Linearly compact rings having a simple group of units

Those linearly compact rings with identity having a simple group of units and a transfinitely nilpotent Jacobson radical are identified. A consequence of this characterization is Cohen and Koh's classification theorem for compact rings with identity having a simple group of units.     

椭圆方程的变换群与变分恒等式

讨论了椭圆方程的变换群与变分恒等式的关系,利用变分对称群的性质得到一类变分恒等式.通过计算变分对称群得到了寻找非星形区域方法并举例进行了说明.     

Approximate Identities for Ideals of Segal Algebras on A Compact Group

We show that every closed ideal of a Segal algebra on a compact group admits a central approximate identity which has the property, called condition (U), that the induced multiplication operators converge to the identity operator uniformly on compact sets of the ideal. This result extends a known one due to H. Reiter who has considered the problem under the condition that the Segal algebra is symmetric. We prove further that a closed right ideal of a Segal algebra on a compact group admits a left approximate identity satisfying condition (U) if and only if it is approximately complemented as a subspace of the Segal algebra; if in addition the Segal algebra is symmetric, then a closed left ideal admits a right approximate identity satisfying condition (U) if and only if it is approximately complemented.     

Group identities on units of locally finite algebras and twisted group algebras

We study locally finite algebras and twisted group algebras with units satisfying a group identity. As a preliminary result, we obtain a necessary condition for twisted group algebras to satisfy a generalized polynomial identity.     

Group algebras whose units satisfy a Laurent polynomial identity

Let KG be the group algebra of a torsion group G over a field K. We show that if the units of KG satisfy a Laurent polynomial identity, which is not satisfied by the units of the relative free algebra \(K[\alpha ,\beta : \alpha ^2=\beta ^2=0]\), then KG satisfies a polynomial identity. This extends Hartley’s Conjecture which states that if the units of KG satisfy a group identity, then KG satisfies a polynomial identity. As an application we prove that if the units of KG satisfy a Laurent polynomial identity whose support has cardinality at most 3, then KG satisfies a polynomial identity.     

Uniqueness of Polish group topology

We show the limits of Mackey's theorem applied to identity sets to prove that a given group has a unique Polish group topology.Verbal sets in Abelian Polish groups and full verbal sets in the infinite symmetric group are Borel. However this is not true in general.A Polish group with a neighborhood π-base at 1 of sets from the σ-algebra of identity and verbal sets has a unique Polish group topology. It follows that compact, connected, simple Lie groups, as well as finitely generated profinite groups, have a unique Polish group topology.     

Picone’s identity for biharmonic operators on Heisenberg group and its applications

In this paper, we establish a nonlinear analogue of Picone’s identity for biharmonic operators on Heisenberg group. As an applications of Picone’s identity, we obtain Hardy-Rellich type inequality, Morse index, Caccioppoli inequality, Picone inequality for biharmonic operators on Heisenberg group.     

Commutators of contactomorphisms

The group of volume preserving diffeomorphisms, the group of symplectomorphisms and the group of contactomorphisms constitute the classical groups of diffeomorphisms. The first homology groups of the compactly supported identity components of the first two groups have been computed by Thurston and Banyaga, respectively. In this paper we solve the long standing problem on the algebraic structure of the third classical diffeomorphism group, i.e. the contactomorphism group. Namely we show that the compactly supported identity component of the group of contactomorphisms is perfect and simple (if the underlying manifold is connected). The result could be applied in various ways.     

Jacobi identity for groups

In group calculations connected with multiple commutators, it may become necessary to reduce all the commutators to the left-normalized form (with respect to the arrangement of parentheses). To this end, an identity representing a natural extension of the Jacobi identity in Lie algebras is given. The identity is proved up to elements of the tenth term of the central filtration.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 46, pp. 53–58, 1974.     

Symmetric units and group identities

In this paper we study rings R with an involution whose symmetric units satisfy a group identity. An important example is given by FG, the group algebra of a group G over a field F; in fact FG has a natural involution induced by setting g?g ⁻¹ for all group elements g∈G. In case of group algebras if F is infinite, charF≠ 2 and G is a torsion group we give a characterization by proving the following: the symmetric units satisfy a group identity if and only if either the group of units satisfies a group identity (and a characterization is known in this case) or char F=p >0 and 1) FG satisfies a polynomial identity, 2) the p-elements of G form a (normal) subgroup P of G and G/P is a Hamiltonian 2-group; 3) G is of bounded exponent 4p ^s for some s≥ 0. Received: 8 August 1997     

The equation x 2 y 2 = g in partially commutative groups

A partially commutative group is a group defined by generators and relations so that all defining relations are of the form: the commutator of two generators is equal to the identity element. We consider an algorithm for checking whether a given group element is a product of two squares. This generalizes a result of Wicks for free groups.     

Some Skew Linear Groups Satisfying Generalized Group Identities

In this article, we consider a type of generalized group identity and extend some earlier results. For example, we show that, if D is a division ring with infinite center, then every subnormal subgroup of GL_n(D) satisfying a generalized group identity over GL_n(D) is central.     

Every finite semigroup is embeddable in a finite relatively free semigroup

The title result is proved by a Murskii-type embedding.Results on some related questions are also obtained. For instance, it is shown that every finitely generated semigroup satisfying an identity ξ^d=ξ^2d is embeddable in a relatively free semigroup satisfying such an identity, generally with a larger d; but that an uncountable semigroup may satisfy such an identity without being embeddable in any relatively free semigroup.It follows from known results that every finite group is embeddable in a finite relatively free group. It is deduced from this and the proof of the title result that a finite monoid S is embeddable by a monoid homomorphism in a finite (or arbitrary) relatively free monoid if and only if its group of invertible elements is either {e} or all of S.     

新型组合恒等式（一）

新型组合恒等式是研讨别开生面的几类组合孪生恒等式组的问题．本要主要研讨互逆类的组合孪生恒等式组，该类可分为多项式型、二项式定理型、指数函数型以及三角函数（或双曲函数）型等四型，一批成双出现的新结果。与许多著名数列（Ｆｉｂｏｎａｃｃｉ数列、Ｂｅｒｎｏｕｌｌｉ数、Ｅｕｌｅｒ数以及二项式定理系数数列等）有着密切关系．此外，本人还研讨了一类特殊行列式的性质及其应用。     

Connected components of compact matrix quantum groups and finiteness conditions

We introduce the notion of identity component of a compact quantum group and that of total disconnectedness. As a drawback of the generalized Burnside problem, we note that totally disconnected compact matrix quantum groups may fail to be profinite. We consider the problem of constructing the identity component by introducing canonical approximating transfinite sequences of subgroups. These sequences have lengths ≤1 in the classical case but can be countably infinite for duals of discrete groups. We give examples of free product quantum groups where the identity component is not normal and the associated sequence has length 1.     

On perfect graded rings

We prove that a group graded ring with finite support is right perfect if and only if the identity graded component is right perfect.     

Locally continuously perfect groups of homeomorphisms

The notion of a locally continuously perfect group is introduced and studied. This notion generalizes locally smoothly perfect groups introduced by Haller and Teichmann. Next, we prove that the path connected identity component of the group of all homeomorphisms of a manifold is locally continuously perfect. The case of equivariant homeomorphism group and other examples are also considered.     

Each Invertible Sharply d-Transitive Finite Permutation Set with d ≥ 4 is a Group

All known finite sharply 4-transitive permutation sets containing the identity are groups, namely S ₄, S ₅, A ₆ and the Mathieu group of degree 11. We prove that a sharply 4-transitive permutation set on 11 elements containing the identity must necessarily be the Mathieu group of degree 11. The proof uses direct counting arguments. It is based on a combinatorial property of the involutions in the Mathieu group of degree 11 (which is established here) and on the uniqueness of the Minkowski planes of order 9 (which had been established before): the validity of both facts relies on computer calculations. A permutation set is said to be invertible if it contains the identity and if whenever it contains a permutation it also contains its inverse. In the geometric structure arising from an invertible permutation set at least one block-symmetry is an automorphism. The above result has the following consequences. i) A sharply 5-transitive permutation set on 12 elements containing the identity is necessarily the Mathieu group of degree 12. ii) There exists no sharply 6-transitive permutation set on 13 elements. For d 6 there exists no invertible sharply d-transitive permutation set on a finite set with at least d + 3 elements. iii) A finite invertible sharply d-transitive permutation set with d 4 is necessarily a group, that is either a symmetric group, an alternating group, the Mathieu group of degree 11 or the Mathieu group of degree 12.     

关于正、余弦函数的一组恒等式

:利用第二类契贝谢夫多项式的性质得到了关于正余弦函数的一组有趣的恒等式 .     

Conformal mappings and CR mappings on the Engel group

We show that conformal mappings between the Engel groups are CR or anti-CR mappings. This reduces the determination of conformal mappings to a problem in the theory of several complex analysis. The result about the group of CR automorphisms is used to determine the identity component of the group of conformal mappings on the Engel group.