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Nets of conics and associated Artinian algebras of length 7. Translation and update of the 1977 version by J. Emsalem and A. Iarrobino. (English) Zbl 1511.14014

The present paper is devoted to nets of conics and associated Artinian algebras of length \(7\) and it constitutes a translation and an update of the typescript written by Emsalem and Iarrobino in 1977. In the first part of the paper the authors classify the orbits of nets of conics under the action of the projective linear group and they determine the specialisations of these orbits by using geometric and algebraic methods. Then the authors show that Artinian algebras of the Hilbert function \(H=(1,3,3,0)\) determined by nets can be smoothed, i.e. deformed to a direct sum of fields, and that algebras of the Hilbert function \(H=(1,r,2,0)\) determined by pencils of quadrics can also be smoothed.
As a reader, I can strongly recommend this paper both as a source of useful references and as a source devoted to the classification of nets of conics (which is difficult to find in one piece in the literature).

MSC:

14C21 Pencils, nets, webs in algebraic geometry
14-02 Research exposition (monographs, survey articles) pertaining to algebraic geometry
13E10 Commutative Artinian rings and modules, finite-dimensional algebras
Full Text: DOI

References:

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