منابع مشابه
Singularities of Generalized Richardson Varieties
Richardson varieties play an important role in intersection theory and in the geometric interpretation of the Littlewood-Richardson Rule for flag varieties. We discuss three natural generalizations of Richardson varieties which we call projection varieties, intersection varieties, and rank varieties. In many ways, these varieties are more fundamental than Richardson varieties and are more easil...
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A family of caps constructed by Ebert, Metsch and T. Szönyi [8] results from projecting a Veronesian or a Grassmannian to a suitable lower-dimensional space. We improve on this construction by projecting to a space of much smaller dimension. More precisely we partition PG(3r − 1, q) into a (2r − 1)−space, an (r − 1)−space and qr − 1 cyclic caps, each of size (q2r − 1)(q − 1). We also decide whe...
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We characterize pointed varieties of universal algebras in which (A × B)/A ≈ B, i.e. all product projections are normal epimorphisms. 1. Definition. We will say that a pointed category C has normal projections if every product projection A × B → B in C is a normal epimorphism. Equivalently, for any two objects A and B in such a category C, forming the product A×B and then factoring it by A ≈ A×...
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Let IM and IN be defining ideals of toric varieties such that IM is a projection of IN , i.e. IN ⊆ IM . We give necessary and sufficient conditions for the equality IM = rad(IN + (f1, . . . , fs)), where f1, . . . , fs belong to IM . Also a method for finding toric varieties which are set-theoretic complete intersection is given. Finally we apply our method in the computation of the arithmetica...
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ژورنال
عنوان ژورنال: Journal für die reine und angewandte Mathematik (Crelles Journal)
سال: 2014
ISSN: 0075-4102,1435-5345
DOI: 10.1515/crelle-2012-0045