  been kept.   Failed to lock /var/cache/apt/archives/lock    Restoring original system state  Aborting Reading package lists... Done     Building dependency tree           Reading state information... Done Building data structures... Done  root@chaitanya-XPS-Ubuntu:~# Can I use Wilcoxon Signed-Rank Test to test pairs of data in a time series? I have a dataset of measurements (non-normally distributed). Each line of this dataset is composed of two measurements of the same variable at a specific time (i.e. XYY [time, meas1, meas2]). This dataset contains 24 lines.  Is it correct to use the Wilcoxon Signed-Rank Test to compare these two measurements? Is it correct to use this test to compare the mean value of these measurements between different experiments?  Thanks I have a NOPASSWD line in /etc/sudoers (edited with visudo)  gatoatigrado    ALL=(ALL) NOPASSWD: /bin/set-slow-cpufreq   However, the output is,  gatoatigrado@coral:~&gt; sudo -n /bin/set-slow-cpufreq sudo: sorry, a password is required to run sudo   This kind of command works on an OpenSuSE machine, but not on Ubuntu 11.10. What am I doing wrong?  Note: I cannot find any relevant system log messages, e.g. via tail -f /var/log/syslog.  edit  Here is /etc/sudoers.  Defaults    env_reset  # things I've tried copying from an opensuse machine Defaults always_set_home Defaults env_keep = "LANG LC_ADDRESS LC_CTYPE LC_COLLATE LC_IDENTIFICATION LC_MEASUREMENT LC_MESSAGES LC_MONETARY LC_NAME LC_NUMERIC LC_PAPER LC_TELEPHONE LC_TIME LC_ALL LANGUAGE LINGUAS XDG_SESSION_COOKIE"  root    ALL=(ALL:ALL) ALL gatoatigrado ALL=NOPASSWD: /bin/set-slow-cpufreq %admin ALL=(ALL) ALL %sudo   ALL=(ALL:ALL) ALL How can I have  for Ubuntu? I am trying to automate various tasks in ArcGIS Desktop (using ArcMap generally) with Python, and I keep needing a way to add a shapefile to the current map. (And then do stuff to it, but that's another story).  The best I can do so far is to add a layer file to the current map, using the following ("addLayer" is a layer file object):  def AddLayerFromLayerFile(addLayer):  import arcpy  mxd = arcpy.mapping.MapDocument("CURRENT")  df = arcpy.mapping.ListDataFrames(mxd, "Layers")[0]  arcpy.mapping.AddLayer(df, addLayer, "AUTO_ARRANGE")  arcpy.RefreshActiveView()  arcpy.RefreshTOC()  del mxd, df, addLayer   However, my raw data is always going be shapefiles, so I need to be able to open them. (Equivalently: convert a shapefile to a layer file without opening it, but I'd prefer not to do that).