Let $R$ be a Noetherian local ring. We prove that is regular of dimension at most four if, and only every prime ideal, defining Gorenstein quotient ring, syzygetic. deduce characterization these rings in terms the Andr\'e-Quillen homology.

Introduction APIARY [23~, and subsequently GORENSTEIN Eg] and SAMUEL [2(r proved 9 3-~ t that if (2 is a point on a plane curve then no=2d Q, where dQ=dlmw0/ 9 Q and nQ = dim C'Q/~Q, 9 being the local ring of Q, CQ its normalization, and ~Q the conductor. This condition has received attention from a variety of algebraic geometers, and recently ROQUETTE [19J and BEI~GER [52 have put it i n a rat...

We characterize all Gorenstein rings generated by strongly stable sets of monomials degree two. compute their Hilbert series in several cases, which also provides an answer to a question Migliore and Nagel.