I have installed Ubuntu 20 in a seperate partition of disk , however after ubuntu installation i can only boot up ubuntu , its not giving me any options to choose the OS. Using Dell Vostro. THanks in advance
I installed Windows on my computer, followed by an installation of Ubuntu. However, now I'm unable to boot into my Windows install.  What can I do to fix this?
Should you use "who" or "that" when talking about multiple people doing something? Which of the following is correct?        There were 10 people that went to the store.   There were 10 people who went to the store.      Edit:  Which of the following is correct?        There were 10 people that had brown hair.   There were 10 people who had brown hair. Say I have an embedded device which is only capable of doing HMAC-SHA1 transformations (that device is, in fact, a YubiKey).  Would it be secure to feed it like a block cipher in counter mode to get a random pad suitable as an stream cipher?  Of course, I'm talking about not repeating the counter value ever to encrypt data (so this construction would also need some random IV or treating the counter value as a nonce forever). Problem: James has a pile of n stones for some positive integer n ≥ 2. At each step, he   chooses one pile of stones and splits it into two smaller piles and writes the product   of the new pile sizes on the board. He repeats this process until every pile is exactly   one stone.      For example, if James has n = 12 stones, he could split that pile into a pile of size   4 and another pile of size 8. James would then write the number 4 · 8 = 32 on the   board. He then decides to split the pile of 4 stones into a pile with 1 stone and a   pile with 3 stones and writes 1 · 3 = 3 on the board. He continues this way until he   has 12 piles with one stone each.      Prove that no matter how James splits the piles (starting with a single pile of n   stones), the sum of the numbers on the blackboard at the end of the procedure is   always the same.   Hint: First figure out what the formula for the final sum will be. Then prove it using strong induction.  The formula I came up with is $n(n-1) / $2. It could be totally wrong...  My (Partial) Solution:  1) Base Case: (n=2) James has one pile of 2 stones. Suppose he takes the top-most stone and puts in one pile A, which now has size 1. He takes the remaining stone and places it into another pile B, which now has size 1. Then the product of the sizes is 1. The sum of all the products on his board is 1. Now, if he were to start again, and take the bottom stone first and put it in pile A, he has a pile of size 1, and then takes the top stone and puts it in pile B, he has a pile of size 1, and the product is 1, with sum of all products on the board is 1.   2) Inductive Hypothesis (Strong Induction): Suppose for some $k \geq 2$, $n$ stones can be split in $ 2 \leq n \leq k $ stones and $k-n$ stones.  3) Inductive Step:  Consider $n=k+1$. What do I do now? Are employments in universities affiliated (or named) with a specific religion restricted to people with the same religion? I just saw an ad in mathjobs.org about an opening in a Catholic university, see . I am not christian. So I was wondering to be eligible for employment in a university or college affiliated with a specific religion, should the applicant  have the same religion, or other people from other religions (or even non-religious people) are eligible to apply as well? The problem is this:      Suppose $I \subseteq R$ is a nilpotent ideal and there is $r \in R$ with $r \equiv r^2 \pmod I$. Show $r \equiv e \pmod I$ for some $e \in R$ idempotent.   I have spent a few hours rolling around in abstracta with no destination. I believe that if I could write down a concrete example of this, the example could guide me through the abstract definitions and show me where to look for an idempotent in $R$. I have looked at 2x2 matrices and could not find any such examples. Might anybody have one? $m$ is a perfect square iff $m$ has an odd number of divisors? I recently moved from having a main site like www.example.com with a subdomain associated site yyy.example.com, to moving everything off the subdomain to a subdirectory like www.example.com/yyy/, with the same hierarchy underneath the subdirectory, and now yyy.example.com is just a redirect page to the subdirectory, so yyy.example.com/abc/page-x is redirected to www.example.com/yyy/abc/page-x and so on.  The effect has been that the traffic increased by several times (the total page views are more than ten times at the present rate) what it was to the yyy subdomain. Previously almost all of the traffic to the yyy subdomain was from the www site. This is from monitoring the old yyy site for a year or more.  I'm curious to know if there's any research or results which would indicate whether this is universal (subdirectories beat subdomains) or "just me". Can I create a user-specific hosts file to complement /etc/hosts? Is it possible to add a list of hosts that are only specific to a certain user? Perhaps a user-specific hosts file?  This mechanism should also complement the entries in the /etc/hosts file. Find Orthogonal complement I was looking for proofs using Calculus for the area of a circle and come across this one $$\int 2 \pi r \, dr = 2\pi \frac {r^2}{2} = \pi r^2$$  and it struck me as being particularly easy. The only other proof I've seen was by a teacher and it involved integrating $x = \sqrt{r^2 - y^2}$ from $-1$ to $1$, using trig substitutions and then doubling the area to get $\pi r^2$ but the above proof seemed much more straight forward.  Is it a valid proof, or is it based on circular logic or some other kind of fallacy? MSO Review Queue Privileges are Misleading When I visit Stack Overflow, I see the review option in the bar at the top of the screen.    However when on MSO, I don't see it. I assumed this was because I didn't have enough reputation to access the queue. I was curious what the requirement was on meta, so I moseyed on over to the privileges page. To my surprise, I saw that the privilege is listed as only requiring 500 rep and informs me I already have it:    Confused, I manually typed in meta.stackoverflow.com/review to see what would happen. The page did in fact load, but as you can see meta has no "First Posts" or "Late Answers" queue.    Seeing on that page that a minimum of 2k reputation is required to access any queues on MSO, I report the following bug:  1) On the privileges list on MSO, the 500 rep privilege of "Access first posts and late answers review queues" should not appear.  I also have the following feature request:  2) On the privileges list on MSO, it would be useful if instead there was a 2k privilege that informed you that you have access to the "Suggested Edits" and "Low Quality Posts" queues. Some GUI apps use OS X location services, but I want to retrieve a Mac's physical location from the . This could be useful for running scripts, switching settings etc. The mechanism should be , not a Geo IP service (data too low-res, needs online connection).  Minimum requirement is output of longitude and latitude. Nice would be a number indicating the precision. Super nice: a geocoder that provides location names. How did Harry, Ron and Hermione buy presents for each other? I have been re-reading the Harry Potter books again and I noticed that Harry, Ron and Hermione have been giving each other Christmas presents each year at Hogwarts. How have they been able to buy each other presents if they are not allowed to go out of Hogwarts?   From their third year on they could visit the village and buy presents there, but what about the first two years? Did they give their personal belongings? Or did they just happen to have boxes of chocolates or books to give each other? Concatenate table without header I would like to concatenate several tables and just keeping the header in the first line (and thus not having a new header each time that a new table has been concatenate). Does anyone know how to do that?  I am currently using:  find "/dir/folder" name "*.dat" -exec cat {} + &gt;&gt; "/dir/folder/table.txt"   but I can get rid of the header with that. Indefinite articles used with plural nouns: It was AN amazing TWO DAYS The indefinite article a(n), derives from the old English word an meaning "one". Generally this word only occurs in determiner function before noun phrases which are singular. However, there seem to be some cases where this determiner occurs before plural noun phrases. I say that, but actually these noun phrase seem so bizarre to me, in terms of their structure, that I'm not sure they're definitely noun phrases at all. Here are some examples:   a full three months before we left an amazing two days an awkward ten minutes   Ignoring the article here for a moment, these noun phrases are odd because the adjective is occurring before the numeral. We would normally expect to see:   three full months two amazing days ten awkward minutes   Even given the oddness of the word order in the original phrases, I can see no reason why the normally singular indefinite article is licensed here.   Can anybody give an account of the syntactic structure of these phrases, and/or explain why the semantically singular article is able to be used with such phrases - even if they compulsorily trigger plural verb agreement?  Here is an example of one of these instances which seems to demand a plural verb:   An amazing two million people attend every year. *An amazing two million people attends every year. (ungrammatical) "thanks for flagging" popup gets messed up when the comment is automatically deleted For some comments, the comment is automatically deleted when you raise a flag. This includes certain keywords and short +1 comments. But when you raise that flag with the new comment flag interface, the "thanks for flagging" shows up in the top right when the comment is deleted:      As opposed to what happens when you raise a flag on a comment that doesn't auto-delete: I read somewhere that according to relativity, it is possible - involving black holes and other stuff - to jump into the past. Is it possible for anything to go back in time either continuously or by jumping? This is a homework problem for my real analysis class. It is problem 13.1 from Mattuck's Introdution to Analysis. The question reads:       Suppose F(x) is continuous on some open interval I and c is a maximum point inside this interval. Is it true that f(x) must be increasing immediately to the left of c and decreasing immediately to the right of c? Proof or counterexample. (Note: A constant function is considered to be both increasing and decreasing.)      My friend and I have been attempting to find a counterexample. We figured a function that begins oscillating infinitely many times near c but converges to c would work. We're having difficulty constructing such a function out of elementary functions so we think we will have to define it in another way, piece-wise using receding intervals. I have no clue how this would look. Any advice would be greatly appreciated. How can I ensure testNG test method does not abort if any assert fails I know there is a difference between assert and verify in Junit; the assert results in a runtime exception, causing test method execution to abort. To overcome this problem, we can have verify which will make test case fail, but allowing test execution to proceed rather than getting aborted.  I doubt there is any such built in approach in testNG. I do understand that best practices say, there should not be multiple asserts in same test case.  But, in practical world, we do come across scenarios where we need to have multiple checkpoints in one test case and we don't want our test method to abort because of one check point failure (test execution should proceed despite failure).  How can we use a soft assert mechanism, similar to verify, which will not abort test method when there is a checkpoint failure.  Example:  @Test(dataProvider = "getMailUrl") public void testMail(email,subject); Assert.assertFalse(subject.isEmpty);//1st checkpoint Assert.assertNotNull(email); //2nd checkpoint Assert.assertEquals(email, "feedback@yoursite.com"); //3rd checkpoint   Now, I want test execution to proceed, even if the 1st checkpoint (validation of subject being not empty) fails. Definitely we will be not be using assert (hard assert). We will need concept of soft assert similar to verify (facilitated by Junit).   I understand, we have to build a customListener implementing TestNG interfaces or extending existing listeners such as TestListenerAdapter. I am still struggling - how can we do this? Are the square roots of all non-perfect squares irrational?