Grigory M
Reputation
10,714
Next privilege 15,000 Rep.
Protect questions
 Apr5 reviewed Close How to show that an object is a discrete valuation ring? (Fulton, Exercise 2.14) Apr5 reviewed Close What is $2^{7!}\bmod{2987}$ Apr5 reviewed Close If $p,q$ are prime, solve $p^3-q^5=(p+q)^2$. Apr1 reviewed Close Let $R=\mathbb{Z}_2[X]$ and $I=$ then which of the following are in $I$? Mar31 comment Counter-example to exponential law for locally compact [non-Hausdorff] spaces @Stefan (Re: last comment) No-no, I want a counter example where X is not Hausdorff (and $Y$ is locally compact). Mar30 comment Counter-example to exponential law for locally compact [non-Hausdorff] spaces @user87690 Right, thank you (if one assumes a strong enough version of local compactness — for non-Hausdorff spaces there are different versions of the definition — one needn't assume that $Y$ is Hausdorff — I've updated the question). Mar30 revised Counter-example to exponential law for locally compact [non-Hausdorff] spaces deleted 123 characters in body Mar30 comment Counter-example to exponential law for locally compact [non-Hausdorff] spaces @johndoe ...And Sierpinski set is, perhaps, a good choice for $Z$ — AFAIR, there is some theorem along the lines 'if the exponential law hold for $Z=\text{Sierpinski}$ it holds for all $Z$'. Mar30 comment Counter-example to exponential law for locally compact [non-Hausdorff] spaces ...the idea of taking finite $X$ and $Y$ is quite tempting — because finite topological spaces are locally-compact (and I don't know many example of non-Hausdorff locally-compact spaces). I've tried to play with some examples — but haven't succeeded. Mar30 comment Counter-example to exponential law for locally compact [non-Hausdorff] spaces @johndoe Well, if either $X$, $Y$ or $Z$ is discrete the statement seems to be more or less obviously true. But slightly more generally... Mar30 comment Counter-example to exponential law for locally compact [non-Hausdorff] spaces Related (but not answering the question): @ n-Category Cafe Mar30 asked Counter-example to exponential law for locally compact [non-Hausdorff] spaces Mar21 comment Combinatorial definition of Hall–Littlewood polynomials (sum over SSYT?) @IgorMakhlin (И про t-версию Бриона и т.п. мы бы с М.Б. с интересом послушали в какой-то момент.) Mar21 comment Combinatorial definition of Hall–Littlewood polynomials (sum over SSYT?) @IgorMakhlin О, привет. Well, yes and no: there is an explicit description of the $t$-weight $\psi$ in Macdonald's book — but it's complicated and not terribly satisfying. So if you have a better answer, please explain it (here or iRL). Mar20 revised Algebraic tricks like componendo dividendo edited tags Mar12 comment Geometric interpretation for sum of fourth powers Well, yes, $1^k+2^k+...+n^k$ is the value of an Ehrhart polynomial for the 'hybercubic pyramid'. But does this help to compute the sum? Jan30 comment Is reduced homology a full functor on connected spaces? The question is about the category of connected spaces. Jan30 comment Is reduced homology a full functor on connected spaces? Uh? $\tilde H(pt)=0$. Jan23 reviewed Close In a group of order 21, every normal subgroup is cyclic Jan23 reviewed Close Separable spaces and functions that separate points