Bordism of oriented 5-manifolds with T-structure and polarization
Piotr Mikrut (1999)
Colloquium Mathematicae
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Piotr Mikrut (1999)
Colloquium Mathematicae
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Mattias Dahl (1997)
Banach Center Publications
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We show what extra condition is necessary to be able to use the positive mass argument of Witten [12] on an asymptotically locally euclidean manifold. Specifically we show that the 'generalized positive action conjecture' holds if one assumes that the signature of the manifold has the correct value.
Martin Čadek, Jiří Vanžura (1998)
Banach Center Publications
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The paper is an overview of our results concerning the existence of various structures, especially complex and quaternionic, in 8-dimensional vector bundles over closed connected smooth 8-manifolds.
Martin Cadek, Jirí Vanzura (1997)
Publicacions Matemàtiques
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Let ξ be an oriented 8-dimensional vector bundle. We prove that the structure group SO(8) of ξ can be reduced to S(2) or S(2) · S(1) if and only if the vector bundle associated to ξ via a certain outer automorphism of the group Spin(8) has 3 linearly independent sections or contains a 3-dimensional subbundle. Necessary and sufficient conditions for the existence of an S(2)- structure in ξ over a closed connected spin manifold of dimension 8 are also given in terms of characteristic classes. ...
David C. Tischler, Rosamond W. Tischler (1974)
Annales de l'institut Fourier
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For actions as in the title we associate a collection of rotation numbers. If one of them is sufficiently irrational then the action is conjugate (as an action) to either a linear action on a torus or to an action on a principal bundle over with orbits.
Krzysztof Pawałowski (1996)
Mathematica Slovaca
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Marco Andreatta, Jarosław A. Wiśniewski (2003)
Bollettino dell'Unione Matematica Italiana
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We consider a smooth projective variety on which a simple algebraic group acts with an open orbit. We discuss a theorem of Brion-Luna-Vust in order to relate the action of with the induced action of on the normal bundle of a closed orbit of the action. We get effective results in case and .