Threefolds in P5 with one apparent quadruple point

被引：13
作者：
De Poi, P [1 ]
机构：
[1] Univ Trieste, Dipartimento Sci Matemat, I-34127 Trieste, Italy
来源：
COMMUNICATIONS IN ALGEBRA | 2003年 / 31卷 / 04期
关键词：
algebraic geometry; threefolds; focal loci; congruences;
D O I：
10.1081/AGB-120018514
中图分类号：
O1 [数学];
学科分类号：
0701 ; 070101 ;
摘要：
In this article we classify all the smooth threefolds in P-5 with an apparent quadruple point provided that the family of its 4-secant lines is an irreducible (first order) congruence. This is sufficient to conclude the classification of all the smooth codimension two varieties in P-n with one apparent (n - 1)-point and with irreducible family of (n - 1)-secant lines.
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页码：1927 / 1947
页数：21
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