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On Some Generation Methods of Finite Simple Groups
Introduction Preliminaries Special Kind of Generation of Finite Simple Groups The Bibliography On Some Generation Methods of Finite Simple Groups Ayoub B. M. Basheer Department of Mathematical Sciences, North-West University (Mafikeng), P Bag X2046, Mmabatho 2735, South Africa Groups St Andrews 2017 in Birmingham, School of Mathematics, University of Birmingham, United Kingdom 11th of August 2017 Ayoub Basheer, North-West University, South Africa Groups St Andrews 2017 Talk in Birmingham Introduction Preliminaries Special Kind of Generation of Finite Simple Groups The Bibliography Abstract In this talk we consider some methods of generating finite simple groups with the focus on ranks of classes, (p; q; r)-generation and spread (exact) of finite simple groups. We show some examples of results that were established by the author and his supervisor, Professor J. Moori on generations of some finite simple groups. Ayoub Basheer, North-West University, South Africa Groups St Andrews 2017 Talk in Birmingham Introduction Preliminaries Special Kind of Generation of Finite Simple Groups The Bibliography Introduction Generation of finite groups by suitable subsets is of great interest and has many applications to groups and their representations. For example, Di Martino and et al. [39] established a useful connection between generation of groups by conjugate elements and the existence of elements representable by almost cyclic matrices. Their motivation was to study irreducible projective representations of the sporadic simple groups. In view of applications, it is often important to exhibit generating pairs of some special kind, such as generators carrying a geometric meaning, generators of some prescribed order, generators that offer an economical presentation of the group. -
Crystal Symmetry Groups
X-Ray and Neutron Crystallography rational numbers is a group under Crystal Symmetry Groups multiplication, and both it and the integer group already discussed are examples of infinite groups because they each contain an infinite number of elements. ymmetry plays an important role between the integers obey the rules of In the case of a symmetry group, in crystallography. The ways in group theory: an element is the operation needed to which atoms and molecules are ● There must be defined a procedure for produce one object from another. For arrangeds within a unit cell and unit cells example, a mirror operation takes an combining two elements of the group repeat within a crystal are governed by to form a third. For the integers one object in one location and produces symmetry rules. In ordinary life our can choose the addition operation so another of the opposite hand located first perception of symmetry is what that a + b = c is the operation to be such that the mirror doing the operation is known as mirror symmetry. Our performed and u, b, and c are always is equidistant between them (Fig. 1). bodies have, to a good approximation, elements of the group. These manipulations are usually called mirror symmetry in which our right side ● There exists an element of the group, symmetry operations. They are com- is matched by our left as if a mirror called the identity element and de- bined by applying them to an object se- passed along the central axis of our noted f, that combines with any other bodies. -
The Cohomologies of the Sylow 2-Subgroups of a Symplectic Group of Degree Six and of the Third Conway Group
THE COHOMOLOGIES OF THE SYLOW 2-SUBGROUPS OF A SYMPLECTIC GROUP OF DEGREE SIX AND OF THE THIRD CONWAY GROUP JOHN MAGINNIS Abstract. The third Conway group Co3 is one of the twenty-six sporadic finite simple groups. The cohomology of its Sylow 2-subgroup S is computed, an important step in calculating the mod 2 cohomology of Co3. The spectral sequence for the central extension of S is described and collapses at the sixth page. Generators are described in terms of the Evens norm or transfers from subgroups. The central quotient S0 = S=2 is the Sylow 2-subgroup of the symplectic group Sp6(F2) of six by six matrices over the field of two elements. The cohomology of S0 is computed, and is detected by restriction to elementary abelian 2-subgroups. 1. Introduction A presentation for the Sylow 2-subgroup S of the sporadic finite simple group Co3 is given by Benson [1]. We will use a different presentation, with generators which can be described in terms of Benson's generators fa1; a2; a3; a4; b1; b2; c1; c2; eg as follows. w = c3; x = b2c1c2; y = ec3; z = a4; a = a3a4c2; b = a3a4b1c2; c = a3; t = a4c1; u = a2; v = a1: We have the following set of relations for the generators fw; x; y; z; a; b; c; t; u; vg. w2 = x2 = y2 = z2 = c2 = u2 = v2 = [w; y] = [w; z] = [w; c] = [w; v] = [x; z] = [x; u] = [x; v] = [y; c] = [y; u] = [y; v] = [a; z] = [c; z] = [u; z] = [v; z] = [c; t] = [c; u] = [c; v] = [a; u] = [a; v] = [b; c] = [b; t] = [b; u] = [b; v] = [t; u] = [t; v] = [u; v] = 1; tu = [a; y]; t = [w; b]; av = [w; x]; b = [x; y]; c = [y; z] u = b2 = [x; c] = [b; z] = [b; y] = [b; x]; uv = [t; x] = [a; b]; v = t2 = a2 = [w; u] = [a; c] = [t; z] = [a; w] = [t; w] = [t; a] = [t; y] = [a; x]: The group S has order 1024 and a center Z(S) of order two, generated by v = a1. -
Chapter 25 Finite Simple Groups
Chapter 25 Finite Simple Groups Chapter 25 Finite Simple Groups Historical Background Definition A group is simple if it has no nontrivial proper normal subgroup. The definition was proposed by Galois; he showed that An is simple for n ≥ 5 in 1831. It is an important step in showing that one cannot express the solutions of a quintic equation in radicals. If possible, one would factor a group G as G0 = G, find a normal subgroup G1 of maximum order to form G0/G1. Then find a maximal normal subgroup G2 of G1 and get G1/G2, and so on until we get the composition factors: G0/G1,G1/G2,...,Gn−1/Gn, with Gn = {e}. Jordan and Hölder proved that these factors are independent of the choices of the normal subgroups in the process. Jordan in 1870 found four infinite series including: Zp for a prime p, SL(n, Zp)/Z(SL(n, Zp)) except when (n, p) = (2, 2) or (2, 3). Between 1982-1905, Dickson found more infinite series; Miller and Cole showed that 5 (sporadic) groups constructed by Mathieu in 1861 are simple. Chapter 25 Finite Simple Groups In 1950s, more infinite families were found, and the classification project began. Brauer observed that the centralizer has an order 2 element is important; Feit-Thompson in 1960 confirmed the 1900 conjecture that non-Abelian simple group must have even order. From 1966-75, 19 new sporadic groups were found. Thompson developed many techniques in the N-group paper. Gorenstein presented an outline for the classification project in a lecture series at University of Chicago in 1972. -
Prescribed Gauss Decompositions for Kac-Moody Groups Over Fields
RENDICONTI del SEMINARIO MATEMATICO della UNIVERSITÀ DI PADOVA JUN MORITA EUGENE PLOTKIN Prescribed Gauss decompositions for Kac- Moody groups over fields Rendiconti del Seminario Matematico della Università di Padova, tome 106 (2001), p. 153-163 <http://www.numdam.org/item?id=RSMUP_2001__106__153_0> © Rendiconti del Seminario Matematico della Università di Padova, 2001, tous droits réservés. L’accès aux archives de la revue « Rendiconti del Seminario Matematico della Università di Padova » (http://rendiconti.math.unipd.it/) implique l’accord avec les conditions générales d’utilisation (http://www.numdam.org/conditions). Toute utilisation commerciale ou impression systématique est constitutive d’une infraction pénale. Toute copie ou impression de ce fichier doit conte- nir la présente mention de copyright. Article numérisé dans le cadre du programme Numérisation de documents anciens mathématiques http://www.numdam.org/ Prescribed Gauss Decompositions for Kac-Moody Groups Over Fields. JUN MORITA(*) - EUGENE PLOTKIN (**) ABSTRACT - We obtain the Gauss decomposition with prescribed torus elements for a Kac-Moody group over a field containing sufficiently many elements. 1. Introduction. Kac-Moody groups are equipped with canonical decompositions of different types. Let us note, for instance, the decompositions of Bruhat, Birkhoff and Gauss. As in the finite dimensional case, they play an im- portant role in calculations with these groups. However, in the Kac-Moo- dy case each of these decompositions has its own special features (see, for example, [18] where J. Tits compares the Bruhat and the Birkhoff decompositions and presents some applications). The aim of this paper is to establish the so-called prescribed Gauss decomposition for Kac-Moody groups. -
A NEW APPROACH to UNRAMIFIED DESCENT in BRUHAT-TITS THEORY by Gopal Prasad
A NEW APPROACH TO UNRAMIFIED DESCENT IN BRUHAT-TITS THEORY By Gopal Prasad Dedicated to my wife Indu Prasad with gratitude Abstract. We present a new approach to unramified descent (\descente ´etale") in Bruhat-Tits theory of reductive groups over a discretely valued field k with Henselian valuation ring which appears to be conceptually simpler, and more geometric, than the original approach of Bruhat and Tits. We are able to derive the main results of the theory over k from the theory over the maximal unramified extension K of k. Even in the most interesting case for number theory and representation theory, where k is a locally compact nonarchimedean field, the geometric approach described in this paper appears to be considerably simpler than the original approach. Introduction. Let k be a field given with a nontrivial R-valued nonarchimedean valuation !. We will assume throughout this paper that the valuation ring × o := fx 2 k j !(x) > 0g [ f0g of this valuation is Henselian. Let K be the maximal unramified extension of k (the term “unramified extension" includes the condition that the residue field extension is separable, so the residue field of K is the separable closure κs of the residue field κ of k). While discussing Bruhat-Tits theory in this introduction, and beginning with 1.6 everywhere in the paper, we will assume that ! is a discrete valuation. Bruhat- Tits theory of connected reductive k-groups G that are quasi-split over K (i.e., GK contains a Borel subgroup, or, equivalently, the centralizer of a maximal K-split torus of GK is a torus) has two parts. -
Molecular Symmetry
Molecular Symmetry 1 I. WHAT IS SYMMETRY AND WHY IT IS IMPORTANT? Some object are ”more symmetrical” than others. A sphere is more symmetrical than a cube because it looks the same after rotation through any angle about the diameter. A cube looks the same only if it is rotated through certain angels about specific axes, such as 90o, 180o, or 270o about an axis passing through the centers of any of its opposite faces, or by 120o or 240o about an axis passing through any of the opposite corners. Here are also examples of different molecules which remain the same after certain symme- try operations: NH3, H2O, C6H6, CBrClF . In general, an action which leaves the object looking the same after a transformation is called a symmetry operation. Typical symme- try operations include rotations, reflections, and inversions. There is a corresponding symmetry element for each symmetry operation, which is the point, line, or plane with respect to which the symmetry operation is performed. For instance, a rotation is carried out around an axis, a reflection is carried out in a plane, while an inversion is carried our in a point. We shall see that we can classify molecules that possess the same set of symmetry ele- ments, and grouping together molecules that possess the same set of symmetry elements. This classification is very important, because it allows to make some general conclusions about molecular properties without calculation. Particularly, we will be able to decide if a molecule has a dipole moment, or not and to know in advance the degeneracy of molecular states. -
Near Polygons and Fischer Spaces
Near polygons and Fischer spaces Citation for published version (APA): Brouwer, A. E., Cohen, A. M., Hall, J. I., & Wilbrink, H. A. (1994). Near polygons and Fischer spaces. Geometriae Dedicata, 49(3), 349-368. https://doi.org/10.1007/BF01264034 DOI: 10.1007/BF01264034 Document status and date: Published: 01/01/1994 Document Version: Publisher’s PDF, also known as Version of Record (includes final page, issue and volume numbers) Please check the document version of this publication: • A submitted manuscript is the version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal. -
2 Cohomology Ring of the Third Conway Groupis Cohen--Macaulay
Algebraic & Geometric Topology 11 (2011) 719–734 719 The mod–2 cohomology ring of the third Conway group is Cohen–Macaulay SIMON AKING DAVID JGREEN GRAHAM ELLIS By explicit machine computation we obtain the mod–2 cohomology ring of the third Conway group Co3 . It is Cohen–Macaulay, has dimension 4, and is detected on the maximal elementary abelian 2–subgroups. 20J06; 20-04, 20D08 1 Introduction There has been considerable work on the mod–2 cohomology rings of the finite simple groups. Every finite simple group of 2–rank at most three has Cohen–Macaulay mod–2 cohomology by Adem and Milgram [2]. There are eight sporadic finite simple groups of 2–rank four. For six of these, Adem and Milgram already determined the mod–2 cohomology ring, at least as a module over a polynomial subalgebra [3, VIII.5]. In most cases the cohomology is not Cohen–Macaulay. For instance, the Mathieu groups M22 and M23 each have maximal elementary abelian 2–subgroups of ranks 3 and 4, meaning that the cohomology cannot be Cohen–Macaulay: see [3, page 269]. The two outstanding cases have the largest Sylow 2–subgroups. The Higman–Sims group HS has size 29 Sylow subgroup, and the cohomology of this 2–group is known 10 by Adem et al [1]. The third Conway group Co3 has size 2 Sylow subgroup. In this paper we consider Co3 . It stands out for two reasons, one being that it has the largest Sylow 2–subgroup. The second reason requires a little explanation. The Mathieu group M12 has 2–rank three. -
Special Unitary Group - Wikipedia
Special unitary group - Wikipedia https://en.wikipedia.org/wiki/Special_unitary_group Special unitary group In mathematics, the special unitary group of degree n, denoted SU( n), is the Lie group of n×n unitary matrices with determinant 1. (More general unitary matrices may have complex determinants with absolute value 1, rather than real 1 in the special case.) The group operation is matrix multiplication. The special unitary group is a subgroup of the unitary group U( n), consisting of all n×n unitary matrices. As a compact classical group, U( n) is the group that preserves the standard inner product on Cn.[nb 1] It is itself a subgroup of the general linear group, SU( n) ⊂ U( n) ⊂ GL( n, C). The SU( n) groups find wide application in the Standard Model of particle physics, especially SU(2) in the electroweak interaction and SU(3) in quantum chromodynamics.[1] The simplest case, SU(1) , is the trivial group, having only a single element. The group SU(2) is isomorphic to the group of quaternions of norm 1, and is thus diffeomorphic to the 3-sphere. Since unit quaternions can be used to represent rotations in 3-dimensional space (up to sign), there is a surjective homomorphism from SU(2) to the rotation group SO(3) whose kernel is {+ I, − I}. [nb 2] SU(2) is also identical to one of the symmetry groups of spinors, Spin(3), that enables a spinor presentation of rotations. Contents Properties Lie algebra Fundamental representation Adjoint representation The group SU(2) Diffeomorphism with S 3 Isomorphism with unit quaternions Lie Algebra The group SU(3) Topology Representation theory Lie algebra Lie algebra structure Generalized special unitary group Example Important subgroups See also 1 of 10 2/22/2018, 8:54 PM Special unitary group - Wikipedia https://en.wikipedia.org/wiki/Special_unitary_group Remarks Notes References Properties The special unitary group SU( n) is a real Lie group (though not a complex Lie group). -
Iiiiiiiumiiiiuuiiiuiiii~Iuumiiniuii
r.~M CBM ~~~y R ``' ~~o~~o~~`~~~~~~~~~ J~~~~o~ ~;~~~~~ 7626 J~~~~.~~ Qo5 ~oo ~~~, u 1990 iiiiiiiumiiiiuuiiiuiiii~iuumiini ii 458 ! A DESIGN AND A CODE INVARIANT UNDER THE SIMPLE GROUP Co3 Willem H. Haemers, Christopher Parker Vera Pless and Vladimir D. Tonchev r. 4 ~ ~,~' FEw 458 .J ~ ~ ~ A DESIGN AND A CODE INVARIANT UNDER THE SIMPLE GROUP Cos Willem H. Haemers Department of Economics, Tilburg University, P.O.Box 90153, 5000 LE Tilburg, The Netherlands, r Christopher Parker ) Department of Mathematics, University of Wisconsin-Parkside, Box 2000, Kenosha, Wisconsin 53141-2000, USA, Vera Pless, Department of Mathematics, University of Illinois at Chicago, Box 4348, Chicago, Illinois 60680, USA, and Vladimir D. Tonchev~) Institute of Mathematics, P.O. Box 373, 1090 Sofia, Bulgaria In memory of Professor Marshall Hall ABSTRACT A self-orthogonal doubly-even (276,23) code invariant under the Conway simple group Coa is constructed. The minimum weight codewords form a 2-(2~6,100,2. 3)~ doubly-transitive block-primitive design with block sta- bilizer isomorphic to the Higman-Sims simple group HS. More generally, the codewords of any given weight are single orbits stabilized by maximal subgroups of Cos. The restriction of the code on the complement of a mini- mum weight codeword is the (1~6,22) code discovered by Calderbank and Wales as a code invariant under HS. ~) Part of this work was done while these two authors were at the Univer- sity of Giessen, W. Germany, the first as a NATO Research Fellow, and the second as a Research Fellow of the Alexander von Humboldt Foundation. -
Recent Progress in the Symmetric Generation of Groups, to Appear in the Proceedings of the Conference Groups St Andrews 2009 [28] B
RECENT PROGRESS IN THE SYMMETRIC GENERATION OF GROUPS BEN FAIRBAIRN Abstract. Many groups possess highly symmetric generating sets that are naturally endowed with an underlying combinatorial struc- ture. Such generating sets can prove to be extremely useful both theoretically in providing new existence proofs for groups and prac- tically by providing succinct means of representing group elements. We give a survey of results obtained in the study of these symmet- ric generating sets. In keeping with earlier surveys on this matter, we emphasize the sporadic simple groups. ADDENDUM: This is an updated version of a survey article orig- inally accepted for inclusion in the proceedings of the 2009 ‘Groups St Andrews’ conference [27]. Since [27] was accepted the author has become aware of other recent work in the subject that we incorporate to provide an updated version here (the most notable addition being the contents of Section 3.4). 1. Introduction This article is concerned with groups that are generated by highly symmetric subsets of their elements: that is to say by subsets of el- ements whose set normalizer within the group they generate acts on them by conjugation in a highly symmetric manner. Rather than inves- tigate the behaviour of known groups we turn this procedure around and ask what groups can be generated by a set of elements that pos- sesses a certain assigned set of symmetries. This enables constructions arXiv:1004.2272v2 [math.GR] 21 Apr 2010 by hand of a number of interesting groups, including many of the spo- radic simple groups. Much of the emphasis of the research project to date has been concerned with using these techniques to construct spo- radic simple groups, and this article will emphasize this important spe- cial case.