Sam Hopkins
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 Apr 28 revised Unique factorization of posets added 11 characters in body Apr 28 accepted Unique factorization of posets Apr 28 comment Unique factorization of posets Darij, those last two references answer my question perfectly: false in general, true when $P$ is connected. You could post it as an answer. Apr 28 asked Unique factorization of posets Apr 26 comment Is there an efficient algorithm to find all the maximum matching in any tree? The number of maximal matchings of a tree can be exponential in the number of edges of that tree, so it isn't exactly clear what could be meant by "efficient algorithm". Apr 19 comment Complete the following sequence: point, triangle, octahedron, . . . in a dg-category The hypersimplex is normally considered a two parameter family of polytopes: en.wikipedia.org/wiki/Hypersimplex. Can you say which hypersimplices we get? Apr 18 comment Notation clash between a representation and spectral radius Also in Lie theory isn't $\rho$ most commonly used for the half-sum of positive roots? Apr 15 comment Tableaux with limited rows and complementary skew shapes Huh, very interesting. Apr 15 comment Tableaux with limited rows and complementary skew shapes Can that last identity be seen as a consequence of the $S_3$-symmetry of the Littlewood-Richard coefficients $c_{\nu,\mu}^{\lambda}$? Apr 6 comment Missing citations of “to appear” papers on MathSciNet Is there any official email address/website for suggesting corrections to MR citations? Apr 5 answered Variants of Szemeredi's regularity lemma Mar 25 comment Paradoxical spherical caps @quid: Seems like that could be another tag that deserves a warning, then. Mar 20 comment Expert, Intuitive, Organizing Analogies So something like the analogy between number fields and function fields does not qualify (since both sides are mathematical)? Mar 13 comment Independence in mathematics Matroid theory was developed by Whitney as an abstraction of the notion of linear independence. See jstor.org/stable/2371182. Mar 13 comment Littlewood-Richardson rule for the complete flag variety: GapP complete? @MattSamuel: But as you point out, the problem being GapP-complete is morally equivalent to it being impossible to find a Littlewood-Richardson rule. So presumably it would be big news if someone could show it is GapP-complete. Mar 13 comment Littlewood-Richardson rule for the complete flag variety: GapP complete? Isn't this question essentially asking about the status of a well-known open problem? Mar 12 comment regular triangulations of the product of two simplices They should be the same as combinatorial types of tropical hyperplane arrangements. See arxiv.org/pdf/math/0605598.pdf Mar 7 awarded Nice Question Mar 7 comment Counting problems where unlabeled is easier than labeled @PerAlexandersson: Perhaps this somewhat trivial example was meant in jest but it actually does fit nicely into the hyperplane arrangement story. You can count unlabeled semiorders by counting regions of $\{x_i-x_j=1\colon 1\leq i,j \leq n\}$ that intersect $x_1 < x_2 < \cdots < x_n$ and you can count unlabeled threshold graphs by counting regions of $\{x_i+x_j = 0\colon 1 \leq i < j \leq n\}$ that intersect $|x_1| < |x_2| < \cdots < |x_n|$. Similarly you can count unlabeled stone arrangements by counting regions of $\{x_i-x_j = 0\}$ that intersect $x_1 < \cdots < x_n$. Mar 6 revised Counting problems where unlabeled is easier than labeled edited tags