Skew derivations on generalized Weyl algebras

A wide class of skew derivations on degree-one generalized Weyl algebras R(a, phi) over a ring R is constructed. All these derivations are twisted by a degree-counting extensions of automorphisms of R. It is determined which of the constructed derivations are Q-skew derivations. The compatibility of these skew derivations with the natural Z-grading of R(a, phi) is studied. Additional classes of skew derivations are constructed for generalized Weyl algebras given by an automorphism phi of a finite order. Conditions that the central element a that forms part of the structure of R(a, phi) needs to satisfy for the orthogonality of pairs of aforementioned skew derivations are derived. In addition local nilpotency of constructed derivetions is studied. General constructions are illustrated by description of all skew derivations (twisted by a degree-counting extension of the identity automorphism) of generalized Weyl algebras over the polynomial ring in one variable and with a linear polynomial as the central element. (C) 2017 Elsevier Inc. All rights reserved.