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Geometric properties of the double-point divisor

Author: Bo Ilic
Journal: Trans. Amer. Math. Soc. 350 (1998), 1643-1661
MSC (1991): Primary 14N05, 14C20, 14J40
MathSciNet review: 1422899
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Abstract: The locus of double points obtained by projecting a variety $X^{n} \subset \mathbf P^N$ to a hypersurface in $\mathbf{P}^{n+1}$ moves in a linear system which is shown to be ample if and only if $X$ is not an isomorphic projection of a Roth variety. Such Roth varieties are shown to exist, and some of their geometric properties are determined.

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Additional Information

Bo Ilic
Affiliation: Department of Mathematics, Columbia University, New York, New York 10027
Address at time of publication: Department of Mathematics, University of California, Los Angeles, California 90024

Keywords: Double-point divisor, Roth variety, Castelnuovo variety, secant variety, conductor, projection
Received by editor(s): July 20, 1996
Article copyright: © Copyright 1998 American Mathematical Society

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