Some automorphism invariance properties for multicontractions Chafiq BenhidaDan Timotin 47A1347A45multicontractionPoisson kernelcharacteristic functionautomorphism In the theory of row contractions on a Hilbert space, as initiated by Popescu, two important objects are the Poisson kernel and the characteristic function. We determine their behaviour with respect to the action of the group of unitarily implemented automorphisms of the algebra generated by creation operators on the Fock space. The case of noncommutative varieties, introduced recently by Popescu, is also discussed. Indiana University Mathematics Journal 2007 text pdf 10.1512/iumj.2007.56.3078 10.1512/iumj.2007.56.3078 en Indiana Univ. Math. J. 56 (2007) 481 - 500 state-of-the-art mathematics http://iumj.org/access/