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arXiv · 2605.28518

Counterexamples to Clique Immersion Conjecture for Direct Products

Chuanshu Wu·Zijian Deng
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Abstract

Let \(G\) and \(H\) be graphs, and let \(G\times H\) denote their direct product. For a graph \(G\), let \(\operatorname{im}(G)\) be the largest integer \(t\) such that \(G\) contains a \(K_t\)-immersion. Collins, Heenehan, and McDonald conjectured that if \(\operatorname{im}(G)=t\) and \(\operatorname{im}(H)=r\), then \[\operatorname{im}(G\times H)\ge (t-1)(r-1)+1.\] We disprove this conjecture by constructing an infinite family of connected bipartite counterexamples.

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Chuanshu Wu, Zijian Deng. 2026-05-28. Counterexamples to Clique Immersion Conjecture for Direct Products. https://arxiv.org/abs/2605.28518

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