Janko's Sporadic Simple Groups
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Math 411 Midterm 2, Thursday 11/17/11, 7PM-8:30PM. Instructions: Exam Time Is 90 Mins
Math 411 Midterm 2, Thursday 11/17/11, 7PM-8:30PM. Instructions: Exam time is 90 mins. There are 7 questions for a total of 75 points. Calculators, notes, and textbook are not allowed. Justify all your answers carefully. If you use a result proved in the textbook or class notes, state the result precisely. 1 Q1. (10 points) Let σ 2 S9 be the permutation 1 2 3 4 5 6 7 8 9 5 8 7 2 3 9 1 4 6 (a) (2 points) Write σ as a product of disjoint cycles. (b) (2 points) What is the order of σ? (c) (2 points) Write σ as a product of transpositions. (d) (4 points) Compute σ100. Q2. (8 points) (a) (3 points) Find an element of S5 of order 6 or prove that no such element exists. (b) (5 points) Find an element of S6 of order 7 or prove that no such element exists. Q3. (12 points) (a) (4 points) List all the elements of the alternating group A4. (b) (8 points) Find the left cosets of the subgroup H of A4 given by H = fe; (12)(34); (13)(24); (14)(23)g: Q4. (10 points) (a) (3 points) State Lagrange's theorem. (b) (7 points) Let p be a prime, p ≥ 3. Let Dp be the dihedral group of symmetries of a regular p-gon (a polygon with p sides of equal length). What are the possible orders of subgroups of Dp? Give an example in each case. 2 Q5. (13 points) (a) (3 points) State a theorem which describes all finitely generated abelian groups. -
Generating the Mathieu Groups and Associated Steiner Systems
View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Elsevier - Publisher Connector Discrete Mathematics 112 (1993) 41-47 41 North-Holland Generating the Mathieu groups and associated Steiner systems Marston Conder Department of Mathematics and Statistics, University of Auckland, Private Bag 92019, Auckland, New Zealand Received 13 July 1989 Revised 3 May 1991 Abstract Conder, M., Generating the Mathieu groups and associated Steiner systems, Discrete Mathematics 112 (1993) 41-47. With the aid of two coset diagrams which are easy to remember, it is shown how pairs of generators may be obtained for each of the Mathieu groups M,,, MIz, Mz2, M,, and Mz4, and also how it is then possible to use these generators to construct blocks of the associated Steiner systems S(4,5,1 l), S(5,6,12), S(3,6,22), S(4,7,23) and S(5,8,24) respectively. 1. Introduction Suppose you land yourself in 24-dimensional space, and are faced with the problem of finding the best way to pack spheres in a box. As is well known, what you really need for this is the Leech Lattice, but alas: you forgot to bring along your Miracle Octad Generator. You need to construct the Leech Lattice from scratch. This may not be so easy! But all is not lost: if you can somehow remember how to define the Mathieu group Mz4, you might be able to produce the blocks of a Steiner system S(5,8,24), and the rest can follow. In this paper it is shown how two coset diagrams (which are easy to remember) can be used to obtain pairs of generators for all five of the Mathieu groups M,,, M12, M22> Mz3 and Mz4, and also how blocks may be constructed from these for each of the Steiner systems S(4,5,1 I), S(5,6,12), S(3,6,22), S(4,7,23) and S(5,8,24) respectively. -
On the Classification of Finite Simple Groups
On the Classification of Finite Simple Groups Niclas Bernhoff Division for Engineering Sciences, Physics and Mathemathics Karlstad University April6,2004 Abstract This paper is a small note on the classification of finite simple groups for the course ”Symmetries, Groups and Algebras” given at the Depart- ment of Physics at Karlstad University in the Spring 2004. 1Introduction In 1892 Otto Hölder began an article in Mathematische Annalen with the sen- tence ”It would be of the greatest interest if it were possible to give an overview of the entire collection of finite simple groups” (translation from German). This can be seen as the starting point of the classification of simple finite groups. In 1980 the following classification theorem could be claimed. Theorem 1 (The Classification theorem) Let G be a finite simple group. Then G is either (a) a cyclic group of prime order; (b) an alternating group of degree n 5; (c) a finite simple group of Lie type;≥ or (d) one of 26 sporadic finite simple groups. However, the work comprises in total about 10000-15000 pages in around 500 journal articles by some 100 authors. This opens for the question of possible mistakes. In fact, around 1989 Aschbacher noticed that an 800-page manuscript on quasithin groups by Mason was incomplete in various ways; especially it lacked a treatment of certain ”small” cases. Together with S. Smith, Aschbacher is still working to finish this ”last” part of the proof. Solomon predicted this to be finished in 2001-2002, but still until today the paper is not completely finished (see the homepage of S. -
Classification of Finite Abelian Groups
Math 317 C1 John Sullivan Spring 2003 Classification of Finite Abelian Groups (Notes based on an article by Navarro in the Amer. Math. Monthly, February 2003.) The fundamental theorem of finite abelian groups expresses any such group as a product of cyclic groups: Theorem. Suppose G is a finite abelian group. Then G is (in a unique way) a direct product of cyclic groups of order pk with p prime. Our first step will be a special case of Cauchy’s Theorem, which we will prove later for arbitrary groups: whenever p |G| then G has an element of order p. Theorem (Cauchy). If G is a finite group, and p |G| is a prime, then G has an element of order p (or, equivalently, a subgroup of order p). ∼ Proof when G is abelian. First note that if |G| is prime, then G = Zp and we are done. In general, we work by induction. If G has no nontrivial proper subgroups, it must be a prime cyclic group, the case we’ve already handled. So we can suppose there is a nontrivial subgroup H smaller than G. Either p |H| or p |G/H|. In the first case, by induction, H has an element of order p which is also order p in G so we’re done. In the second case, if ∼ g + H has order p in G/H then |g + H| |g|, so hgi = Zkp for some k, and then kg ∈ G has order p. Note that we write our abelian groups additively. Definition. Given a prime p, a p-group is a group in which every element has order pk for some k. -
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. -
Orders on Computable Torsion-Free Abelian Groups
Orders on Computable Torsion-Free Abelian Groups Asher M. Kach (Joint Work with Karen Lange and Reed Solomon) University of Chicago 12th Asian Logic Conference Victoria University of Wellington December 2011 Asher M. Kach (U of C) Orders on Computable TFAGs ALC 2011 1 / 24 Outline 1 Classical Algebra Background 2 Computing a Basis 3 Computing an Order With A Basis Without A Basis 4 Open Questions Asher M. Kach (U of C) Orders on Computable TFAGs ALC 2011 2 / 24 Torsion-Free Abelian Groups Remark Disclaimer: Hereout, the word group will always refer to a countable torsion-free abelian group. The words computable group will always refer to a (fixed) computable presentation. Definition A group G = (G : +; 0) is torsion-free if non-zero multiples of non-zero elements are non-zero, i.e., if (8x 2 G)(8n 2 !)[x 6= 0 ^ n 6= 0 =) nx 6= 0] : Asher M. Kach (U of C) Orders on Computable TFAGs ALC 2011 3 / 24 Rank Theorem A countable abelian group is torsion-free if and only if it is a subgroup ! of Q . Definition The rank of a countable torsion-free abelian group G is the least κ cardinal κ such that G is a subgroup of Q . Asher M. Kach (U of C) Orders on Computable TFAGs ALC 2011 4 / 24 Example The subgroup H of Q ⊕ Q (viewed as having generators b1 and b2) b1+b2 generated by b1, b2, and 2 b1+b2 So elements of H look like β1b1 + β2b2 + α 2 for β1; β2; α 2 Z. -
Dihedral Groups Ii
DIHEDRAL GROUPS II KEITH CONRAD We will characterize dihedral groups in terms of generators and relations, and describe the subgroups of Dn, including the normal subgroups. We will also introduce an infinite group that resembles the dihedral groups and has all of them as quotient groups. 1. Abstract characterization of Dn −1 −1 The group Dn has two generators r and s with orders n and 2 such that srs = r . We will show every group with a pair of generators having properties similar to r and s admits a homomorphism onto it from Dn, and is isomorphic to Dn if it has the same size as Dn. Theorem 1.1. Let G be generated by elements x and y where xn = 1 for some n ≥ 3, 2 −1 −1 y = 1, and yxy = x . There is a surjective homomorphism Dn ! G, and if G has order 2n then this homomorphism is an isomorphism. The hypotheses xn = 1 and y2 = 1 do not mean x has order n and y has order 2, but only that their orders divide n and divide 2. For instance, the trivial group has the form hx; yi where xn = 1, y2 = 1, and yxy−1 = x−1 (take x and y to be the identity). Proof. The equation yxy−1 = x−1 implies yxjy−1 = x−j for all j 2 Z (raise both sides to the jth power). Since y2 = 1, we have for all k 2 Z k ykxjy−k = x(−1) j by considering even and odd k separately. Thus k (1.1) ykxj = x(−1) jyk: This shows each product of x's and y's can have all the x's brought to the left and all the y's brought to the right. -
Sporadic Sics and Exceptional Lie Algebras
Sporadic SICs and Exceptional Lie Algebras Blake C. Staceyy yQBism Group, Physics Department, University of Massachusetts Boston, 100 Morrissey Boulevard, Boston MA 02125, USA November 13, 2019 Abstract Sometimes, mathematical oddities crowd in upon one another, and the exceptions to one classification scheme reveal themselves as fellow-travelers with the exceptions to a quite different taxonomy. 1 Preliminaries A set of equiangular lines is a set of unit vectors in a d-dimensional vector space such that the magnitude of the inner product of any pair is constant: 1; j = k; jhv ; v ij = (1) j k α; j 6= k: The maximum number of equiangular lines in a space of dimension d (the so-called Gerzon bound) is d(d+1)=2 for real vector spaces and d2 for complex. In the real case, the Gerzon bound is only known to be attained in dimensions 2, 3, 7 and 23, and we know it can't be attained in general. If you like peculiar alignments of mathematical topics, the appearance of 7 and 23 might make your ears prick up here. If you made the wild guess that the octonions and the Leech lattice are just around the corner. you'd be absolutely right. Meanwhile, the complex case is of interest for quantum information theory, because a set of d2 equiangular lines in Cd specifies a measurement that can be performed upon a quantum-mechanical system. These measurements are highly symmetric, in that the lines which specify them are equiangular, and they are \informationally complete" in a sense that quantum theory makes precise. -
A Natural Representation of the Fischer-Griess Monster
Proc. Nati. Acad. Sci. USA Vol. 81, pp. 3256-3260, May 1984 Mathematics A natural representation of the Fischer-Griess Monster with the modular function J as character (vertex operators/finite simple group Fl/Monstrous Moonshine/affine Lie algebras/basic modules) I. B. FRENKEL*t, J. LEPOWSKY*t, AND A. MEURMANt *Department of Mathematics, Rutgers University, New Brunswick, NJ 08903; and tMathematical Sciences Research Institute, Berkeley, CA 94720 Communicated by G. D. Mostow, February 3, 1984 ABSTRACT We announce the construction of an irreduc- strange discoveries could make sense. However, instead of ible graded module V for an "affine" commutative nonassocia- illuminating the mysteries, he added a new one, by con- tive algebra S. This algebra is an "affinization" of a slight structing a peculiar commutative nonassociative algebra B variant R of the conMnutative nonassociative algebra B de- and proving directly that its automorphism group contains fined by Griess in his construction of the Monster sporadic F1. group F1. The character of V is given by the modular function The present work started as an attempt to explain the ap- J(q) _ q' + 0 + 196884q + .... We obtain a natural action of pearance of J(q) as well as the structure of B. Our under- the Monster on V compatible with the action of R, thus con- standing of these phenomena has now led us to conceptual ceptually explaining a major part of the numerical observa- constructions of several objects: V; a variant a of B; an "af- tions known as Monstrous Moonshine. Our construction starts finization" 9a of@a; and F1, which appears as a group of oper- from ideas in the theory of the basic representations of affine ators on V and at the sajne time as a group of algebra auto- Lie algebras and develops further the cadculus of vertex opera- morphisms of R and of 9a. -
A History of Mathematics in America Before 1900.Pdf
THE BOOK WAS DRENCHED 00 S< OU_1 60514 > CD CO THE CARUS MATHEMATICAL MONOGRAPHS Published by THE MATHEMATICAL ASSOCIATION OF AMERICA Publication Committee GILBERT AMES BLISS DAVID RAYMOND CURTISS AUBREY JOHN KEMPNER HERBERT ELLSWORTH SLAUGHT CARUS MATHEMATICAL MONOGRAPHS are an expression of THEthe desire of Mrs. Mary Hegeler Carus, and of her son, Dr. Edward H. Carus, to contribute to the dissemination of mathe- matical knowledge by making accessible at nominal cost a series of expository presenta- tions of the best thoughts and keenest re- searches in pure and applied mathematics. The publication of these monographs was made possible by a notable gift to the Mathematical Association of America by Mrs. Carus as sole trustee of the Edward C. Hegeler Trust Fund. The expositions of mathematical subjects which the monographs will contain are to be set forth in a manner comprehensible not only to teach- ers and students specializing in mathematics, but also to scientific workers in other fields, and especially to the wide circle of thoughtful people who, having a moderate acquaintance with elementary mathematics, wish to extend their knowledge without prolonged and critical study of the mathematical journals and trea- tises. The scope of this series includes also historical and biographical monographs. The Carus Mathematical Monographs NUMBER FIVE A HISTORY OF MATHEMATICS IN AMERICA BEFORE 1900 By DAVID EUGENE SMITH Professor Emeritus of Mathematics Teacliers College, Columbia University and JEKUTHIEL GINSBURG Professor of Mathematics in Yeshiva College New York and Editor of "Scripta Mathematica" Published by THE MATHEMATICAL ASSOCIATION OF AMERICA with the cooperation of THE OPEN COURT PUBLISHING COMPANY CHICAGO, ILLINOIS THE OPEN COURT COMPANY Copyright 1934 by THE MATHEMATICAL ASSOCIATION OF AMKRICA Published March, 1934 Composed, Printed and Bound by tClfe QlolUgUt* $Jrr George Banta Publishing Company Menasha, Wisconsin, U. -
Biased Tadpoles: a Fast Algorithm for Centralizers in Large Matrix Groups
Biased Tadpoles: a Fast Algorithm for Centralizers in Large Matrix Groups Daniel Kunkle and Gene Cooperman College of Computer and Information Science Northeastern University Boston, MA, USA [email protected], [email protected] ABSTRACT of basis formula in linear algebra. Given a group G, the def Centralizers are an important tool in in computational group centralizer subgroup of g G is defined as G(g) = h: h h ∈ C { ∈ theory. Yet for large matrix groups, they tend to be slow. G, g = g . } We demonstrate a O(p G (1/ log ε)) black box randomized Note that the above definition of centralizer is well-defined algorithm that produces| a| centralizer using space logarith- independently of the representation of G. Even for permu- mic in the order of the centralizer, even for typical matrix tation group representations, it is not known whether the groups of order 1020. An optimized version of this algorithm centralizer problem can be solved in polynomial time. Nev- (larger space and no longer black box) typically runs in sec- ertheless, in the permutation group case, Leon produced a onds for groups of order 1015 and minutes for groups of or- partition backtrack algorithm [8, 9] that is highly efficient der 1020. Further, the algorithm trivially parallelizes, and so in practice both for centralizer problems and certain other linear speedup is achieved in an experiment on a computer problems also not known to be in polynomial time. Theißen with four CPU cores. The novelty lies in the use of a bi- produced a particularly efficient implementation of partition ased tadpole, which delivers an order of magnitude speedup backtrack for GAP [17]. -
New Criteria for the Solvability of Finite Groups
CORE Metadata, citation and similar papers at core.ac.uk Provided by Elsevier - Publisher Connector JOURNAL OF ALGEBRA 77. 234-246 (1982) New Criteria for the Solvability of Finite Groups ZVI ARAD DePartment of Malhematics, Bar-llan Utzioersity. Kamat-Gun. Israel AND MICHAEL B. WARD Department of Mathemalics, Bucknell University, Lewisburg, Penrtsylcania I7837 Communicared by Waher Feif Received September 27. 1981 1. INTRODUCTION All groups considered in this paper are finite. Suppose 7~is a set of primes. A subgroup H of a group G is called a Hall 7r-subgroup of G if every prime dividing ] HI is an element of x and no prime dividing [G : H ] is an element of 71.When p is a prime, p’ denotes the set of all primes different from p. In Hall’s famous characterization of solvable groups he proves that a group is solvable if and only if it has a Hall p’-subgroup for each prime p (see [6] or [ 7, p. 291]). It has been conjectured that a group is solvable if and only if it has a Hall 2’-subgroup and a Hall 3’subgroup (see [ 11). We verify this conjecture for groups whose composition factors are known simple groups. Along the way we also verify (for groups whose composition factors are known simple groups) a conjecture of Hall’s that if a group has a Hall ( p, q}-subgroup for every pair of primes p, 9, then the group is solvable [7, p. 2911. Thus, if one assumes the classification of finite simple groups, then both of these conjectures are settled in the affirmative.