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Vol 232, No 5 (2018)

Article

Local-Global Principle for the General Quadratic and General Hermitian Groups and the Nilpotency of KH1

Basu R.

Abstract

In this article, an analog of the Quillen–Suslin’s local-global principle was established for the elementary subgroup of the general quadratic group and the general Hermitian group. It is shown that unstable K1-groups of the general Hermitian groups over module finite rings are nilpotent-by-Abelian. This generalizes earlier results by A. Bak, R. Hazrat, and N. Vavilov.

Journal of Mathematical Sciences. 2018;232(5):591-609
pages 591-609 views

Normalizers of Elementary Overgroups of Ep(2, A)

Voronetsky E.Y.

Abstract

Let A be an involution ring, e1 , . . . , en be a full system of Hermitian idempotents in A, let every ei generate A as a two-sided ideal, and 2 ∈ A. In this paper, the normalizers of the groups Ep(2,A) · E(2,A, I) are calculated under natural assumptions on A, where Ep(2,A) denotes the elementary symplectic group, E(2,A, I) stands for the elementary subgroup of level I.

Journal of Mathematical Sciences. 2018;232(5):610-621
pages 610-621 views

Hochschild Cohomology for Algebras of Semidihedral Type. VII. Algebras with a Small Parameter

Generalov A.I.

Abstract

The Hochschild cohomology groups are computed for algebras of semidihedral type, which are contained in the family SD(2ℬ)2(k, t, c) (from the famous K. Erdmann’s classification) in the case where k = 1. In the calculation, the beforehand construction of the minimal bimodule resolution for algebras from the subfamily under discussion is used.

Journal of Mathematical Sciences. 2018;232(5):622-634
pages 622-634 views

On Derived Equivalence of Algebras of Semidihedral Type with Two Simple Modules

Generalov A.I., Zaikovskii A.A.

Abstract

The Hochschild cohomology groups of degrees not exceeding 3 are computed for algebras of semidihedral type that form the family SD(2B)1 (from the famous K. Erdmann’s classification). In the calculation, the beforehand construction of the initial part of the minimal projective bimodule resolution is used for algebras from the family under discussion. The obtained results imply that the algebras from the families SD(2B)1 and SD(2B)2 with the same parameters in defining relations are not derived equivalent.

Journal of Mathematical Sciences. 2018;232(5):635-646
pages 635-646 views

Double Cosets of Stabilizers of Totally Isotropic Subspaces in a Special Unitary Group. I

Gordeev N., Rehmann U.

Abstract

Let D be a division algebra with a fixed involution, and let V be the corresponding unitary space over D with T -condition (see N. Bourbaki, Algèbre). For a pair of totally isotropic subspaces u, v ≤ V, the double cosets PuγPv of their stabilizers Pu, Pv in Γ = SU(V ) are considered. A description of the cosets PuγPv in terms of the intersection distance din(u, γ(v)) and the Witt index of u + γ(v) is given.

Journal of Mathematical Sciences. 2018;232(5):647-661
pages 647-661 views

On the Ultrasolvability of p-Extensions of an Abelian Group by a Cyclic Kernel

Kiselev D.D.

Abstract

The paper contains a solution of A. V. Yakovlev’s problem in the embedding theory for p-extensions of odd order with a cyclic normal subgroup and an Abelian quotient group: for such nonsplit extensions there exists a realization for the quotient group as a Galois group over number fields such that the corresponding embedding problem is ultrasolvable (i.e., this embedding problem is solvable and has only fields as solutions). A solution for embedding problems of p-extensions of odd order with kernel of order p and with a quotient group that is represented by a direct product of its proper subgroups is also given – this is a generalization for p > 2 of an analogous result for p = 2 due to A. Ledet.

Journal of Mathematical Sciences. 2018;232(5):662-676
pages 662-676 views

On the Ultrasolvability of Some Classes of Minimal Nonsplit p-Extensions with Cyclic Kernel for p > 2

Kiselev D.D., Chubarov I.A.

Abstract

For any nonsplit p > 2-extension of finite groups with a cyclic kernel and a quotient group with two generators all the accompanying extensions of which split, there exists a realization of the quotient group as a Galois group of number fields such that the corresponding embedding problem is ultrasolvable (i.e., this embedding problem is solvable and has only fields as solutions).

Journal of Mathematical Sciences. 2018;232(5):677-692
pages 677-692 views

Serial Group Rings of Classical Groups Defined Over Fields with an Odd Number of Elements

Kukharev A.V., Puninski G.E.

Abstract

Simple finite classical groups defined over fields of odd characteristic the group rings of which over a given field are serial are enumerated.

Journal of Mathematical Sciences. 2018;232(5):693-703
pages 693-703 views

Formal Modules for Relative Formal Lubin–Tate Groups

Madunts A.I.

Abstract

Relative formal Lubin–Tate groups are studied, namely, their structure, the ring of endomorphisms, and the group of points. The primary elements are considered, and an explicit formula for the generalized Hilbert symbol is derived.

Journal of Mathematical Sciences. 2018;232(5):704-716
pages 704-716 views

On the Normalizer of a Unipotent Root Subgroup in a Chevalley Group

Nesterov V.V.

Abstract

In the present paper, the normalizer of a unipotent short and long root subgroup in a Chevalley group over an arbitrary field is calculated in detail. Surely this result is known to specialists. However the author could not find a reference to it.

Journal of Mathematical Sciences. 2018;232(5):717-720
pages 717-720 views

Vector Bundles on P1 with Simple Jumps

Smirnov A.L.

Abstract

Vector bundles of rank 2 on the projective line over ℤ are considered. It is assumed that such a bundle E is trivial on a generic fiber, and its restriction to any special fiber is isomorphic either to O2 or to O(−1)⊕O(1). Under these assumptions it is proved that an exact sequence of the form 0→O(−2) → E →O(2) → 0 exists.

Journal of Mathematical Sciences. 2018;232(5):721-731
pages 721-731 views

Vector Bundles on P1 with Generic Fiber OO(1) and Simple Jumps

Iakovenko S.S.

Abstract

Vector bundles on the projective line over a Dedekind domain A are studied. In the case where A is a principal ideal domain, a complete classification is obtained for rank 2 vector bundles with generic fiber O ⊕ O(1) and special fibers isomorphic either to O ⊕ O(1) or to O(−1) ⊕ O(2).

Journal of Mathematical Sciences. 2018;232(5):732-745
pages 732-745 views