This paper considers such a group G which possesses nontrivial proper subgroups H 1 ,H 2 such that any proper subgroup of G not contained in H 1 ∪ H 2 is p-clo
Let S be a closed orientable surface of genus g ≥ 2,and C(S)the curve complex of S.In the paper,we introduce the concepts of 2-path between edges in C(S),which