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On tangential deformations of homogeneous polynomials
Author(s) -
Wang Zhenjian
Publication year - 2017
Publication title -
mathematische nachrichten
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.913
H-Index - 50
eISSN - 1522-2616
pISSN - 0025-584X
DOI - 10.1002/mana.201600531
Subject(s) - hypersurface , mathematics , pure mathematics , projective space , gravitational singularity , dimension (graph theory) , jacobian matrix and determinant , homogeneous polynomial , projective test , infinitesimal , homogeneous , divisor (algebraic geometry) , polynomial , ideal (ethics) , linear system , mathematical analysis , combinatorics , matrix polynomial , philosophy , epistemology
The Jacobian ideal provides the set of infinitesimally trivial deformations for a homogeneous polynomial, or for the corresponding complex projective hypersurface. In this article, we investigate whether the associated linear deformation is indeed trivial, and show that the answer is no in a general situation. We also give a characterization of tangentially smoothable hypersurfaces with isolated singularities. Our results have applications in the local study of variations of projective hypersurfaces, complementing the global versions given by J. Carlson and P. Griffiths, R. Donagi and the author, and in the study of isotrivial linear systems on the projective space, showing that a general divisor does not belong to an isotrivial linear system of positive dimension.