A proof of the upper matching conjecture for large graphs

Autor: Will Perkins, Ewan Davies, Matthew Jenssen
Rok vydání: 2021
Předmět:
Zdroj: Journal of Combinatorial Theory, Series B. 151:393-416
ISSN: 0095-8956
DOI: 10.1016/j.jctb.2021.07.005
Popis: We prove that the ‘Upper Matching Conjecture’ of Friedland, Krop, and Markstrom and the analogous conjecture of Kahn for independent sets in regular graphs hold for all large enough graphs as a function of the degree. That is, for every d and every large enough n divisible by 2d, a union of n / ( 2 d ) copies of the complete d -regular bipartite graph maximizes the number of independent sets and matchings of size k for each k over all d-regular graphs on n vertices. To prove this we utilize the cluster expansion for the canonical ensemble of a statistical physics spin model, and we give some further applications of this method to maximizing and minimizing the number of independent sets and matchings of a given size in regular graphs of a given minimum girth.
Databáze: OpenAIRE