共查询到20条相似文献,搜索用时 0 毫秒
1.
Taizo Kanenobu 《Mathematische Annalen》1981,256(4):449-452
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James F. Davis 《Mathematische Annalen》1995,301(1):507-518
Partially supported by NSF grant DMS-9208052 and the MSRI NSF grant DMS-9022140. The author held an MSRI Research Professorship while the paper was being written 相似文献
3.
James F. Davis 《Mathematische Annalen》1995,301(1):519-528
Partially supported by NSF grant DMS-9208052 and the MSRI NSF grant DMS-9022140. The author held an MSRI Research Professorship while the paper was being written 相似文献
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I. Shimada 《Commentarii Mathematici Helvetici》2003,78(2):335-362
Let be a dominant morphism, where E and B are smooth irreducible complex quasi-projective varieties. Suppose that the general fiber of $f$ is connected. We present an algebro-geometric condition under which the boundary homomorphism is well-defined, and makes the sequence exact. As an application, we calculate the fundamental group of the complement to the dual hypersurface of a smooth projective
curve.
Received: October 3, 2001 相似文献
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V. A. Koshcheev 《Proceedings of the Steklov Institute of Mathematics》2009,264(1):155-167
Efficient versions of the Cauchy criterion for the convergence in L p of greedy approximants of trigonometric Fourier series are discussed. 相似文献
8.
V. A. Koshcheev 《Proceedings of the Steklov Institute of Mathematics》2009,266(Z1):155-161
The fundamental groups π
1(Ω
n
) of the spaces Ω
n
of generalized perfect splines are calculated. For n ≥ 2, the groups are trivial; π
1(Ω1) is a free group with three generators. 相似文献
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Benjamin Steinberg 《Semigroup Forum》2010,81(1):217-227
We associate a 2-complex to the following data: a presentation of a semigroup S and a transitive action of S on a set V by partial transformations. The automorphism group of the action acts properly discontinuously on this 2-complex. A sufficient
condition is given for the 2-complex to be simply connected. As a consequence we obtain simple topological proofs of results
on presentations of Schützenberger groups. We also give a geometric proof that a finitely generated regular semigroup with
finitely many idempotents has polynomial growth if and only if all its maximal subgroups are virtually nilpotent. 相似文献
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Robert Myers 《Proceedings of the American Mathematical Society》2000,128(5):1507-1513
In this paper it is proven that if the group of covering translations of the covering space of a compact, connected, -irreducible 3-manifold corresponding to a non-trivial, finitely-generated subgroup of its fundamental group is infinite, then either the covering space is almost compact or the subgroup is infinite cyclic and has normalizer a non-finitely-generated subgroup of the rational numbers. In the first case additional information is obtained which is then used to relate Thurston's hyperbolization and virtual bundle conjectures to some algebraic conjectures about certain 3-manifold groups. 相似文献
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Let Y be a path-connected subset of a CAT(0) space Z, allowing for a map to a 1-dimensional separable metric space X, such that the nontrivial point preimages of f form a null sequence of convex subsets of Z. Such Y need not be homotopy equivalent to a 1-dimensional space.
We prove that Y admits a generalized universal covering space, which we equip with an arc-smooth structure by consistently and continuously selecting one tight representative from each path homotopy class of Y. It follows that all homotopy groups of Y vanish in dimensions greater than 1. 相似文献
17.
Kenneth A. Brakke 《Journal of Geometric Analysis》1995,5(4):445-514
A new mathematical model of soap films is proposed, called the “covering space model.” The two sides of a film are modeled
as currents on different sheets of a covering space branching along the film boundary. Hence a film may be seen as the minimal
cut separating one sheet of the covering space from the others. The film is thus the oriented boundary of one sheet, which
represents the exterior of the film. As oriented boundaries, films may be calibrated with differential forms on the covering
space, a version of the min-cut, max-flow duality of network theory. This model applies to unoriented films, films with singularities,
films touching only part of a knotted curve, films that deformation retract to their boundaries, and other examples that have
proved troublesome for previous soap film models.
Communicated by Frederick Almgren 相似文献
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We study the preservation of selective covering properties, including classic ones introduced by Menger, Hurewicz, Rothberger, Gerlits and Nagy, and others, under products with some major families of concentrated sets of reals. 相似文献
20.
Some infinite family is constructed of orientable three-dimensional closed manifoldsM
n
(p, q), where n ≥ 2, p ≥ 3, 0 < q < p, and (p, q) = 1, such that M
n
(p, q) is an n-fold cyclic covering of the lens space L(p, q) branched over a two-component link. 相似文献