Server refused our key (AWS) - Putty
Non-root login on EC2 instance
This question relates to a discussion on . Euclid's proof of the infinitude of primes is an indirect proof (a.k.a. proof by contradiction, reductio ad absurdum, modus tollens). My understanding is that Intuitionists reject such proofs because they rely on the Law of the Excluded Middle, which they don't accept. Does there exist a direct and constructive proof of the infinitude of primes? I have really no idea about this:  Problem: Show that there exists a function $f:[0,1]\rightarrow\mathbb{R}$ such that:  $f$ is discontinuous in all $x\in \mathbb Q$. $f$ is increasing in $[0,1]$. $f$ is integrable.   EDIT: Sorry, it is not discontinuous in all $x\in \mathbb R \setminus \mathbb Q$, just in $\mathbb Q$. Automatically solve dependencies of deb packages while using dpkg -i Installing Deb packages on the command line, using dpkg -i, only installs the package in question and displays errors of unresolved dependencies (manually solved by apt-geting the packages it complains about). How do I automatically resolve dependencies when installing standalone packages? How to change css property using javascript Downloading files using wget I am trying to download files from .  The URL is:   When I use this command:  wget http://www.ncbi.nlm.nih.gov/geo/download/?acc=GSE48191&amp;format=file    I get only index.html?acc=GSE48191 which is some kind of binary format.  How can I download the files from this HTTP site? Programmatically, how does "rooting" a device enable access? Balloons and lifting gases Hydrogen is the lightest element, so it's cable of lifting the most weight in out atmosphere (probably not the best terminology there, but you get the picture)  Would hot hydrogen (in the same sense as hot air) be able to lift even more mass? Would a higher or lower density of hydrogen in a ballon lift more? If you could have a balloon which had nothing in it (it was a vacuum inside) would that lift more than a hydrogen balloon?  Basically what are the physics to balloons and lifting?  (really not sure what to tag this, so if someone else could that'd be great) In Windows 10 how can we change the name of this folder under C:\Users? I'm using Windows 10 on my personal computer (HP Pavilion Laptop) and you can see in the Screen Shot under C:\Users there are two folders.    The name of the first folder is C:\Users\SINGHA, however, the correct spelling of my last name is SINHA.  I need to change the name of this folder to C:\Users\SINHA so that it shows the correct name.     Under User Account, the spelling of my name is correct - it's only under C:\Users\ where the name is spelt incorrectly. Consequently, if I open/edit a Word or Excel document, the name of the owner being shown is the incorrect one (i.e it's shown as C:\Users\SINGHA instead of C:\Users\SINHA)   If I right-click on this folder, I won't get the Rename option; How can I change the name of this folder? I have the following configuration, but I have not able to find any documentation on how to set a maximum backup files on date rolling style.  I know that you can do this with size rolling style by using the maxSizeRollBackups.  &lt;appender name="AppLogFileAppender" type="log4net.Appender.RollingFileAppender"&gt;     &lt;file value="mylog.log" /&gt;     &lt;appendToFile value="true" /&gt;     &lt;lockingModel type="log4net.Appender.FileAppender+MinimalLock" /&gt;     &lt;rollingStyle value="Date" /&gt;     &lt;datePattern value=".yyMMdd.'log'" /&gt;     &lt;layout type="log4net.Layout.PatternLayout"&gt;       &lt;conversionPattern value="%d %-5p %c - %m%n"  /&gt;     &lt;/layout&gt; &lt;/appender&gt; Accessing Email logs using REST or SOQL Django set default form values I have a Model as follows:  class TankJournal(models.Model):     user = models.ForeignKey(User)     tank = models.ForeignKey(TankProfile)     ts = models.IntegerField(max_length=15)     title = models.CharField(max_length=50)     body = models.TextField()   I also have a model form for the above model as follows:  class JournalForm(ModelForm):     tank = forms.IntegerField(widget=forms.HiddenInput())       class Meta:         model = TankJournal         exclude = ('user','ts')   I want to know how to set the default value for that tank hidden field. Here is my function to show/save the form so far:  def addJournal(request, id=0):     if not request.user.is_authenticated():         return HttpResponseRedirect('/')      # checking if they own the tank     from django.contrib.auth.models import User     user = User.objects.get(pk=request.session['id'])      if request.method == 'POST':         form = JournalForm(request.POST)         if form.is_valid():             obj = form.save(commit=False)              # setting the user and ts             from time import time             obj.ts = int(time())             obj.user = user              obj.tank = TankProfile.objects.get(pk=form.cleaned_data['tank_id'])              # saving the test             obj.save()      else:         form = JournalForm()      try:         tank = TankProfile.objects.get(user=user, id=id)     except TankProfile.DoesNotExist:         return HttpResponseRedirect('/error/') What is the difference between test set and validation set? How can I find out the variable name in python? I know how I can find out the python command by clicking a button in the Blender interface, and then look in the info window:   For example, as can be seen, I added a cube, UV sphere, plane, camera, lamp, pressed A twice.  But how can I find out an object variable name, for example the y-rotation of an object. Because I can't find the y-rotation, when I point my mouse over it, I can only find the rotation: How do I find a command if I don't know its name? Explaining to an 8-year-old why nothing can travel faster than light Why is "glide symmetry" its own type? Artin's Algebra pages 155 &amp; 156 list the types of symmetry of a plane figure as:   Reflective Rotational Translational Glide   He then goes on to say "Figures such as wallpaper patterns may have two talk about other figures having combinations of independent" symmetries. EDIT: He says "... having combinations of independent translational symmetries". See Joriki's answer.  Why doesn't glide symmetry count as having two independent (reflection + translation) symmetries? If we're going to count combinations, why not have rotation + translation etc. as their own types too? style=apa causes bibliography to fail Entire one-to-one functions are linear Can we prove that every entire one-to-one function is linear? Are other players able to see you on their map in Pokemon Go? I am concerned that if I use the game, stalkers and other such people would be able to find me. I have searched for an answer for this question on other forums, but have yet to find the answer. What's better here - a single column or multicolumn primary key? Let's assume you have a table groups and a table item. Each item belongs to exactly one group. It is an inherent part of that group. An item cannot exist outside of a group and it cannot be moved to another group.  When trying to decide on a primary key for the item table, what should I use?  Should I make up an artificial global serial key like this:  CREATE TABLE items (     item serial PRIMARY KEY,     group integer NOT NULL REFERENCES groups(group), );   ... or should I rather use a composite key and per-group item serial like this:  CREATE TABLE items (     group integer NOT NULL REFERENCES groups(group),     item integer NOT NULL,      PRIMARY KEY(group, item) );   The reason why I'm leaning more towards the second solution is that the post URL will always show the group and item, so it makes sense to have both of them as the composite primary key. In case of the first solution, the URL contains superfluous information because the group ID can already be deduced from the item ID alone. The URL structure is given, however, and cannot be changed.  The disadvantage of the second solution is that you have to manage a per-group serial (i.e. each item integer should start from 0 for each group).  What's better in terms of best practices, normalization and performance? Or is it simply a matter of taste?