منابع مشابه
Algorithms for recognizing knots and 3-manifolds
Algorithms are of interest to geometric topologists for two reasons. First, they have bearing on the decidability of a problem. Certain topological questions, such as finding a classification of four dimensional manifolds, admit no solution. It is important to know if other problems fall into this category. Secondly, the discovery of a reasonably efficient algorithm can lead to a computer progr...
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Using a recent result of Bessières-Lafontaine-Rozoy, it is proved that any 3-manifold which admits a Yamabe metric of maximal positive scalar curvature is necessarily a spherical spaceform S/Γ, and the metric is the round metric on S/Γ. On all other 3-manifolds admitting a metric of positive scalar curvature, any maximizing sequence of Yamabe metrics has curvature diverging to infinity in L.
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Using two dimensional (2D) N = 4 sigma model, with U(1) gauge symmetry, and introducing the ADE Cartan matrices as gauge matrix charges, we build ” toric” hyperKahler eight real dimensional manifolds X8. Dividing by one toric geometry circle action of X8 manifolds, we present examples describing quotients X7 = X8 U(1) of G2 holonomy. In particular, for the Ar Cartan matrix, the quotient space i...
متن کاملRepresenting and Recognizing 3-Manifolds Obtained from I-Bundles over the Klein Bottle
As it is well-known, the boundary of the orientable I-bundle K ∼ × I over the Klein bottle K is a torus; thus in analogy with torus bundle construction (see [18]) any integer matrix A of order two with determinant −1 (resp. +1) uniquely defines an orientable (resp. non-orientable) 3manifold (K ∼ ×I)∪(K ∼ ×I)/A, which we denote by KB(A). In the present paper an algorithmic procedure is described...
متن کاملNonlinear Sigma Models and Symplectic Geometry on Loop Spaces of (Pseudo)Riemannian Manifolds
In this paper we consider symplectic and Hamiltonian structures of systems generated by actions of sigma-model type and show that these systems are naturally connected with specific symplectic geometry on loop spaces of Riemannian and pseudoRiemannian manifolds. † On leave of absence from VNIIFTRI, Mendeleevo, Moscow Region 141570, Russia 1
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ژورنال
عنوان ژورنال: Proceedings of the American Mathematical Society
سال: 1985
ISSN: 0002-9939
DOI: 10.1090/s0002-9939-1985-0792291-4