It was conjectured by Bouchet that every bidirected graph which admits a nowhere-zero k flow will admit a nowhere-zero 6-flow.He proved that the conjecture is true when 6 is replaced by 216.Zyka improved the result with 6 replaced by 30.Xu and Zhang showed that the conjecture is true for 6-edge-connected graphs.And for 4-edge-connected graphs,Raspaud and Zhu proved it is true with 6 replaced by 4.In this paper,we show that Bouchet’s conjecture is true with 6 replaced by 15 for 3-edge-connected graphs.
机构:
INST MATH APPL GRENOBLE,STRUCT DISCRETES LAB,F-38402 ST MARTIN DHERES,FRANCEINST MATH APPL GRENOBLE,STRUCT DISCRETES LAB,F-38402 ST MARTIN DHERES,FRANCE