Download or read book Q polynomial Structures for Association Schemes and Distance regular Graphs written by Garth A. Dickie and published by . This book was released on 1995 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Distance Regular Graphs written by Andries E. Brouwer and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 513 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ever since the discovery of the five platonic solids in ancient times, the study of symmetry and regularity has been one of the most fascinating aspects of mathematics. Quite often the arithmetical regularity properties of an object imply its uniqueness and the existence of many symmetries. This interplay between regularity and symmetry properties of graphs is the theme of this book. Starting from very elementary regularity properties, the concept of a distance-regular graph arises naturally as a common setting for regular graphs which are extremal in one sense or another. Several other important regular combinatorial structures are then shown to be equivalent to special families of distance-regular graphs. Other subjects of more general interest, such as regularity and extremal properties in graphs, association schemes, representations of graphs in euclidean space, groups and geometries of Lie type, groups acting on graphs, and codes are covered independently. Many new results and proofs and more than 750 references increase the encyclopaedic value of this book.
Download or read book Algebraic Combinatorics I written by Eiichi Bannai and published by Addison-Wesley Longman. This book was released on 1984-01-21 with total page 464 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Bipartite P and Q polynomial Association Schemes written by John Simon Caughman and published by . This book was released on 1998 with total page 234 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Association Schemes written by R. A. Bailey and published by Cambridge University Press. This book was released on 2004-02-26 with total page 410 pages. Available in PDF, EPUB and Kindle. Book excerpt: Association schemes are of interest to both mathematicians and statisticians and this book was written with both audiences in mind. For statisticians, it shows how to construct designs for experiments in blocks, how to compare such designs, and how to analyse data from them. The reader is only assumed to know very basic abstract algebra. For pure mathematicians, it tells why association schemes are important and develops the theory to the level of advanced research. This book arose from a course successfully taught by the author and as such the material is thoroughly class-tested. There are a great number of examples and exercises that will increase the book's appeal to both graduate students and their instructors. It is ideal for those coming either from pure mathematics or statistics backgrounds who wish to develop their understanding of association schemes.
Download or read book Algebraic Combinatorics written by Eiichi Bannai and published by Walter de Gruyter GmbH & Co KG. This book was released on 2021-02-22 with total page 444 pages. Available in PDF, EPUB and Kindle. Book excerpt: Algebraic combinatorics is the study of combinatorial objects as an extension of the study of finite permutation groups, or, in other words, group theory without groups. In the spirit of Delsarte's theory, this book studies combinatorial objects such as graphs, codes, designs, etc. in the general framework of association schemes, providing a comprehensive overview of the theory as well as pointing out to extensions.
Download or read book Algebraic Combinatorics and the Monster Group written by Alexander A. Ivanov and published by Cambridge University Press. This book was released on 2023-08-17 with total page 584 pages. Available in PDF, EPUB and Kindle. Book excerpt: Covering, arguably, one of the most attractive and mysterious mathematical objects, the Monster group, this text strives to provide an insightful introduction and the discusses the current state of the field. The Monster group is related to many areas of mathematics, as well as physics, from number theory to string theory. This book cuts through the complex nature of the field, highlighting some of the mysteries and intricate relationships involved. Containing many meaningful examples and a manual introduction to the computer package GAP, it provides the opportunity and resources for readers to start their own calculations. Some 20 experts here share their expertise spanning this exciting field, and the resulting volume is ideal for researchers and graduate students working in Combinatorial Algebra, Group theory and related areas.
Download or read book Applications of the Askey Wilson Polynomials to Association Schemes written by Laura Mariko Chihara and published by . This book was released on 1985 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Strongly Regular Graphs written by Andries E. Brouwer and published by . This book was released on 2022-01-13 with total page 481 pages. Available in PDF, EPUB and Kindle. Book excerpt: This monograph on strongly regular graphs is an invaluable reference for anybody working in algebraic combinatorics.
Download or read book Recent Results in the Theory of Graph Spectra written by D.M. Cvetkovic and published by Elsevier. This book was released on 1988-01-01 with total page 319 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this volume is to review the results in spectral graph theory which have appeared since 1978. The problem of characterizing graphs with least eigenvalue -2 was one of the original problems of spectral graph theory. The techniques used in the investigation of this problem have continued to be useful in other contexts including forbidden subgraph techniques as well as geometric methods involving root systems. In the meantime, the particular problem giving rise to these methods has been solved almost completely. This is indicated in Chapter 1. The study of various combinatorial objects (including distance regular and distance transitive graphs, association schemes, and block designs) have made use of eigenvalue techniques, usually as a method to show the nonexistence of objects with certain parameters. The basic method is to construct a graph which contains the structure of the combinatorial object and then to use the properties of the eigenvalues of the graph. Methods of this type are given in Chapter 2. Several topics have been included in Chapter 3, including the relationships between the spectrum and automorphism group of a graph, the graph isomorphism and the graph reconstruction problem, spectra of random graphs, and the Shannon capacity problem. Some graph polynomials related to the characteristic polynomial are described in Chapter 4. These include the matching, distance, and permanental polynomials. Applications of the theory of graph spectra to Chemistry and other branches of science are described from a mathematical viewpoint in Chapter 5. The last chapter is devoted to the extension of the theory of graph spectra to infinite graphs.
Download or read book Algebraic Combinatorics written by Chris Godsil and published by Routledge. This book was released on 2017-10-19 with total page 382 pages. Available in PDF, EPUB and Kindle. Book excerpt: This graduate level text is distinguished both by the range of topics and the novelty of the material it treats--more than half of the material in it has previously only appeared in research papers. The first half of this book introduces the characteristic and matchings polynomials of a graph. It is instructive to consider these polynomials together because they have a number of properties in common. The matchings polynomial has links with a number of problems in combinatorial enumeration, particularly some of the current work on the combinatorics of orthogonal polynomials. This connection is discussed at some length, and is also in part the stimulus for the inclusion of chapters on orthogonal polynomials and formal power series. Many of the properties of orthogonal polynomials are derived from properties of characteristic polynomials. The second half of the book introduces the theory of polynomial spaces, which provide easy access to a number of important results in design theory, coding theory and the theory of association schemes. This book should be of interest to second year graduate text/reference in mathematics.
Download or read book written by and published by . This book was released on 1999 with total page 678 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Combinatorics and Graphs written by Richard A. Brualdi and published by American Mathematical Soc.. This book was released on 2010 with total page 278 pages. Available in PDF, EPUB and Kindle. Book excerpt: A collection of papers presented at the international conference IPM 20--Combinatorics 2009, which includes topics covering permutations, designs, graph minors, graph coloring, graph eigenvalues, distance regular graphs and association schemes, hypergraphs, and arrangements.
Download or read book Handbook of Combinatorics Volume 1 written by Ronald L. Graham and published by Elsevier. This book was released on 1995-12-11 with total page 1124 pages. Available in PDF, EPUB and Kindle. Book excerpt: Handbook of Combinatorics, Volume 1 focuses on basic methods, paradigms, results, issues, and trends across the broad spectrum of combinatorics. The selection first elaborates on the basic graph theory, connectivity and network flows, and matchings and extensions. Discussions focus on stable sets and claw free graphs, nonbipartite matching, multicommodity flows and disjoint paths, minimum cost circulations and flows, special proof techniques for paths and circuits, and Hamilton paths and circuits in digraphs. The manuscript then examines coloring, stable sets, and perfect graphs and embeddings and minors. The book takes a look at random graphs, hypergraphs, partially ordered sets, and matroids. Topics include geometric lattices, structural properties, linear extensions and correlation, dimension and posets of bounded degree, hypergraphs and set systems, stability, transversals, and matchings, and phase transition. The manuscript also reviews the combinatorial number theory, point lattices, convex polytopes and related complexes, and extremal problems in combinatorial geometry. The selection is a valuable reference for researchers interested in combinatorics.
Download or read book Spectra of Graphs written by Andries E. Brouwer and published by Springer Science & Business Media. This book was released on 2011-12-17 with total page 254 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book gives an elementary treatment of the basic material about graph spectra, both for ordinary, and Laplace and Seidel spectra. The text progresses systematically, by covering standard topics before presenting some new material on trees, strongly regular graphs, two-graphs, association schemes, p-ranks of configurations and similar topics. Exercises at the end of each chapter provide practice and vary from easy yet interesting applications of the treated theory, to little excursions into related topics. Tables, references at the end of the book, an author and subject index enrich the text. Spectra of Graphs is written for researchers, teachers and graduate students interested in graph spectra. The reader is assumed to be familiar with basic linear algebra and eigenvalues, although some more advanced topics in linear algebra, like the Perron-Frobenius theorem and eigenvalue interlacing are included.
Download or read book Antipodal covers written by Aleksandar Jurišić and published by . This book was released on 1995 with total page 139 pages. Available in PDF, EPUB and Kindle. Book excerpt: A connected graph $G$ is called distance-regular graph if for any two vertices $u$ and $v$ of $G$ at distance $i$, the number $c_i$ (resp. $B-i$) of neighbours of $v$ at distance $i-1$ (resp. $i+1$) from $u$ depends only on $i$ rather than on individual vertices. A distance regular graph $G$ of diameter $d \in \{2m,2m+1\}$ is antipodal ($r$-cover of its folded graph) if and only if $b_i = c_{d-i}$, for $i = 0,...,d$, $i \ne m$ (and $r = 1+b_m/c_{d-m}$). For example, the dodecahedron is a double-cover of the Petersen graph, the cube is the double-cover of the tetrahedron. Most finite objects of sufficient regularity are closed related to certain distance-regular graphs, in particular, antipodal distance-regular graphs give rise to projective planes, Hadamard matrices and other interesting combinatorial objects. Distance-regular graphs serve as an alternative approach to these objects and allow the use of graph eigenvalues, graph representations, association schemes and the theory of orthogonal polynomials. We start with cyclic covers and spreads of generalized quadrangles and find a switching which uses some known infinite families of antipodal distance-regular graphs of diameter three to produce new ones. Then we examine antipodal distance-families of antipodal distance-regular graphs of diameter three to produce new ones. Then we examine antipodal distance-regular graphs of diameter four and five. Together with J. Koolen we use representations of graphs to extend in the case of diameter four the result P. Terwilliger who has shown, using the theory of Krein modules, that in a $Q$-polynomial antipodal diatance-regular graph the neighbourhood of any vertex is a strongly regular graph. New nonexistence conditions for covers are derived from that. This study relates to the above switching and to extended generalized quadrangles. In an imprimitive association scheme there always exists a merging (i.e., a grouping of the relations) which gives a new nontrivial association scheme. We determine when merging in an antipodal distance-regular graph produces a distance-regular graphs with regular near polygons containing a spread. In case of diameter three we get a Brouwer's characterization of certain distance-regular graphs with generalized quadrangles containing a spread. Finally, antipodal covers of strongly regular graphs which are not necessarily distance-regular are studied. In most cases the structure of short cycles provides a tool to determine the existence of an antipodal cover. A relationship between antipodal covers of a graph and its line graph is investigated. Antipodal covers of complete bipartite graphs and their line graphs (lattice graphs) are characterized in terms of weak resolvable transversal designs which are, in the case of maximal covering index, equivalent to affine planes with a parallel class deleted. We conclude by mentioning two results which indicate the importance of antipodal distance-regular graphs. The first one is a joint work with M. Araya and A. Hiraki. Let $G$ be a distance-regular graph of diameter $d$ and valency $k>2$. If $b_t=1$ and $2t \le d$, then $G$ is an antipodal double-cover. Consenquently, if $m>2$ the multiplicity of an eigenvalue of the adjacency matrix of $G$ and if $G$ is not an antipodal double-cover then $d \le 2m-3$. This result is an improvement of Godsil's diameter bound and it is very important for the classification of distance-regular graphs with an eigenvalue of small multiplicity (as opposed to dual classification of distance-regular graphs with small valency). The second result is joint work with C. Godsil. We show that distance-regular graphs that contain maximal independent geodesic paths of short length are antipodal. A new infinite family of feasible parameters of antipodal distance-regular graphs of diameter four is found. As an auxiliary result we use equitable partitions to show that the determinant of a Töplitz matrix can be written as a product of two determinants of approximately half size of the original one.
Download or read book Handbook of Combinatorics Volume 1 written by Bozzano G Luisa and published by Elsevier. This book was released on 1995-12-11 with total page 1121 pages. Available in PDF, EPUB and Kindle. Book excerpt: Handbook of Combinatorics, Volume 1 focuses on basic methods, paradigms, results, issues, and trends across the broad spectrum of combinatorics. The selection first elaborates on the basic graph theory, connectivity and network flows, and matchings and extensions. Discussions focus on stable sets and claw free graphs, nonbipartite matching, multicommodity flows and disjoint paths, minimum cost circulations and flows, special proof techniques for paths and circuits, and Hamilton paths and circuits in digraphs. The manuscript then examines coloring, stable sets, and perfect graphs and embeddings and minors. The book takes a look at random graphs, hypergraphs, partially ordered sets, and matroids. Topics include geometric lattices, structural properties, linear extensions and correlation, dimension and posets of bounded degree, hypergraphs and set systems, stability, transversals, and matchings, and phase transition. The manuscript also reviews the combinatorial number theory, point lattices, convex polytopes and related complexes, and extremal problems in combinatorial geometry. The selection is a valuable reference for researchers interested in combinatorics.
