Stability conjecture for nontrivial direct product graph pairs

A graph pair (Γ,Σ)(\Gamma,\Sigma) is nontrivial if Γ\Gamma and Σ\Sigma are coprime connected twin-free graphs and exactly one of them is bipartite. A graph pair is stable if it has no unexpected automorphisms under the direct product construction. Stability conjecture. Let (Γ,Σ)(\Gamma,\Sigma) be a nontrivial graph pair with Σ\Sigma bipartite. Then (Γ,Σ)(\Gamma,\Sigma) is stable if and only if Γ\Gamma is stable.

The conjecture would eliminate the need for any additional condition in the reduction of stability for a nontrivial pair with bipartite second factor to stability of the single graph Γ\Gamma. Explicitly determining stable nontrivial pairs is difficult, even when Σ=K2\Sigma=K_2, so the conjecture represents a broad proposed reduction of the stability problem.

Sources & referencesView supporting material

Primary source

Xiaomeng Wang, Yan-Li Qin and Binzhou Xia, “The existence of unexpected automorphisms in direct product graphs”, arXiv:2509.26170 (2026).

Additional references

2 papers in this index state this conjecture (2022–2025). The statement above is taken from the most recent of them; the others are arXiv:2210.06777.

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