IMI Interdisciplinary Mathematics InstituteCollege of Arts and Sciences

## CANCELLED: A Generalization of the Harary-Sachs Theorem to Hypergraphs

• Sept. 14, 2018
• 2:30 p.m.
• LeConte 317R

## Abstract

This seminar was cancelled due to Hurricane Florence

We give a complete description of the coefficients of the characteristic polynomial $\chi _ H(\lambda)$ of a ($k$-uniform) hypergraph $H$, defined by the hyperdeterminant $\det(\mathcal{A} - \lambda \mathcal{I})$, where $\mathcal{A}$ is of the adjacency tensor/hypermatrix of $H$, and the hyperdeterminant is defined in terms of resultants of homogeneous systems associated to its argument. The co-degree $k$ coefficients can be obtained by an explicit formula yielding a linear combination of subgraph counts in $H$ of certain "Veblen hypergraphs''. This generalizes the Harary-Sachs Theorem for graphs, provides hints of a Leibniz-type formula for symmetric hyperdeterminants, and can be used in concert with computational algebraic methods to obtain the full characteristic polynomial of many new hypergraphs, even when the degrees of these polynomials is enormous. Joint work with Greg Clark of USC.

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