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Seminář - 24.9.2018 od 10:00 v M5 |
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The seminar on Differential geometry will start on Monday, September 24, 2018, at 10.00, in the lecture room M5 with the first lecture
Henrik Winther:Symmetries of complex submanifolds of quaternionic manifolds Abstract:
The generalized Feix construction (by A.Borowka, D.Calderbank) identifies c-projective manifolds with type 1,1 curvature with the totally complex submanifolds of quaternionic manifolds. Our goal is to investigate the relationship between c-projective symmetries and quaternionic symmetries in this setting. We will show when a symmetry can be lifted to the quaternionic manifold. Moreover, we show that any maximally- or sub-maximally symmetric quaternionic manifold arises from the construction, for some c-projective manifold. In particular, a (sub-)maximally symmetric c-projective manifold can be used to construct a (sub-)maximally symmetric quaternionic manifold. This is a joint work with A. Borowka. |
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Aktualizováno Středa, 03 Říjen 2018 14:53 |
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Seminář - 20.9.2018 od 13:00 v M5 |
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Seminář proběhne 20.9.2018 od 13:00 v posluchárně M5.
C. Espindola:
Omitting types theorem, conceptual completeness and definability for infinitary logic Abstract:
We will start by presenting a sheaf-theoretic version of the classical omitting types theorem that generalizes to infinitary logic as a corollary of the infinitary version of Deligne's completeness theorem. This allows to transfer to the infinitary case the classical theorems about atomic and prime models, and also an infinitary version of the Ryll-Nardewski theorem characterizing categorical theories. As a side result during the proof, we will derive a strong version of Löwenheim-Skolem theorem that will allow to provide a reconstruction result for infinitary theories through a semantic site for the classigying topos. This latter presentation entails both conceptual completeness and definability theorems. |
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Aktualizováno Pondělí, 17 Září 2018 17:22 |
