منابع مشابه
Small Covers over Prisms
In this paper we calculate the number of equivariant diffeomorphism classes of small covers over a prism.
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In the present paper we find a bijection between the set of small covers over an n-cube and the set of acyclic digraphs with n labeled nodes. Using this, we give a formula of the number of small covers over an n-cube (generally, a product of simplices) up to Davis-Januszkiewicz equivalence classes and Zn2 -equivariant diffeomorphism classes. Moreover we prove that the number of acyclic digraphs...
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Let S be any family of n c-oriented polygons of the two-dimensional Euclidean plane E, i.e., bounded intersection of halfplanes whose normal directions of edges belong to a .xed collection of c distinct directions. Let (S) denote the packing number of S, that is the maximum number of pairwise disjoint objects of S. Let (S) be the transversal number of S, that is the minimum number of points req...
متن کاملThe Number of Orientable Small Covers over Cubes
In the present paper, we count orientable small covers over cubes. We also prove that the ratio of orientable small covers to all things approaches to 0 as n increases.
متن کاملSmall deformations of polygons
We describe the first-order variations of the angles of Euclidean, spherical or hyperbolic polygons under infinitesimal deformations such that the lengths of the edges do not change. Using this description, we introduce a vector-valued quadratic invariant b on the space of those isometric deformations which, for convex polygons, has a remarkable positivity property. We give two geometric applic...
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ژورنال
عنوان ژورنال: Journal of the Mathematical Society of Japan
سال: 2019
ISSN: 0025-5645
DOI: 10.2969/jmsj/79727972