Automorphy character of an orbit Blaschke product
ID: automorphy-character-of-an-orbit-blaschke-product
Let a group of Möbius transformations of the unit disk have an orbit satisfying the Blaschke condition, counted once per distinct orbit point. For its Blaschke product , invariance of the pseudohyperbolic distance and permutation of the orbit give . The ratio extends across its zeros and has modulus one, so the open mapping theorem makes it a constant . Composition gives a group homomorphism . It is essential to compare moduli of the products: two arbitrary bounded holomorphic functions with identical zeros need not have constant quotient.
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