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Paired Domination in Cubic Bipartite Graphs
Abstract
A paired dominating set of a graph G is a dominating set D such that G[D] has a perfect matching. The minimum size of such a set is the paired domination number gpr(G). Desormeaux and Henning conjectured that every cubic bipartite graph G of order n satisfies gpr(G)≤ n/2. We prove the conjecture in the sharp integer form gpr(G)≤ 2⌊ |V(G)|/4⌋ for every finite simple cubic bipartite graph G. The proof combines a directed contraction along a perfect matching, switching arguments based on dominator trees, a four-symbol boundary calculus for two-edge cuts, and the Gallai--Edmonds decomposition. Equality is attained by K3,3 when |V(G)|≡2pmod4 and by the cube Q3 when |V(G)|≡0pmod4.
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BibTeX
@misc{lu2026paired,
title = {{Paired Domination in Cubic Bipartite Graphs}},
author = {Changhong Lu and Qi Wu},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.30152},
eprint = {2609.30152},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.30152},
}
RIS
TY - UNPB
TI - Paired Domination in Cubic Bipartite Graphs
AU - Changhong Lu
AU - Qi Wu
PY - 2026
DA - 2026/09/24
PB - arXiv
DO - 10.48550/arxiv.2609.30152
UR - https://arxiv.org/abs/2609.30152
AB - A paired dominating set of a graph G is a dominating set D such that G[D] has a perfect matching. The minimum size of such a set is the paired domination number gpr(G). Desormeaux and Henning conjectured that every cubic bipartite graph G of order n satisfies gpr(G)≤ n/2. We prove the conjecture in the sharp integer form gpr(G)≤ 2⌊ |V(G)|/4⌋ for every finite simple cubic bipartite graph G. The proof combines a directed contraction along a perfect matching, switching arguments based on dominator trees, a four-symbol boundary calculus for two-edge cuts, and the Gallai--Edmonds decomposition. Equality is attained by K_3,3 when |V(G)|≡2pmod4 and by the cube Q_3 when |V(G)|≡0pmod4.
ER -