Sharp uppper and lower bounds on the number of spanning trees in Cartesian product graphs
Author(s) -
Jernej Azarija
Publication year - 2013
Publication title -
discussiones mathematicae graph theory
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.476
H-Index - 19
eISSN - 2083-5892
pISSN - 1234-3099
DOI - 10.7151/dmgt.1698
Subject(s) - cartesian product , mathematics , combinatorics , spanning tree , product (mathematics) , upper and lower bounds , cartesian coordinate system , simple (philosophy) , discrete mathematics , geometry , mathematical analysis , philosophy , epistemology
Let G1 and G2 be simple graphs and let n1 = |V (G1)|, m1 = |E(G1)|, n2 = |V (G2)| and m2 = |E(G2)|. In this paper we derive sharp upper and lower bounds for the number of spanning trees τ in the Cartesian product G1 □G2 of G1 and G2. We show that: and . We also characterize the graphs for which equality holds. As a by-product we derive a formula for the number of spanning trees in Kn1 □Kn2 which turns out to be .
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