104
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JCT
2016
10 years 27 days 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 ...
111
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JCT
2016
10 years 27 days 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 ...
115
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JCT
2016
10 years 27 days 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...
104
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JCT
2016
10 years 27 days 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
10 years 27 days 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...