Threefolds of P^5 with one apparent quadruple point

Abstract

In this article we classify all the smooth threefolds of 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 of P^n with one apparent (n-1)-point and with irreducible family of (n-1)-secant lines.

AMS-LaTeX2e, 14 pages

Cited by in corpus (2)

• On first order Congruences of Lines in ${\mathbb{P}}^4$ with irreducible fundamental Surface
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