Gregor Bruns
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 Nov15 answered Vakil's Foundations of Algebraic Geometry, Exercise 5.5.E Nov15 accepted Is there an extensive 'cheat sheet' for general topology questions? Nov15 asked Reading circle in mathematics? Nov15 awarded Fanatic Nov14 comment Approximation of $e$ by a rational number Yes, you can. Do you need to give such a number? Do you know about continued fractions? Nov7 comment Common sense in mathematics What do you mean by "mathematical method"? Does it include, e.g., finger counting? Where do "mathematical results" start for you? Oct20 comment Does Pi contain all possible number combinations? You should probably do it in the order of ascending length, not in alphabetical order, because you would never get beyond the sentences starting with 'A'. Oct20 asked Was there a culture/number system with negative numbers but without zero? Oct19 comment An 'easy' way to prove that epimorphism of sheaves implies surjectivity on stalks @ZhenLin: Thanks for your comment. I guess the general nonsense will have to do it for an elegant solution. It is not so difficult as I thought at first. If I want to have it more explicit, the longer solutions will still make visible where the surjectivity comes from. Oct19 asked Is there an extensive 'cheat sheet' for general topology questions? Oct1 awarded Citizen Patrol Oct1 asked An 'easy' way to prove that epimorphism of sheaves implies surjectivity on stalks Oct1 comment Does every prime ideal in a ring arise as kernel of a homomorphism into $\mathbb{Z}$? Only a minor comment: The first two sentences being in the same line makes them seem related, but they are not. Do you mind separating them (e.g. by an 'or')? Sep25 comment proof of chinese remainder theorem for ring Let $a_i + b_j = 1$. Multiply both sides by $x$, you get $xa_i+xb_j=x$. Now $xa_i$ is in $I$ and $xb_j$ is in $J$, because $I$ and $J$ are ideals. That is, for every $x\in R$ you get $x_i\in I$ and $x_j\in J$ such that $x_i+x_j=x$. Sep25 answered proof of chinese remainder theorem for ring Sep21 comment What is $dx$ in integration? @MichaelHardy: When I first studied calculus in university I found it incredibly confusing that people just talked about $\mathrm{d}x$ as if it was some kind of object or variable you can use in normal calculations. Especially the physicists did that when using the total derivative. It really makes no sense until you define every single operation correctly and no introductory textbook that I know of does this. So, for freshmen, the grammar explanation may help to avoid frustration (it did for me). Sep7 answered Doubts about fundamental theorem of Homomorphism Sep6 awarded Enthusiast Sep5 comment Splitting field and dimension of irreducible polynomials Do you know about the multiplicativity formula $[M:K]=[M:L][L:K]$ where $M|L$ and $L|K$ are field extensions? Sep5 comment Prove that there is no value of the integers $x,y,z$ satisfied the equation: $19^x + 5^y + 1980z = 1975^{4^{30}} + 2010$ @Vchau_VN: Please see my edit. Does that help?