ABSTRACT
Let dA denote the Lebesgue measure on the open unit disk https://www.w3.org/1998/Math/MathML"> D https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781351045551/0d0c2edd-5761-460a-bbe7-0d763d2f484f/content/eq3078.tif" xmlns:xlink="https://www.w3.org/1999/xlink"/> in the complex plane ℂ, normalized so that the measure of the disk https://www.w3.org/1998/Math/MathML"> D https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781351045551/0d0c2edd-5761-460a-bbe7-0d763d2f484f/content/eq3079.tif" xmlns:xlink="https://www.w3.org/1999/xlink"/> is 1. The complex space L 2( https://www.w3.org/1998/Math/MathML"> D https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781351045551/0d0c2edd-5761-460a-bbe7-0d763d2f484f/content/eq3080.tif" xmlns:xlink="https://www.w3.org/1999/xlink"/> , dA) is a Hilbert space with the inner product https://www.w3.org/1998/Math/MathML"> 〈 f , g 〉 = ∫ D f ( z ) g ( z ) ¯ d A ( z ) . https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781351045551/0d0c2edd-5761-460a-bbe7-0d763d2f484f/content/eq3081.tif" xmlns:xlink="https://www.w3.org/1999/xlink"/>
