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JCT

2016

4 years 5 months ago
2016

We study a toric degeneration of the Cox ring of the moduli of principal SLm(C) bundles on the projective line, with quasi parabolic data given by the the stabilizer of the highest...

JCT

2016

4 years 5 months ago
2016

A basic result in Ramsey theory states that any tournament contains a “large” transitive subgraph. Since transitive tournaments contain only transitive subgraphs, it is natura...

JCT

2016

4 years 5 months ago
2016

Let G and H be k-graphs (k-uniform hypergraphs); then a perfect H-packing in G is a collection of vertex-disjoint copies of H in G which together cover every vertex of G. For any ...

JCT

2016

4 years 5 months ago
2016

Given a ﬁnite point set P ⊂ Rd , a k-ary semi-algebraic relation E on P is the set of k-tuples of points in P, which is determined by a ﬁnite number of polynomial equations ...

JCT

2016

4 years 5 months ago
2016

There are numerous combinatorial objects associated to a Grassmannian permutation wλ that index cells of the totally nonnegative Grassmannian. We study some of these objects (rook...

JCT

2016

4 years 5 months ago
2016

A classic theorem in combinatorial design theory is Fisher’s inequality, which states that a family F of subsets of [n] with all pairwise intersections of size λ can have at mo...

JCT

2016

4 years 5 months ago
2016

We introduce a notion of bipartite minors and prove a bipartite analog of Wagner’s theorem: a bipartite graph is planar if and only if it does not contain K3,3 as a bipartite min...

JCT

2016

4 years 5 months ago
2016

The classical Littlewood-Richardson rule is a rule for computing coeﬃcients in many areas, and comes in many guises. In this paper we prove two Littlewood-Richardson rules for s...

JCT

2016

4 years 5 months ago
2016

Abstract. We consider a reﬁnement of the partition function of graph homomorphisms and present a quasi-polynomial algorithm to compute it in a certain domain. As a corollary, we ...

JCT

2016

4 years 5 months ago
2016

We deﬁne and study a recurrence relation in Z3 , called the hexahedron recurrence, which is similar to the octahedron recurrence (Hirota bilinear difference equation) and cube re...