Let A be a noetherian local commutative ring and let M be a suitable complex
of A-modules. This paper proves that M is a dualizing complex for A if and only
if the trivial extension A \ltimes M is a Gorenstein Differential Graded
Algebra. As a corollary follows that A has a dualizing complex if and only if
it is a quotient of a Gorenstein local Differential Graded Algebra.Comment: 9 pages. To appear in Fundamenta Mathematica