M. Shirvani et Jz. Goncalves, FREE GROUP-ALGEBRAS IN THE FIELD OF FRACTIONS OF DIFFERENTIAL POLYNOMIAL-RINGS AND ENVELOPING-ALGEBRAS, Journal of algebra (Print), 204(2), 1998, pp. 372-385
We construct free group algebras in the quotient ring of the different
ial polynomial ring K[X; delta], for suitable division rings K and non
zero derivations delta in K. (C) 1998 Academic Press.