数学季刊 ›› 2017, Vol. 32 ›› Issue (3): 238-245.doi: 10.13371/j.cnki.chin.q.j.m.2017.03.002
摘要: A k-cyclic graph is a connected graph of order n and size n + k-1. In this paper, we determine the maximal signless Laplacian spectral radius and the corresponding extremal graph among all C4-free k-cyclic graphs of order n. Furthermore, we determine the first three unicycles and bicyclic, C4-free graphs whose spectral radius of the signless Laplacian is maximal. Similar results are obtained for the(combinatorial) Laplacian
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