Polynomial automorphisms of a generalized extraspecial ℚ-group and its extension.

Let G be the direct product of a generalized extraspecial ℚ -group and finitely many copies of ℚ π , where π is a set of primes. It is proved that every polynomial automorphism of G is an inner automorphism. As an application of this result, the structure of the group generated by all polynomial automorphisms of an extension of ℚ by a direct sum of finitely many copies of ℚ is determined. [ABSTRACT FROM AUTHOR]