David G. Wagner

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Abstmct We reveal an equivalence relation between the construction of a new class of low density MDS array codes, that we call B-Code, and a combinatorial problem known as perfect one-factorization of complete graphs. We use known perfect one-factors of complete graphs to create constructions and decoding algorithms for both B-Code and its dual code. B-Code(More)
For a finite multigraph G, the reliability function of G is the probability RG(q) that if each edge of G is deleted independently with probability q then the remaining edges of G induce a connected spanning subgraph of G; this is a polynomial function of q. In 1992, Brown and Colbourn conjectured that for any connected multigraph G, if q ∈ C is such that(More)
Motivated by a property of linear resistive electrical networks, we introduce the class of Rayleigh matroids. These form a subclass of the balanced matroids defined by Feder and Mihail [10] in 1992. We prove a variety of results relating Rayleigh matroids to other well–known classes – in particular, we show that a binary matroid is Rayleigh if and only if(More)
Let P be a nite partial order which does not contain an induced subposet isomorphic with 3 + 1, and let G be the incomparability graph of P . Gasharov has shown that the chromatic symmetric function XG has nonnegative coe cients when expanded in terms of Schur functions; his proof uses the dual Jacobi-Trudi identity and a sign-reversing involution to(More)
Univariate polynomials with only real roots, while special, do occur often enough that their properties can lead to interesting conclusions in diverse areas. Due mainly to the recent work of two young mathematicians, Julius Borcea and Petter Brändén, a very successful multivariate generalization of this method has been developed. The first part of this(More)
In 1981, Stanley applied the Aleksandrov–Fenchel Inequalities to prove a logarithmic concavity theorem for regular matroids. Using ideas from electrical network theory we prove a generalization of this for the wider class of matroids with the “half–plane property”. Then we explore a nest of inequalities for weighted basis– generating polynomials that are(More)