Prime affine algebras of GK dimension two which are almost PI algebras

Abstract

An almost PI algebra is a generalisation of a just infinite algebra which does not satisfy a polynomial identity. An almost PI algebra has some nice properties: It is prime, has a countable cofinal subset of ideals and when satisfying ACC(semiprimes), it has only countably many height 1 primes. Consider an affine prime Goldie non-simple non-PI $k$-algebra $R$ of GK dimension $<3$, where $k$ is an uncountable field. $R$ is an almost PI algebra. We give some possible additional conditions which make such an algebra primitive. This gives a partial answer to Small's question: Let $R$ be an affine prime Noetherian $k$-algebra of GK dimension 2, where $k$ is any field. Does it follow that $R$ is PI or primitive? We also show that the center of $R$ is a finite dimensional field extension of $k$, and if, in addition, $k$ is algebraically closed, then $R$ is stably almost PI.