Belkhechine–Bouaziz–Boudabbous–Pouzet conjecture for path-reversed tournaments

From papers

Let QnQ_n be the tournament on [n]={1,,n}[n]=\{1,\ldots,n\} obtained from the natural transitive tournament by reversing precisely the consecutive pairs 12,23,,(n1)n12,23,\ldots,(n-1)n. Equivalently, for i<ji<j, orient iji\to j when ji+2j\geq i+2, and orient i+1ii+1\to i when j=i+1j=i+1. Here inv(D)\operatorname{inv}(D) denotes the minimum size of a family of vertex-set inversions whose application produces an acyclic, equivalently transitive, tournament. Belkhechine–Bouaziz–Boudabbous–Pouzet conjecture. The inversion number of QnQ_n is

inv(Qn)=n12.\operatorname{inv}(Q_n)=\left\lfloor\frac{n-1}{2}\right\rfloor.

This conjecture concerns the exact number of induced subtournament reversals needed to make the structured tournament QnQ_n transitive. The supplied source does not state its resolution; the status is therefore left open.

Progress summary

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Sources & referencesView supporting material

Primary source

Yaping Mao, “The inversion number of a path-reversed tournament: Resolving a conjecture of Belkhechine, Bouaziz, Boudabbous, and Pouzet”, arXiv:2607.13829 (2026).

Additional references

2 papers in this index state this conjecture (2022–2026). The statement above is taken from the most recent of them; the others are arXiv:2212.11969.

Solutions 0

No solutions have been posted yet.