7 citations · 10 across the 3 of their papers we have counts for
4 papers
A mini-max problem for self-adjoint Toeplitz matrices
Dennis Courtney, Donald Sarason
We study a minimum problem and associated maximum problem for finite, complex, self-adjoint Toeplitz matrices. If is such a matrix, of size -by-, we identify …
Composition Operators and Endomorphisms
Dennis Courtney, Paul S. Muhly, Samuel W. Schmidt
If is an inner function, then composition with induces an endomorphism, , of that leaves invariant. We investigate the stru…
Unions of arcs from Fourier partial sums
Dennis Courtney
Elementary complex analysis and Hilbert space methods show that a union of at most n arcs on the circle is uniquely determined by the nth Fourier partial sum of its characteristic…
Lifting endomorphisms to automorphisms
William Arveson, Dennis Courtney
Normal endomorphisms of von Neumann algebras need not be extendable to automorphisms of a larger von Neumann algebra, but they always have asymptotic lifts. We describe the structu…