Projective Schemes with Degenerate General Hyperplane Section II
نویسنده
چکیده
We study projective non-degenerate closed subschemes X ⊆ P having degenerate general hyperplane section, continuing our earlier work. We find inequalities involving three relevant integers, namely: the dimensions of the spans of Xred and of the general hyperplane section of X, and a measure of the “fatness” of X, which is introduced in this paper. We prove our results first for curves and then for higher dimensional schemes by induction, via hyperplane sections. All our proofs and results are characteristic free. We add also many clarifying examples. MSC 2000: 14H50, 14N05 (primary); 14M99 (secondary)
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