Automorphism-group conjecture for wreath-product designs

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Let D~\widetilde{\mathscr{D}} be the input design, let ee and k~\widetilde{k} be the parameters of Construction D(D~,e)\mathscr{D}(\widetilde{\mathscr{D}},e), and let Aut⁡\operatorname{Aut} denote the automorphism group. Automorphism-group conjecture. If e≥3e\geq 3 or k~≥3\widetilde{k}\geq 3, then

Aut⁡(D(D~,e))=Aut⁡(D~)≀Se.\operatorname{Aut}(\mathscr{D}(\widetilde{\mathscr{D}},e))=\operatorname{Aut}(\widetilde{\mathscr{D}})\wr S_e.

Computations suggest that the displayed equality holds in most small examples, with the exceptional cases described in the surrounding discussion; the conjecture concerns whether those exceptions are the only ones.

References

Primary source

Carmen Amarra, Alice Devillers and Cheryl E. Praeger, “Recursive constructions for block-transitive, poset-imprimitive two-designs”, arXiv:2607.03029 (2026).

Additional references

11 papers in this index state this conjecture (2015–2026). The statement above is taken from the most recent of them; the others are arXiv:2603.07707, arXiv:2602.15264, arXiv:2504.05721, arXiv:2408.06283, arXiv:2407.19745, arXiv:2306.10744, arXiv:1907.06008, arXiv:1810.12855, arXiv:1704.08474, arXiv:1508.07279.

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