Dai–Zhang–Broerama–Zhang conjecture on Hamiltonicity of connected K_{1,r}-free split graphs

From papers

Let rr be an integer with r3r\ge 3. A graph is K1,rK_{1,r}-free if it has no induced subgraph isomorphic to K1,rK_{1,r}, and a graph is Hamiltonian if it contains a cycle containing all its vertices. A graph is kk-connected if deleting fewer than kk vertices leaves it connected.

Dai–Zhang–Broerama–Zhang conjecture. Every (r1)(r-1)-connected K1,rK_{1,r}-free split graph is Hamiltonian.

The conjecture extends the known cases r=3r=3, where it follows from the characterization of Hamiltonian claw-free split graphs, and r=4r=4, established by Dai, Zhang, Broerama and Zhang. Its validity for general r3r\ge 3 is not resolved in the supplied source.

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Sources & referencesView supporting material

Primary source

Yiting Cai, Haiyan Guo, Hong-Jian Lai and Bo Zhou, “Tight spectral conditions for the Hamiltonicity of K_1,r-free split graphs”, arXiv:2604.14763 (2026).

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