Automorphisms of PGL_2(K) over Any Skew Field K

<正> Let K be a skew field and Z be its center.The multiplicative groups of non-zero ele-ments of K and Z are denoted by K~* and Z~* respectively.Denote by GL_2(K) the groupof all 2×2 matrices over K and by PGL_2(K) the factor group of GL_2(K) modulo its ce-nter consisting of all elements of the form γI,where γ∈Z~* and I is the 2×2 identitymatrix.If K is commutative or is of characteristic≠0 the automorphisms of PGL_2(K)are already determined.In the present paper,we'll determine the automorphisms of PGL_2(K)     

A New Type of Pronormal Subgroups in Chevalley Groups

Let L be a simple Lie algebra with irreducible root system φ having roots of different length,F be a field of characteristic different from 2,G=L(F) be a Chevalley group of type L over F.Denote by φ^1 the set of all long roots in φ.Set G^1=(zr(t);r∈φ^t,t∈F).It is a subgroup of G generated by all the long root subgroups.This paper determines the pronormality of G^1 in G when L is not of type G2.     

GL_2 OVER FULL RINGS

In this paper the authors generalize the result of B.R.McDonald.The following resultis obtained.Let R be a(1,6)-full ring,or(3,3)-full ring,or(2,4)-full ring,and R has theproperty T.G is an SL_2(R)-normal subgroup of GL_2(R).Then there is an ideal A in Rsuch thatSC(R,A)(?)G(?)GC(R,A).     

AN ANALOGUE OF KüNNETH THEOREM INSTRONG HOMOLOGY

1 IntroductiouLet G and Z be an abelian group and the set Of all integers respectively And letC = (C., ft,', I') denote an inverse system of chain complexes C. and chain maPS I..1: Cv, -Ct,7 5 T' indexed by a directed set r. Strong homology groups HP(C) of the inverse systemC were defilled by J. T. Lisica and S. Mardedie[n. Using the ANRresOlution[9'l1I, algebraictopolOgists defined the strong homology group HP(X; G) of a topological space X with coefficient8 in G and gave exMPl…     

ON ARC-TRANSITIVE CIRCULANT DIGRAPHS

Denote by c,(s)the circulant digraph with vertex set zn=[0,1,2……n-1]and symbol set s(≠-s)∈zn\[0].let x be the automorphism group of cn(S)and xo the stabilizer of o in x.then cn(S)is arctransitive if and only if xo acts transitively on s.in this paper,co(S)with xo is being the symmetric group is characterized by its symbot set .by the way all the arctransitive clcculant digraphs of degree 2are given.     

REVERSE ORDER LAW FOR GROUP INVERSE OF PRODUCT OF MATRICES ON SKEW FIELDS

Let K~(n×n) be the set of all n×n matrices and K_r~(n×n) the set {A∈K~(n×n)|rankA=r} on askew field K. Zhuang [1] denotes by A~# the group inverse of A∈K~(n×n) which is the solu-tion of the euqations:AXA=A, XAX=X, AX=AX.     

THE GENERALIZED SMASH PRODUCT AND COPRODUCT

91. PreliminariesThroughout the paper all spaces are over a fixed ground field K. If C is a coalgebra,then we always denote the comultiplication and counit by b and E respectively. Set b(c) Z of @ cd for c E C. If M is a right (left) C -comodule, then we use p for the structure mapof M, and set p(m) = ac(o) @ m(1) (p(m) ~ ac(--1) @ m(o)) for m E M. Let H be abialgebra. Denote left H-module category by HM and left H-comodule category by HM.If M and N are in HM, then M @ N is also a l…     

AN UNCERTAINTY PRINCIPLE ON THE GROUP OF RIGID MOTIONS OF THE PLANE

Let M(2)be the group of rigid motions of the plane.The Fourier transform and the Piancherel formulaon M(2)can be explicitly given by the general group representation theory.Using this fact.we establish akind of uncertainty principle on M(2).The result can easily be generalized to higher dimensional cases.Anapplication of the result yields an uncertainty principle on the Euclidean spaces obtained by R.S.Strichartz.     

On the Covering of the Vertices of a Graph by Cliques

In conversation I was told by Professor R.Brigham the following conjecture [1].Let G(n) be a graph of n vertices.Denote by f(G(n))=t the smallest integer for which the vertices of G(n) can be covered by t cliques. Denote further by h(G(n)) =l the largest integer for which there are l edges of our G(n) no two of Which are in the same clique.Clearly h(G(n)) can be much larger than f(G(n))e.g.if n=2m and G(n) is the complete bipartite graph of m white and m black vertices.Then l(G(n))=m and l(G(n))=m~2. It was conjectured that if G(n).has no isolated vertices then     

On the Approximation of Continuous Function by Harmonic Means

Let f(x) be a continuous and periodic function with period 2π and [f]=a_o/2+sum from n=1 to ∞(a_ncos nx+b_nsin nx) be its Fourier series. Denote by s_n(f,x) the n-th partial sums of [f] and by ω(f,δ) the moduls of continuity of f(x). When ω(δ) is a modul of continuity, we denote by H[ω]。the class of all functions for which ω(f,t)≤ω(t). It is well known that the n-th harmonic means and the n-th Cesro means of f∈C_2, are defined as##属性不符     

AUTOMORPHISMS OF SL (2, K) OVER SKEW FIELDS

In this paper, the author proves the following resu: It Let K be a skew field and A be an automorphism of SL(2, K). Then there exists A∈GL(2, K), an automorphism σ or an anti-automorphism τ of K, such that A is of theform AX=AX~σA~(-1) for all X∈SL(2, K)or AX=A(X~τ~2)~(-1)A~(-1) for all X∈SL(2, K),where X~σ, X~τ are the matrices obtained by applying σ, τ on X respee tively and X' is thetranspose of X.     

Representations of deformed preprojective algebras and quantum groups

Let (Γ,I) be the bound quiver of a cyclic quiver whose vertices correspond to the Abelian group Zd. In this paper, we list all indecomposable representations of (Γ,I) and give the conditions that those representations of them can be extended to representations of deformed preprojective algebra Πλ(Γ,I). It is shown that those representations given by extending indecomposable representations of (Γ,I) are all simple representations of Πλ(Γ,I). Therefore, it is concluded that all simple representa-tions of rest...     

RESEARCH ANNOUNCEMENTSOn the Simultaneous Pell Equations x~2-D_(1y)~2=δ and z~2 - D_(2y)~2 =δ

Let Z, N, Q be the sets of all integers, positive integers and rational numbers, respectively.Let D1, D2 be distinct positive integers, and let . The simultaneous Pell equationsarise in connection with a variety of classical problems on number theory and arithmetic algebraicgeometry. As has been noted by K. One[1], the solutions (x, y, z) of (1) imply the existence ofrational points of infinite order on the elliptic curveLet p, q be twin primes withRecently, Qiu Derong and Zhang Xianke[2…     

On Dynamics of Infinitely Generated Contractive Mapping Systems on pZ_p

Let p ≥ 2 be a prime number and Z_(p) be the ring of p-adic intergers. Let G be a semigroup generated by infinitely many contractive maps on p Z_(p). It is shown that if G satisfies the open tiling conditions, then there exists a shift transformation on the limit set of G and the shift transformation is ergodic with respect to the Haar measure on p Z_(p). As an application, we can generalize p-adic Khinchin's Theorem and p-adic Lochs' Theorem to any infinitely generated semigroup by use of the ergodicity of the shift transformation.     

A NEW TYPE OF PRONORMAT SUBGROUPS IN CHEVALLEY GROUPS

51. IntroductionNotation in this paper follows [2,3]. Let L be a simple Lie algebra over an algebraicclosed field of characteristic 0,. its root system with a ford base A = {afl, or2,', al},and W the Weyl group of L. . (.--) denotes the set of all the positive (negative) roots.Each s E ac can be written piquely in the form 8 = Z aam with all the coefficients beingaamintegers. Moreover, either all ac 2 0 or all ac S 0. The sum Z ac of all these coefficielltsaamis called the height of 8, …     

THE EIGENVALUE PROBLEM EQUIVALENT TO MULTIVARIATE POLYNOMIAL SYSTEM

In this paper, the authors proved that finding all solutions of a given multivariate polynomial system is equivalent to solving a relative joint eigenvalue problem(Theorem 1) and in some cases one can find all solutions of the given system from the eigenvalues and vectors of one matrix or matrix pencil (Theorem 2). Especially the situation that the ideal generated by the given system is 0-dimensional is discussed.     

一类体上SL_2(K)的自同构

<正> §1 引言 设K是任意一个体,K表示其乘法群,K~c表示其乘法群的换位子群,即K~c=[K,K].K上全体二阶非退化矩阵组成的群记为GL_2(K).由下列集合生成的GL_2(K)的子群,记为SL_2(K):     

On maximal injective subalgebras in a wΓ factor

Let L(FQ) ×α Z be the crossed product von Neumann algebra of the free group factor L(FQ), associated with the left regular representation λ of the free group FQ with the set {ur : r ∈ Q} of generators, by an automorphism α defined by α(λ(ur)) = exp(2πri)λ(ur), where Q is the rational number set. We show that L(FQ) ×α Z is a wΓ factor, and for each r ∈ Q, the von Neumann subalgebra Ar generated in L(FQ) ×α Z by λ(ur) and v is maximal injective, where v is the unitary implementing the automorphism α. In parti...