整系数射影么模羣的自同构

<正> §1.序言 以表行列式之值为±1的n×n整系数矩陣所組成的乘法羣,而以表中行列式之值为+1的矩陣所組成的子羣.的中核由{I,-I}所組成(I是单位矩阵).以表对其中核的商羣,称之为的射影羣.当n是偶数吋,的中核也是由{I,-I}所組成,以表对其中核之商羣,称之为整系数射影模羣. 华罗庚教授和I.Reiner在[1]中决定了,及(m≥1)的自同构.当n是奇     

The fixed points of coprime action

Let P be an odd p\pi -group that acts as a group of automorphisms on the soluble p￠\pi '-group G. We obtain generators for the fixed points of P on [G, P].     

Ad-Nilpotent Elements,Isomorphisms, and the Weisfeiler Filtration of Infinite-Dimensional Modular Odd Contact Superalgebras

The Weisfeiler filtrations of infinite-dimensional odd contact superalgebras over fields of positive characteristic are proved to be invariant under automorphisms by characterizing ad-nilpotent elements. Thereby, we are able to obtain an intrinsic characterization of odd contact superalgebras and a property of automorphisms of these Lie superalgebras.     

Infinite Families of Regular, Aspherical Two-Complexes with the Same Euler Characteristic

A regular 2-complex has a group of cellular automorphisms whichis transitive on 2-cells. Let p bean odd prime. By generalizingan example of Floyd and Parry [5], we obtain infinite familiesof compact, aspherical, regular 2-complexes with Euler characteristicp and infinite hyperbolic fundamental group. 1991 MathematicsSubject Classification 20F32, 57M20, 05C25.     

Filtration, automorphisms, and classification of infinite-dimensional odd contact superalgebras

The principal filtration of the infinite-dimensional odd contact Lie superalgebra over a field of characteristic p>2 is proved to be invariant under the automorphism group by investigating ad-nilpotent elements and determining certain invariants such as subalgebras generated by some ad-nilpotent elements. Then, it is proved that two automorphisms coincide if and only if they coincide on the -1 component with respect to the principal grading. Finally, all the odd contact superalgebras are classified up to isomorphisms.     

Automorphisms of groups of orderp 5

We study automorphisms of groups of orderp ⁵ (p is an odd prime number). Groups without any automorphism of order 2 and groups with group automorphisms of orderp ⁶ are found.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 47, No. 4, pp. 562–565, April, 1995.     

Splitting automorphisms of order p k of free Burnside groups are inner

It is proved that, if the order of a splitting automorphism of odd period n ≥ 1003 of a free Burnside group B(m, n) is equal to a power of some prime, then the automorphism is inner. Thus, an affirmative answer is given to the question concerning the coincidence of the splitting automorphisms of the group B(m, n) with the inner automorphisms for all automorphisms of order p ^k (p is a prime). This question was posed in 1990 in “Kourovka Notebook” (see the 11th edition, Question 11.36.b).     

Complete regular dessins of odd prime power order

A dessin is a 2-cell embedding of a connected 2-coloured bipartite graph into an orientable closed surface. A dessin is regular if its group of colour- and orientation-preserving automorphisms acts regularly on the edges. In this paper we employ group-theoretic method to determine and enumerate the isomorphism classes of regular dessins with complete bipartite underlying graphs of odd prime power order.     

2-(31,15,7), 2-(35,17,8) and 2-(36,15,6) designs with automorphisms of odd prime order,and their related Hadamard matrices and codes

We present the full classification of Hadamard 2-(31,15,7), Hadamard 2-(35, 17,8) and Menon 2-(36,15,6) designs with automorphisms of odd prime order. We also give partial classifications of such designs with automorphisms of order 2. These classifications lead to related Hadamard matrices and self-dual codes. We found 76166 Hadamard matrices of order 32 and 38332 Hadamard matrices of order 36, arising from the classified designs. Remarkably, all constructed Hadamard matrices of order 36 are Hadamard equivalent to a regular Hadamard matrix. From our constructed designs, we obtained 37352 doubly-even [72,36,12] codes, which are the best known self-dual codes of this length until now.      

On the automorphism groups of a special class of quasigroups

We investigate automorphism groups of 2-generated quasigroups, constructed in [6], and show that such quasigroups of odd order k ≥ 7 have only one nontrivial automorphism, whereas in the case of even order k ≥ 6 there are no nontrivial automorphisms.     

Enumeration of the doubles of the projective plane of order 4

A classification of the doubles of the projective plane of order 4 with respect to the order of the automorphism group is presented and it is established that, up to isomorphism, there are 1 746 461 307 doubles. We start with the designs possessing non-trivial automorphisms. Since the designs with automorphisms of odd prime orders have been constructed previously, we are left with the construction of the designs with automorphisms of order 2. Moreover, we establish that a 2-(21,5,2) design cannot be reducible in two inequivalent ways. This makes it possible to calculate the number of designs with only the trivial automorphism, and consequently the number of all double designs. Most of the computer results are obtained by two different approaches and implementations.     

Hamming spaces and maximal self dual codes over GF(q), q=ODD

The group of automorphisms of a Hamming space is determined. Self dual codes over odd characteristic finite field with respect to bilinear forms are treated. Under the subgroup of the monomial group preserving the inner product, we classify the maximal self dual codes overGF(5) with respect to the inner product of dimension ≤8. The Hamming Weight distribution and the order of the automorphism of the code are given. Partially supported by NSERC A8460 and Scarborough College.     

New classes of test polynomials of polynomial algebras

A polynomialp in a polynomial algebra over a field is called a test polynomial if any endomorphism of the polynomial algebra that fixesp is an automorphism. some classes of new test polynomials recognizing nonlinear automorphisms of polynomial algebras are given. In the odd prime characteristic case, test polynomials recognizing non-semisimple automorphisms are also constructed. Project supported by the National Natural Science Foundation of China (Grant No. 19631100) and University of Hong Kong RGC Fundable Grant 344/024/0004.     

Arc-regular cubic graphs of order four times an odd integer

A graph is arc-regular if its automorphism group acts sharply-transitively on the set of its ordered edges. This paper answers an open question about the existence of arc-regular 3-valent graphs of order 4m where m is an odd integer. Using the Gorenstein?CWalter theorem, it is shown that any such graph must be a normal cover of a base graph, where the base graph has an arc-regular group of automorphisms that is isomorphic to a subgroup of Aut(PSL(2,q)) containing PSL(2,q) for some odd prime-power?q. Also a construction is given for infinitely many such graphs??namely a family of Cayley graphs for the groups PSL(2,p ³) where p is an odd prime; the smallest of these has order?9828.     

Exceptional group ring automorphisms for some metabelian groups

Let H be a generalized dihedral, semi-dihedral, quaternion, or modular group, and let A = (u, v, w) be a product of three odd order cyclic groups, with (|v|,|w|) = 1. For R a semi-local Dedekind domain of characteristic 0 in which no prime divisor of |H|.|A| is invertible, we prove that there is a semi-direct product G = H × A such that the group ring RG has an exceptional automorphism, i.e. provides a counter-example to a well-known conjecture of Zassenhaus on automorphisms of group rings     

Cyclic automorphisms of a countable graph and random sum-free sets

Cyclic automorphisms of the countable universal ultrahomogeneous graph are investigated using methods of Baire category and measure theory. This leads to the study of random sumfree sets; it is shown that the probability that such a set consists entirely of odd numbers is strictly positive, and bounds are given.     

The Autotopism Group of A Semifield of Order p 4, p is an Odd Prime

The aim of this article is to investigate the autotopism group of a semifield of order p ⁴, p is an odd prime, admitting a four-group of automorphisms E? Z ₂ × Z ₂ acting freely on A.     

Self-duality of chiral polytopes

We prove that self-dual chiral polytopes of odd rank possess a polarity, that is, an involutory duality, and give an example showing this is not true in even ranks. Properties of the extended groups, that is of the groups of automorphisms and dualities, of self-dual chiral polytopes are discussed in detail.     

Polish topologies for graph products of cyclic groups

We give a complete characterization of the graph products of cyclic groups admitting a Polish group topology, and show that they are all realizable as the group of automorphisms of a countable structure. In particular, we characterize the right-angled Coxeter groups (resp. Artin groups) admitting a Polish group topology. This generalizes results from [8], [9] and [4].     

On the automorphisms of circular and Reinhardt domains in complex banach spaces

The group Aut(D) of all biholomorphic automorphisms of a bounded circular domain D in a complex Banach space E is discussed. As an application the group Aut[D] is computed for the open unit balls of certain classical Banach spaces.