A group H is said to be autocapable if there exists a group M such that H is isomorphic to the absolute central factor group M/L(M)of M.In this paper,we first prove that if N is a characteristic subgroup of an autocap...A group H is said to be autocapable if there exists a group M such that H is isomorphic to the absolute central factor group M/L(M)of M.In this paper,we first prove that if N is a characteristic subgroup of an autocapable group H,then N is neither the generalized quaternion group nor the semi-dihedral group.Next,we give the classification of finite groups G if G/L(G)is a 2-group of maximal class.展开更多
Let F be a number field and p be a prime. In the successive approximation theorem, we prove that, for each integer n ≥ 1, finitely many candidates for the Galois group of the nth stage of the p-class tower over F are...Let F be a number field and p be a prime. In the successive approximation theorem, we prove that, for each integer n ≥ 1, finitely many candidates for the Galois group of the nth stage of the p-class tower over F are determined by abelian type invariants of p-class groups C1pE of unramified extensions E/F with degree [E : F] = pn-1. Illustrated by the most extensive numerical results available currently, the transfer kernels (TE, F) of the p-class extensions TE, F : C1pF → C1pE from F to unramified cyclic degree-p extensions E/F are shown to be capable of narrowing down the number of contestants significantly. By determining the isomorphism type of the maximal subgroups S G of all 3-groups G with coclass cc(G) = 1, and establishing a general theorem on the connection between the p-class towers of a number field F and of an unramified abelian p-extension E/F, we are able to provide a theoretical proof of the realization of certain 3-groups S with maximal class by 3-tower groups of dihedral fields E with degree 6, which could not be realized up to now.展开更多
基金National Natural Science Foundation of China(12171302,11801334)Natural Science Foundation of Shanxi Province(202103021224287)+1 种基金Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi(2021L278)Science&Technology Development Fund of Tianjin Education Commission for Higher Education(2019KJ141).
文摘A group H is said to be autocapable if there exists a group M such that H is isomorphic to the absolute central factor group M/L(M)of M.In this paper,we first prove that if N is a characteristic subgroup of an autocapable group H,then N is neither the generalized quaternion group nor the semi-dihedral group.Next,we give the classification of finite groups G if G/L(G)is a 2-group of maximal class.
文摘Let F be a number field and p be a prime. In the successive approximation theorem, we prove that, for each integer n ≥ 1, finitely many candidates for the Galois group of the nth stage of the p-class tower over F are determined by abelian type invariants of p-class groups C1pE of unramified extensions E/F with degree [E : F] = pn-1. Illustrated by the most extensive numerical results available currently, the transfer kernels (TE, F) of the p-class extensions TE, F : C1pF → C1pE from F to unramified cyclic degree-p extensions E/F are shown to be capable of narrowing down the number of contestants significantly. By determining the isomorphism type of the maximal subgroups S G of all 3-groups G with coclass cc(G) = 1, and establishing a general theorem on the connection between the p-class towers of a number field F and of an unramified abelian p-extension E/F, we are able to provide a theoretical proof of the realization of certain 3-groups S with maximal class by 3-tower groups of dihedral fields E with degree 6, which could not be realized up to now.
