C4-free graphs of bounded degree
نویسنده
چکیده
Answering some questions of Gutman, we show that, except for four specific trees, every connected graph G of order n, with no cycle of order 4 and with maximum degree at most 3, satisfies |μ1|+ · · ·+ |μn| ≥ n, where μ1, . . . , μn are the eigenvalues of G. We give some general results and state two conjectures. AMS classification: 05C50
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