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HEINZ BAUSCHKE, University of Guelph
Asymptotic behaviour of the composition of two resolvents
Consider
the problem of finding a point in the intersection of two nonempty closed
convex sets in a Hilbert space. The method of alternating projections is an
iterative attempt to solve this problem. If the intersection of the two
sets is nonempty, then-this is a classical result due to Bregman-the
sequence generated converges weakly to a common point; otherwise, the
sequence either tends to infinity in norm or it possesses two cluster
points realizing the gap between the two sets.
In this
talk, I will discuss recent extensions of this result concerning the
asymptotic behaviour of resolvents and Bregman proximal maps.
(Based on
joint work with Patrick Combettes (Paris 6),
Dominikus Noll (Toulouse),
and Simeon Reich (Technion).)
GRAHAME BENNETT, Indiana
University, Bloomington, Indiana
Summability for those without
We
consider several attractive and easy-to-state problems. These have no
apparent connection with Summability Theory, yet their solutions are all
centered upon one of David Borwein's favorite topics: Hausdorff matrices.
PETER
BORWEIN, Simon Fraser University
Three Highly Computational Problems in Number Theory
A number of classical and not so classical problems in number theory concern finding polynomials with integer coefficients that are small in some norm. These include old
chestnuts like the Merit Factor Problem of Golay, Lehmer's Conjecture and Littlewood's (other)
Conjecture.
PETER
CASS,
University of Western Ontario
(and JONATHAN BORWEIN, Dalhousie),
A Retrospective on David Borwein's
Contribution to Mathematical Research and David and Me
(a 1971 ms)
MICHAEL
OVERTON, Courant Institute of Mathematical Sciences, NYU
Optimal Stability and Eigenvalue Multiplicity
We
consider the problem of minimizing over an affine set of square matrices
the maximum of the real parts of the eigenvalues. Such problems are
prototypical in robust control and stability analysis. Under nondegeneracy
conditions, we show that the multiplicities of the active eigenvalues at a
critical matrix remain unchanged under small perturbations of the problem.
Furthermore, each distinct active eigenvalue corresponds to a single Jordan
block. This behavior is crucial for optimality conditions and numerical
methods. Our techniques blend nonsmooth optimization and matrix analysis.
(This is joint work with James V. Burke (U. Wash.) and Adrian
S. Lewis (SFU).)
BRUCE
SHAWYER, Memorial University
of Newfoundland
A Tribute and A Plethora of Remarkable Concurrences
This talk is in two
parts:
1. An appreciation of David Borwein as a colleague,
problem solver, supervisor and person.
2. A Plethora of Remarkable Concurrences, dedicated
to David Borwein on his 80th birthday.
There are several
examples of concurrence in classical triangle geometry. For example, the
medians, the altitudes, the angle bisectors and the perpendicular bisectors
of the sides.
Here we show that
there is a plethora of concurrences with some remarkable properties.
BRUCE WATSON, Memorial University
of Newfoundland
Discrete Power Series Methods
In 1989 and 1990
papers, Maddox and Armitage discretized the well-known Cesàro and Abel
methods. The author extends the definitions to discrete power series and
weighted mean methods and gives some abelian and tauberian results.
JIM
ZHU, Western Michigan University,
Kalamazoo.
A variational proof of Birkhoff's theorem on doubly
stochastic matrices
I will give a short and self-contained variational proof of Birkhoff's
theorem asserting that the extreme points of the convex set of doubly
stochastic matrices are the permutation matrices.
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