Monodromy of projections of hypersurfaces

被引:0
作者
Maria Gioia Cifani
Alice Cuzzucoli
Riccardo Moschetti
机构
[1] University of Pavia,Department of Mathematics ’F. Casorati’
[2] University of Warwick,Department of Mathematics
来源
Annali di Matematica Pura ed Applicata (1923 -) | 2022年 / 201卷
关键词
Monodromy; Projections; Uniform points; Focal points; Filling families; 14H30; 14H50; 14J10; 14J70;
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摘要
Let X be an irreducible, reduced complex projective hypersurface of degree d. A point P not contained in X is called uniform if the monodromy group of the projection of X from P is isomorphic to the symmetric group Sd\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$S_d$$\end{document}. We prove that the locus of non-uniform points is finite when X is smooth or a general projection of a smooth variety. In general, it is contained in a finite union of linear spaces of codimension at least 2, except possibly for a special class of hypersurfaces with singular locus linear in codimension 1. Moreover, we generalise a result of Fukasawa and Takahashi on the finiteness of Galois points.
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页码:637 / 654
页数:17
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