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arXiv · 0903.4405

Binary nullity, Euler circuits and interlace polynomials

Lorenzo Traldi
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Abstract

A theorem of Cohn and Lempel [J. Combin. Theory Ser. A 13 (1972), 83-89] gives an equality relating the number of circuits in a directed circuit partition of a 2-in, 2-out digraph to the GF(2)-nullity of an associated matrix. This equality is essentially equivalent to the relationship between directed circuit partitions of 2-in, 2-out digraphs and vertex-nullity interlace polynomials of interlace graphs. We present an extension of the Cohn-Lempel equality that describes arbitrary circuit partitions in (undirected) 4-regular graphs. The extended equality incorporates topological results that have been of use in knot theory, and it implies that if H is obtained from an interlace graph by attaching loops at some vertices then the vertex-nullity interlace polynomial $q_{N}(H)$ is essentially the generating function for certain circuit partitions of an associated 4-regular graph.

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Lorenzo Traldi. 2009-12-31. Binary nullity, Euler circuits and interlace polynomials. https://arxiv.org/abs/0903.4405

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