The Pairing-Hamiltonian property in Cartesian products of graphs
Abstract
Let G be a simple graph of even order at least four, and let KG denote the complete graph on V(G). A perfect matching of KG is called a pairing of G. The graph G has the Pairing-Hamiltonian property, or PH-property, if every pairing M of G admits a perfect matching N⊆ E(G), disjoint from M, such that M∪ N is a Hamiltonian cycle of KG. We prove that the PH-property is preserved under Cartesian products. More precisely, for graphs G and H of even order at least four, we show that both G and H are PH if and only if every pairing of G□ H admits a Hamiltonian completion contained in a spanning union of vertex-disjoint prisms determined by a perfect matching of G or of H. Without this support restriction, the converse fails: a Cartesian product may be PH even when neither of the two graphs is PH.
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BibTeX
@misc{romaniello2026pairinghamiltonian,
title = {{The Pairing-Hamiltonian property in Cartesian products of graphs}},
author = {Federico Romaniello},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.21682},
eprint = {2609.21682},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.21682},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - The Pairing-Hamiltonian property in Cartesian products of graphs
AU - Federico Romaniello
PY - 2026
DA - 2026/09/18
PB - arXiv
DO - 10.48550/arxiv.2609.21682
UR - https://arxiv.org/abs/2609.21682
AB - Let G be a simple graph of even order at least four, and let K_G denote the complete graph on V(G). A perfect matching of K_G is called a pairing of G. The graph G has the Pairing-Hamiltonian property, or PH-property, if every pairing M of G admits a perfect matching N⊆ E(G), disjoint from M, such that M∪ N is a Hamiltonian cycle of K_G. We prove that the PH-property is preserved under Cartesian products. More precisely, for graphs G and H of even order at least four, we show that both G and H are PH if and only if every pairing of G□ H admits a Hamiltonian completion contained in a spanning union of vertex-disjoint prisms determined by a perfect matching of G or of H. Without this support restriction, the converse fails: a Cartesian product may be PH even when neither of the two graphs is PH.
ER -