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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