I'm so new to Linux and suddenly found the error message appear when i boot after i click install ubuntu  Kernel Panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,2)
Upon trying to upgrade from 10.10 to 11.04 all seemed to go well until the restart. This error message is what comes up:  Kernel Panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)   How do we fix that?
I am wondering what the difference between a definition and an axiom.  Isn't an axiom something what we define to be true?  For example, one of the axioms of Peano Arithmetic states that $\forall n:0\neq S(n)$, or in English, that zero isn't the successor of any natural number. Why can't we define 0 to be the natural number such that it isn't the successor of any natural number?  In general, why is an axiom not a definition?   Are there cases where we can formulate definitions as axioms or vice versa? Local TLD vs. .com and .com/nl vs .nl I basically have 2 questions about local TLD vs .com.  First question: There already exists a website "keyword.nl" with a crappy website, no SEO optimisation. Is it possible for a website "keyword.com" to rank higher than the "keyword.nl" website on "google.nl" when searching for "keyword"? Or will it always display the .nl website higher because it's a local TLD and the URL consists entirely and only from the searched keyword and it's searched on the .nl version of google?  Second question: I know it's good for SEO to have many websites link to your website. But I also read that local TLD's will score higher on that specific google TLD (.fr website will rank higher in google.fr, etc.) With both those facts in mind, is it better to create a "keyword.com/fr/" and "keyword.com/nl/" website or a "keyword.fr" and a "keyword.nl" website? (In other words, .com/langauge for more links to the website, or a "keyword.local-TLD" website for every different language version of the website) Or maybe even a subdomain? ("fr.keyword.com?")  Kinda new to this, so thanks in advance!  --Edit: additional info--  The reason that I phrased the original question like this is because I wanted to keep the question strictly "webmaster-side". However I feel like maybe I should clarify the background of this question more thoroughly, so the question becomes more clear, and thus the answer. But I don't know if this would make the question a more legal one instead of a "webmaster" one, so please correct me if this is the wrong place to post this question.  I'm a student working on websites in my sparetime, I have basic knowledge about SEO, but that was all local, for companies operating only in one country. However this time a friend contacted me who wants to found a company called "X" (e.g). He wants to ship/operate to multiple countries, but he will first found it (and he himself) lives in The Netherlands (.nl). However there already exists a company in The Netherlands called "x" with the website "x.nl". As far as I understood, the fact that both the companies are called "x" doesn't matter, in trademark/company registery terms, since they are both operating in different work sectors.    But the main issue here is, could my friends website "x.com/nl" outrank the "x.nl" on "google.nl" if you only search on the brand name; "x"?  @Closetnoc:  Hi, thanks a lot for your answer, it gave me some clarification however I feel you misunderstood my first question because of my use of "keyword.com" as an example URL. So I don't really know what conclussion I should draw from your first answer. I updated my question with additional info to clarify it more broadly. From your second answer this is what I understand: A .nl URL will not do that great on google.com, however a .com URL can do just as well as a .nl search on google.nl? So considering the info above, it's best to go with a x.com/fr and a x.com/nl URL, right? Please correct me if I misunderstood. However, if so, that still leaves the first question, if a "x.nl" is already taken, could a "x.com/nl" still outrank it at "google.nl"? This is an example from a question sheet (non-assessed) of a university class. If M is a non-orientable, closed, connected 3 manifold, prove $H_1(M;\mathbb{Z})$ is an infinite group. I know that since $M$ is non-orientable it follows that $H_3(M;\mathbb{Z}) = 0$ and since $M$ is connected $H_0(M;\mathbb{Z}) = \mathbb{Z}$. I want to apply a combination of Poincare duality and Universal coefficient theorem to try and find a contradiction if $H_1(M;\mathbb{Z})$ has no free part. However poincare duality doesn't apply here so I'm stuck.  I would appreciate any hints as to how to proceed. Match-3 algorithm to fill empty space left from removing matches I am currently creating a match 3 game.   I am at the point where I have objects dropping down in the column when only one item is removed. So if an item is removed, the above item moves into its old position etc.  The problem I am having now is that when more than one item is removed from a column, the items in that column only drop down to the first item that was removed. Instead of filling in both items that were removed it just drops down to fill in the first one.   So basically, if two(or more) items are removed from a column the second, third, fourth, etc positions are left blank.  The way I am designing my game is I am using units of 1. So each item takes up 1 unit by x and 1 unit by y. This means that I can position the items like in a grid, at 0x1, 0x2, etc.   What kind of algorithm could I use to move multiple items down to fill the empty space? Suppose that $\hat{x}$ is the least squares solution of $Ax = b$.  That is, $\min{|r|}, r = Ax - b$ with respect to $x$.  Is $\hat{x}$ also the least squares solution of $JAx = Jb$?  I suspect so, but I'm not sure how to prove it.  If $J$ is invertible, it's easy enough to prove as you can just cancel it out from both sides.  But what if it's not invertible? How long would the conference be for? I want to know if this is grammatically correct " How long would the conference be for?". Why don't we pluralize "foot" in measurements? I am in the last year of MSc. and would like to read string theory. I have the Zwiebach Book, but along with it what other advanced book can be followed, which can be a complimentary to Zwiebach. I would like a more mathematically rigorous book or lecture notes along with Zwiebach.   Specifically, mention whether the book discusses string theory   Rigorously? Intuitively?   What's the scope of the book? Does it cover the advanced materials, e.g. Matrix string theory, F-theory, string field theory, etc. Maybe even String Phenomenology? When I log in with LightDM on my laptop running Debian Unstable, it recently started to hang for around 2 minutes until journalctl shows the message kernel: random: crng init done. When I press random keys on my keyboard while it hangs, it logs in faster (around 10 seconds). Before I didn't have this issue, is there any way I can fix it?  Edit: using linux-image-4.15.0-3-amd64 instead of linux-image-4.16.0-1-amd64 works, but I don't want to use an older kernel. What's the scope of a variable initialized in an if statement? Sample size for logistic regression? I want to make a logistic model from my survey data. It is a small survey of four residential colonies in which only 154 respondents were interviewed. My dependent variable is "satisfactory transition to work". I found that, of the 154 respondents, 73 said that they have satisfactorily transitioned to work, while the rest did not. So the dependent variable is binary in nature and I decided to use logistic regression. I have seven independent variables (three continuous and four nominal). One guideline suggest that there should be 10 cases for each predictor / independent variable (Agresti, 2007). Based on this guideline I feel that it is OK to run logistic regression.    Am I right? If not please let me know how to decide the number of independent variables? What is the point of the `cd` external command? How can I randomise the output of a redstone circuit? I frequently cross this issue, and always have to google for an answer. Does anyone have a permanent fix for BADSIG errors from apt-get?     W: GPG error:    lucid   Release: The following signatures were   invalid: BADSIG 54422A4B98AB5139   Oracle Corporation (VirtualBox archive   signing key) Do I need quote marks when I quote myself? Index notation Lorentz transfromation matrix Why does Google not consider dot in usernames of Gmail addresses? E.g.: If your Gmail ID is abc.xyz@gmail.com, it considers this the same as abcxyz@gmail.com.  Why is this so? Shortest path from points in one layer to points in another layer via roads in QGIS What's the difference between Normalization and Standardization? Laptop w/o battery US bound flight?