ISU Linear Algebra Seminar

In Spring 2005 the Linear Algebra Seminar combined with the Discrete Math/Theory of Conmputing Seminar to for the Discrete Math Seminar

This page contain information on the Linear Algebra Seminar from prior semesters.

The Linear Algebra Seminar at Iowa State University is an eclectic mix of topics, all related to matrices or linear operators.
Presentations vary with the speaker and include the speaker's research, related research by others, and expository talks. If the
semester has a theme, approximately half the talks during the semester relate to the theme.

Past Lectures

Fall 2004

Leslie Hogben, Report from BIRS Workshop Directions in Combinatorial Matrix Theory 9/14-9/21
Luz DeAlba, Sign Pattern Matrices 9/28 - 10/05
Leslie Hogben, Minimal rank 2 graphs (paper of Barrett, van der Holst, Loewy), 10/12-11/2
Y. T. Poon, Off-diagonal block of a unitary orbit, 11/9 - 11/16
Amy Wangsness, Matrix Completion Problems for Various Classes fo P_0,1 Matrices. 11/30
Bryan Shader, University of Wyoming, The minimum number of distinct eigenvalues among the symmetricmatrices with a given graph (colloquium), 12/7 Abstract

Spring 2004 Theme: Spectral Graph Theory/Inverse Eigenvalue Problem of a Graph

The graph G(A) of a real symmetric matrix A has vertices {1,...,n}, and as edges the unordered pairs {i,j} such that a_{i j} is nonzero (with distinct i, j). In recent years there has been a great deal of interest in the possible eigenvalues of a real symmetric matrix whose nonzero entries are described by a given graph, especially a tree (i.e., a connected graph with no cycles). The question of possible eigenvalues is referred to as the Inverse Eigenvalue Problem. Many of the talks this semester will focus on the Inverse Eigenvalue Problem and related concepts. Additional talks will explore other aspects of spectral graph theory including the spectra of various matrices associated with a graph.

Leslie Hogben, Introduction to Spectral Graph Theory and the Inverse Eigenvalue Problem, 1/15
Leslie Hogben, Path Cover Number, Maximal Multiplicity, and Minimal Rank for Graphs I, II 1/22, 1/29
Leslie Hogben, Possible Ordered Multiplicity Lists of a Tree 2/5
Leslie Hogben, Ordered Multiplicity Lists and the Inverse Eigenvalue Problem of a Graph 2/12
Luz DeAlba, Sign Pattern Matrices, 2/19, 2/26
Amy Wangsness, Sign Symmetrix P0,1 matrix Completion Problem, 3/25, 4/1
Leslie Hogben, Spectral Graph Theory, 4/8, 4/15, 4/22

2002-2003

Kenneth R. Driessel, On Structured Iso-Spectral Surfaces 9/19,9/26
Leslie Hogben, Minimal rank and maximal eigenvalue multiplicity of symmetric matrices with a given graph 10/3, 10/10
Yiu Tung Poon, Sum of Hermitian matrices and related areas, 10/17, 10/24
Leslie Hogben, Maximal Multiplicity of an Eigenvalue of a Matrix whose Graph is a Tree, 10/31, 11/7
Christian Roettger, Where Are They? or The distribution of Normal Integral Bases in n-Space,

Tim Hardy, William Penn University, Generalized Distance Matrices and Interpolation, 12/5, 12/12.
Leslie Hogben, Relationships between Completion Problems for the classes weakly sign symmetric P0-, sign symmetric P0-, weakly sign symmetric P- and sign symmetric P- matrices, 1/23, 1/30
Joe Keller, Algebra of Relativistic Velocity Addition & Thomas Rotation, 2/13
Mark Skandera, University of Michigan, Cohen-Macaulay rings and polynomials with real zeros, 2/20
Amy Wangsness, Combinatorial Matrix theory, 2/27, 3/6
Irvin Hentzel, The Lhuilier-Lemoine point, the Fermat point, and other constructions. 3/13
Kenneth R. Driessel, Some algebraic questions concerning eigen-problems. 3/27
Leslie Hogben, Relationships between the completion problems for various classes of matrices. 4/17

2001-2002

Bryan Cain, Group homomorphisms hi such that h1(x1)+...+hn(x n)=y is solvable.9/7
Leslie Hogben, Positivity Classes of Normal Matrices 9/14
Y. T. Poon, Convexity and matrix completion problems on the unitary orbit of a hermitian matrix. 9/21
Leslie Hogben, The Matrix Completion Problems for Related Pairs of Subclasses of P- and P0-Matrices 9/27-10/11
Bryan Cain, Diagonal Stability 10/18
Y. T. Poon, Convexity and matrix completion problems on the unitary orbit of a hermitian matrix. 10/25, 11/1, 11/8
Professor Chi-Kwong Li, College of William and Mary, Numerical Ranges and Dilations (colloquium)11/6
Bryan Cain, Hermitians whose product is normal. 11/15
Leslie Hogben, Non-negative matrices and their digraphs 11/29
Leslie Hogben, The Matrix Completion Problems for Related Pairs of Subclasses of P- and P0-Matrices 12/6
Jim Murdock, Matrix perturbation theory via normal, hypernormal, and metanormal forms 12/13
Irvin Hentzel, The Quaternions and the group of finite (3-dimensional) rotations 1/24/02
Yiu Tung Poon, Completion problems on the unitary orbit of a Hermitian matrix. 1/31-2/7
Leslie Hogben, Report on Graph Spectra (from International Conference in Combinatorial Matrix Theory , Pohang, S. Korea) 2/14
Murray Bremner, University of Saskatchewan, Classification of n-ary operations using the group ring of the symmetric group, 2/21
Leslie Hogben, Possible Multiplicities of Eigenvalues of a Symmetric Matrix with a given Graph (from International Conference in Combinatorial Matrix Theory , Pohang, S. Korea) 2/28
Ji-Young Choi Report from International Conference in Combinatorial Matrix Theory , Pohang, S. Korea 3/14
Mike Shedenhelm, The nonnegative P0-matrix Completion Problem 3/28
Benard Kivunge, The nonnegative P0-matrix Completion Problem 4/4-4/11
Ji Young Choi, Multi-Restricted Numbers, 4/18
Sandy Nordstrom,The Nonnegative P0-Matrix Completion Problem: Classification of Patterns for 4 x 4 Matrices 4/25

2000-2001

Luz DeAlba, Effect of perturbation on the Perron-Frobenius eigenvalue of a non-negative matrix using polynomials 9/14/00
Jim Murdock- Algorithms for splitting a matrix into nilpotent and semisimple parts 9/21-28/00
Irvin Hentzel- Calculus problem. 10/5/00
Leslie Hogben- Symmetric Matrix Completion Problems I: 10/12/00
Leslie Hogben, Symmetric Matrix Completion Problems II: 10/19/00
Maria Axenovich- Prohibited submatrices of Special Type in Binary Matrices and Integral Matrices. 10/26/00
Leslie Hogben- Report on SIAM Applied Linear Algebra Conference in Raleigh 1: Two reports: Richard Varga's Gershgorin Disks and Cassini Ovals. Brenda Kroschel's Totally Nonnegative Matrix Completion Problem. 11/00 Photos
Leslie Hogben- The Relationship between the P and P 0-Matrix Completion Problems 11/00
Leslie Hogben- Report 2 on SIAM Applied Linear Algebra Conference in Raleigh 2: Jim Weaver's Tournament matrices and Olga Holtz' Not all GKK Tau matrices are stable. 11/00 Photos
Irvin Hentzel- A hemisphere floats flat side up or round side up. Which is preferred? 12/00
Leslie Hogben- The Singular Inverse M-Matrix Completion Problem 12/00
Charles R. Johnson, College of William and Mary- Possible Lists of Multiplicities for the Eigenvalues of Hermitian Matrices with a Given Graph. 1/01
Y. T. Poon- Spectral inequalities and equalities involving products of matrices 1/01
Leslie Hogben, Another Perspective on Matrix Completions 2/01
Irvin Hentzel- The Cayley Doubling Process. 2/01
Leslie Hogben- Cycle Completability 3/01
Amy Wangsness, The P0-Matrix Completion Problem 3/01
Mandi Maxwell, The P0-Matrix Completion Problem 4/01
Ji Young Choi, The P0-Matrix Completion Problem 4/01
Amy Wangsness, The P0-Matrix Completion Problem 4/01

Linear Algebra Sites


Leslie Hogben's Home Page Mathematics Department Home Page			13-Dec-04