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.

引用

页码：1927 / 1947

页数：21