Cowen, Carl C.Gallardo-Gutiérrez, Eva A.2019-03-072019-03-072017Cowen, Carl & Gallardo-Gutierrez, Eva. (2017). A new proof of a Nordgren, Rosenthal and Wintrobe Theorem on universal operators. In F. Botelho, R. King, and T. S. S. R. K. Rao (Eds.) Problems and Recent Methods in Operator Theory (687, pp 97-102). American Mathematical Society. http://dx.doi.org/10.1090/conm/687/13727https://hdl.handle.net/1805/18546A striking result by Nordgren, Rosenthal and Wintrobe states that the Invariant Subspace Problem is equivalent to the fact that any minimal invariant subspace for a composition operator Cφ induced by a hyperbolic automorphism φ of the unit disc D acting on the classical Hardy space H² is one dimensional. We provide a completely different proof of Nordgren, Rosenthal and Wintrobe’s Theorem based on analytic Toeplitz operators.enuniversal operatorsNordgren, Rosenthal and Wintrobe's TheoremproofBook chapter