27 research outputs found
A Helson-Szeg\"o theorem for subdiagonal subalgebras with applications to Toeplitz operators
We formulate and establish a noncommutative version of the well known
Helson-Szego theorem about the angle between past and future for subdiagonal
subalgebras. We then proceed to use this theorem to characterise the symbols of
invertible Toeplitz operators on the noncommutative Hardy spaces associated to
subdiagonal subalgebras