EXTENSIONS OF α-REFLEXIVE RINGS
We introduce the notion of an α-reflexive ring to extend the concept of a reflexive ring and that of an α-rigid ring. We first consider some basic properties of α-reflexive rings, including some examples needed in the process. We prove that a ring R is α-rigid if and only if R is a reduced α-reflexive ring with α a monomorphism. We next investigate the α-reflexivity of some kinds of polynomial rings. It is shown that if R is a reduced α-reflexive ring with α(1) = 1, then R[x]/(xn) is an α-reflexive ring, where (xn) is the ideal generated by xn. Moreover, for an Armendariz ring R, we prove that R is α-reflexive if and only if R[x] is α-reflexive if and only if R[x; x-1] is α-reflexive. As a sequence, some known results relating to reflexive rings are obtained as corollaries of these results.