Abstract
It was conjectured by A. Bouchet that every bidirected graph which admits a nowhere-zero k-flow admits a nowhere-zero 6-flow. He proved that the conjecture is true when 6 is replaced by 216. O. Zyka improved the result with 6 replaced by 30. R. Xu and C. Q. Zhang showed that the conjecture is true for 6-edge-connected graph, which is further improved by A. Raspaud and X. Zhu for 4-edge-connected graphs. The main result of this paper improves Zyka’s theorem by showing the existence of a nowhere-zero 25-flow for all 3-edge-connected graphs.
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Wei, E., Tang, W. & Wang, X. Flows in 3-edge-connected bidirected graphs. Front. Math. China 6, 339–348 (2011). https://doi.org/10.1007/s11464-011-0111-3
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DOI: https://doi.org/10.1007/s11464-011-0111-3