数学季刊 ›› 2023, Vol. 38 ›› Issue (4): 349-359.doi: 10.13371/j.cnki.chin.q.j.m.2023.04.002
摘要: Let G be a finite simple graph and A(G) be its adjacency matrix. Then
G is singular if A(G) is singular. The graph obtained by bonding the starting vertices and ending vertices of three paths Pa1, Pa2 , Pa3 is called θ-graph, represented
by θ(a1,a2,a3). The graph obtained by bonding the two end vertices of the path
Ps to the vertices of the θ(a1,a2,a3) and θ(b1,b2,b3) of degree three, respectively,
is denoted by α(a1,a2,a3,s,b1,b2,b3) and called α-graph. β-graph is denoted when
β(a1,a2,a3,b1,b2,b3) =α(a1,a2,a3,1,b1,b2,b3). In this paper, we give the necessary and
sufficient conditions for the singularity of α-graph and β-graph, and prove that the
probability that a random given α-graph and β-graph is a singular graph is equal to 1423/2048
and 733/1024 , respectively.
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