Stein's conjecture on oriented paths in graphs of large semidegree

Let GG be an oriented graph, let \b7\b7 denote its minimum semidegree, and let kk be a nonnegative integer. An orientation of the kk-edge path is an oriented graph obtained by assigning a direction to each edge of an undirected path with kk edges. Stein's conjecture. Every oriented graph GG with minimum semidegree \b7(G)>k/2\b7(G)>k/2 contains every orientation of the kk-edge path.

Jackson's theorem proves the directed-path case. Stein and Trujillo-Negrete proved the conjecture for oriented graphs containing no oriented 44-cycle, while the general statement remains open; the paper studies two-block paths as a step toward it.

Sources & referencesView supporting material

Primary source

Irena Penev, S Taruni, Stéphan Thomassé, Ana Trujillo-Negrete and Mykhaylo Tyomkyn, “Two-block paths in oriented graphs of large semidegree”, arXiv:2503.23191 (2026).

Additional references

2 papers in this index state this conjecture (2024–2025). The statement above is taken from the most recent of them; the others are arXiv:2406.03166.

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