Channels, Billiards, and Perfect Matching 2-Divisibility

نویسندگان

چکیده

Let $m_G$ denote the number of perfect matchings graph $G$. We introduce a combinatorial tools for determining parity and giving lower bound on power 2 dividing $m_G$. In particular, we certain vertex sets called channels, which correspond to elements in kernel adjacency matrix $G$ modulo $2$. A result Lov\'asz states that existence nontrivial channel is equivalent being even. give new proof this strengthen it by showing channels gives $2$ when planar. describe local operations preserve channels. also establish surprising connection between 2-divisibility dynamical systems an equivalency billiard paths. exploit relationship show $2^{\frac{\gcd(m+1,n+1)-1}{2}}$ divides domino tilings $m\times n$ rectangle. use paths fast algorithm counting (and hence tilings) simply connected regions square grid.

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ژورنال

عنوان ژورنال: Electronic Journal of Combinatorics

سال: 2021

ISSN: ['1077-8926', '1097-1440']

DOI: https://doi.org/10.37236/9151