Chord conjecture for longest cycles containing a linear forest

From papers

Let GG be a kk-connected graph with k2k\geq 2, and let FF be a linear forest, meaning a graph whose components are paths, that is a subgraph of GG with ll edges and tt isolated vertices. Assume that

l+tk2.l+t\leq k-2.

A longest cycle passing through FF is a cycle containing FF with maximum length among all cycles of GG that contain FF. Wu--Zhang's conjecture. Every longest cycle of GG passing through FF has a chord.

The connectivity assumption ensures that a cycle containing FF exists. The paper proves the conjecture for several cases involving a linear forest with at most one edge and sufficiently large circumference, while the full statement remains open on the supplied evidence.

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Sources & referencesView supporting material

Primary source

Haidong Wu and Shunzhe Zhang, “Chords of longest cycles in graphs with large circumferences”, arXiv:2511.03422 (2025).

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