半支配点 semiusemi_usemiu 的公式是这个吗？
semiu=min(dfnfau,min(v,u)∈E,dfnv>dfnulca(semiv,u))semi_u=\min(dfn_{fa_u},\min_{(v,u)\in E,dfn_v>dfn_u}lca(semi_v,u))semiu=min(dfnfau,min(v,u)∈E,dfnv>dfnulca(semiv,u))
