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Discrete MathematicsΒ· 2026Q1

Minimum forcing numbers of perfect matchings of circular and prismatic graphs

Qiaoyun Shi, Heping Zhang

Short summary

This paper establishes that for a bipartite graph G on n vertices with an involutory weighted adjacency matrix over a field of characteristic not 2, the minimum size of a matching uniquely extendable to a perfect matching in G β–‘ Cβ‚‚k is n, for all k β‰₯ 2.

AI-generated from the title and abstract; the full text is not read.

Key points

  • Introduces the concept of the minimum forcing number f(G) for a graph G with a perfect matching.
  • Extends previous results on f(Qd) and f(G β–‘ Kβ‚‚) to G β–‘ Cβ‚‚k.
  • Proves that for a bipartite graph G on n vertices with an involutory weighted adjacency matrix (characteristic β‰  2), f(G β–‘ Cβ‚‚k) = n for k β‰₯ 2.
  • Shows the method applies to some unbalanced bipartite graphs with specific weighted bi-adjacency matrices.

AI-generated from the title and abstract; the full text is not read.

Abstract

Let G be a graph with a perfect matching. Denote by 𝑓 ⁑ ( 𝐺 ) the minimum size of a matching in G that is uniquely extendable to a perfect matching in G . Diwan (2019) used linear algebra to prove that for the d -hypercube 𝑄 𝑑 ( 𝑑 β‰₯ 2 ) , 𝑓 ⁑ ( 𝑄 𝑑 ) = 2 𝑑 βˆ’ 2 , thus settling a conjecture of Pachter and Kim (1998). Recently, Mohammadian generalized this method to prove a general result: for a bipartite graph G on n vertices, if G admits an involutory weighted adjacency matrix A over a field F , then 𝑓 ⁑ ( 𝐺 β–‘ 𝐾 2 ) = 𝑛 2 , where β–‘ denotes the Cartesian product of two graphs. In this paper we obtain 𝑓 ⁑ ( 𝐺 β–‘ 𝐢 2 ⁒ π‘˜ ) = 𝑛 when a bipartite graph G on n vertices admits an involutory weighted adjacency matrix A over a field F of characteristic not 2, for all integers π‘˜ β‰₯ 2 . Moreover, we demonstrate that this method can also be applied to some unbalanced bipartite graphs G when G admits a weighted bi-adjacency matrix with orthogonal rows.

The authors' abstract, as published at the source. Discrete Mathematics, 2026 Β· DOI β†—

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Field: Geometry and Topology

Geometry and TopologyMathematics