A Helson-Szego theorem for subdiagonal subalgebras with applications to Toeplitz operators

作者：Labuschagne, Louis E.; Xu, Quanhua^*

来源：Journal of Functional Analysis, 2013, 265(4): 545-561.

DOI：10.1016/j.jfa.2013.05.015

• Helson-Szego theorem
• Angle between past and future
• Invertibility of Toeplitz operators
• Subdiagonal algebras
• Hardy spaces
• Outer operators
• Riesz-Szego factorisation

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.

• 出版日期2013-8-15
• 单位武汉大学