JCT
2016
8 years 9 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
8 years 9 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
8 years 9 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
8 years 9 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
8 years 9 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
8 years 9 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
8 years 9 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
8 years 9 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
8 years 9 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
8 years 9 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...