Volume 4 • Issue 1 • PP: 01–04 • 2024
The Basis Number of Connected Vertex-Disjoint Graphs
Open Access & Copyright
© 2024 The Author(s). Published by ASPG. This article is licensed under the Creative Commons Attribution 4.0 International License (CC BY 4.0).
Abstract
The basis number b(G) of a graph G is defined to be the smallest positive integer k such that G has a k-fold basis for its cycle space. We seek an upper bound for b(G1 +G2 +G3 +G4). We prove that if G1, G2, G3, and G4 are connected vertex-disjoint graphs and each has a spanning tree of vertex degree at most 4, then
b(G1 +G2 +G3 +G4) ≤ max{4,b(G1) + 1,b(G2) + 2,b(G3) + 2,b(G4) + 1}.
The basis number of the quadruple join of paths is also studied. In particular, we prove that
b(Pm +Pn +Pp +Pt ) = 4, m,t ≥ 5 and n, p ≥ 6.
Keywords
References
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