منابع مشابه
Isotopy problems for saddle surfaces
Four mutually dependent facts are proven. • A smooth saddle sphere in S has at least four inflection arches. • Each hyperbolic hérisson H generates an arrangement of disjoint oriented great semicircles on the unit sphere S. On the one hand, the semicircles correspond to the horns of the hérisson. On the other hand, they correspond to the inflection arches of the graph of the support function hH...
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We investigate the following problem: Given two embeddings G1 and G2 of the same abstract graph G on an orientable surface S, decide whether G1 and G2 are isotopic; in other words, whether there exists a continuous family of embeddings between G1 and G2. We provide efficient algorithms to solve this problem in two models. In the first model, the input consists of the arrangement of G1 (resp., G...
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The flame forming process is widely used to manufacture ship hull plates. The saddle-shaped surfaces have different curvatures in perpendicular angles of planes and the manufacturers face an anti-clastic curvature. In this article, the manufacturing of saddle-shaped surfaces utilizing the flame forming process is investigated. The spiral irradiating scheme is used for forming. In order to study...
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This paper investigates dynamics that persist under isotopy in classes of orientation-preserving homeomorphisms of orientable surfaces. The persistence of periodic points with respect to periodic and strong Nielsen equivalence is studied. The existence of a dynamically minimal representative with respect to these relations is proved and necessary and sufficient conditions for the isotopy stabil...
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In this note, we discuss the mean curvature flow of graphs of maps between Riemannian manifolds. Special emphasis will be placed on estimates of the flow as a non-linear parabolic system of differential equations. Several global existence theorems and applications to isotopy problems in geometry and topology will be presented. The results are based on joint works of the author with his collabor...
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ژورنال
عنوان ژورنال: European Journal of Combinatorics
سال: 2010
ISSN: 0195-6698
DOI: 10.1016/j.ejc.2009.10.002