Pancyclicity conjecture for Bang–Jensen–Gutin–Li type conditions

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A digraph DD has order n≥3n\ge 3. A pair of nonadjacent vertices is dominated if it has a common in-neighbor, and dominating if it has a common out-neighbor. Let d(u)d(u) denote the total degree of a vertex uu, and let DL\mathcal{D}_L be the class of non-pancyclic locally semicomplete digraphs defined by the stated round-decomposition characterization. Let DB\mathcal{D}_B be the class of balanced complete bipartite digraphs with at least 44 vertices. Pancyclicity conjecture. If every vertex u∈V(D)u\in V(D) belonging to a nonadjacent dominated pair or a nonadjacent dominating pair satisfies d(u)≥nd(u)\ge n, then DD is pancyclic unless D∈DLD\in\mathcal{D}_L or D∈DBD\in\mathcal{D}_B. This conjecture seeks a pancyclicity criterion extending Bang–Jensen–Gutin–Li type Hamiltonicity conditions; the exceptional classes account for known non-pancyclic structures, while a complete characterization of non-pancyclic locally semicomplete digraphs under the relevant condition remains difficult.

References

Primary source

Zan-Bo Zhang, Wenhao Wu and Weihua He, “Cycles of lengths 3 and n-1 in digraphs under a Bang-Jensen-Gutin-Li type conditon”, arXiv:2504.21628 (2025).

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