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 9/149/21

Luz DeAlba, Sign Pattern Matrices 9/28  10/05

Leslie Hogben, Minimal rank 2 graphs (paper of Barrett, van der Holst,
Loewy), 10/1211/2

Y. T. Poon, Offdiagonal 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
20022003

Kenneth R. Driessel, On Structured IsoSpectral 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 nSpace,
an exercise in classical representation theory, 11/14, 11/21

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, CohenMacaulay rings and polynomials
with real zeros, 2/20

Amy Wangsness, Combinatorial Matrix theory, 2/27, 3/6

Irvin Hentzel, The LhuilierLemoine point, the Fermat point, and other
constructions. 3/13

Kenneth R. Driessel, Some algebraic questions concerning eigenproblems.
3/27

Leslie Hogben, Relationships between the completion problems for
various classes of matrices. 4/17
20012002

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 P0Matrices 9/2710/11

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 ChiKwong Li, College of William and Mary, Numerical Ranges and
Dilations (colloquium)11/6

Bryan Cain, Hermitians whose product is normal. 11/15

Leslie Hogben, Nonnegative matrices and their digraphs 11/29

Leslie Hogben, The Matrix Completion Problems for Related Pairs of Subclasses
of P and P0Matrices 12/6

Jim Murdock, Matrix perturbation theory via normal, hypernormal, and metanormal
forms 12/13

Irvin Hentzel, The Quaternions and the group of finite (3dimensional)
rotations 1/24/02

Yiu Tung Poon, Completion problems on the unitary orbit of a Hermitian
matrix. 1/312/7

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 nary 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

JiYoung Choi Report from International Conference
in Combinatorial Matrix Theory , Pohang, S. Korea 3/14

Mike Shedenhelm, The nonnegative P0matrix Completion Problem 3/28

Benard Kivunge, The nonnegative P0matrix Completion Problem 4/44/11

Ji Young Choi, MultiRestricted Numbers, 4/18

Sandy Nordstrom,The Nonnegative P0Matrix Completion Problem: Classification
of Patterns for 4 x 4 Matrices 4/25
20002001

Luz DeAlba, Effect of perturbation
on the PerronFrobenius eigenvalue of a nonnegative matrix using polynomials
9/14/00

Jim Murdock Algorithms for splitting a matrix into
nilpotent and semisimple parts 9/2128/00

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 0Matrix 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 MMatrix 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 P0Matrix Completion Problem 3/01

Mandi Maxwell, The P0Matrix Completion Problem 4/01

Ji Young Choi, The P0Matrix Completion Problem 4/01

Amy Wangsness, The P0Matrix Completion Problem 4/01
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