Salia's cycle-cover conjecture for infinite bipartite graphs

From papers

Let GG be a bipartite graph with sides AA and BB. For a subset XV(G)X\subseteq V(G) with X2|X|\geq 2, let NG2(X)N^2_G(X) be the set of vertices having at least two neighbors in XX. The graph GG has the double Hall property if NG2(X)X|N^2_G(X)|\geq |X| for every XAX\subseteq A with X2|X|\geq 2.

Salia's conjecture. If GG has the double Hall property, then for every XAX\subseteq A with X2|X|\geq 2 there is a cycle CXC_X in GG such that

V(CX)A=X.V(C_X)\cap A=X.

The conjecture proposes that the double Hall condition is sufficient to find a cycle covering any prescribed finite or infinite subset of AA of size at least two, with no other vertices of AA on the cycle. The supplied text gives no resolution, so the conjecture is recorded as open.

Progress summary

Nothing recorded yet. Refresh searches the literature and the public web for attempts on this problem, and writes the first summary here.

Sources & referencesView supporting material

Primary source

Leandro Aurichi, Paulo Magalhães Júnior and Lyubomyr Zdomskyy, “On cycle covers of infinite bipartite graphs”, arXiv:2504.02816 (2025).

Additional references

2 papers in this index state this conjecture (2025). The statement above is taken from the most recent of them; the others are arXiv:2502.10903.

Solutions 0

No solutions have been posted yet.