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On a new criterion for isomorphism of Artinian Gorenstein algebras

2012/01/30 by Isaev, A. V.
#13H10 #Commutative Algebra (math.AC) #FOS: Mathematics

paper · doi:10.48550/arxiv.1201.6100

Abstract

To every Gorenstein algebra A of finite vector space dimension greater than 1 over a field \FF of characteristic zero, and a linear projection π on its maximal ideal \mathfrak m with range equal to the annihilator \Ann(\mathfrak m) of \mathfrak m, one can associate a certain algebraic hypersurface Sπ⊂\mathfrak m, which is the graph of a polynomial map Pπ:kerπ\ra\Ann(\mathfrak m)≃\FF. Recently, in \rm\citeFIKK, \rm\citeFK the following surprising criterion was obtained: two Gorenstein algebras A, A are isomorphic if and only if any two hypersurfaces Sπ and Sπ arising from A and A, respectively, are affinely equivalent. The proof is indirect and relies on a CR-geometric argument. In the present paper we give a short algebraic proof of this statement. We also compare the polynomials Pπ with Macaulay's inverse systems. Namely, we show that the restrictions of Pπ to certain subspaces of kerπ are inverse systems for A.

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