Logic Seminar
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Thu, 15/10/2009 17:00 |
Jonathan Pila (Bristol) |
Logic Seminar  |
L2 |
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Thu, 22/10/2009 17:00 |
Zoe Chatzidakis (Université Paris 7) |
Logic Seminar |
L3 |
| I will speak about the CBP (canonical base property) for types of finite SU-rank. This property first appears in a paper by Pillay and Ziegler, who show that it holds for types of finite rank in differentially closed fields of characteristic 0, as well as in existentially closed difference fields. It is unknown whether this property holds for all finite rank types in supersimple theories. I will first recall the definition of a canonical base, and give some natural examples. I will then talk about a reduction of the problem (which allows one to extend the Pillay-Ziegler result to existentially closed fields of any characteristic), and finally derive some consequences of the CBP, in particular the UCBP, thus answering a question of Moosa and Pillay. If time permits, I will show an application of these results to difference fields. | |||
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Thu, 29/10/2009 17:00 |
Deirdre Haskell (Mcmaster) |
Logic Seminar |
L3 |
| VC dimension and density are properties of a collection of sets which come from probability theory. It was observed by Laskowski that there is a close tie between these notions and the model-theoretic property called NIP. This tie results in many examples of collections of sets that have finite VC dimension. In general, it is difficult to find upper bounds for the VC dimension, and known bounds are mostly very large. However, the VC density seems to be more accessible. In this talk, I will explain all of the above acronyms, and present a theorem which gives an upper bound (in some cases optimal) on the VC density of formulae in some examples of NIP theories. This represents joint work of myself with M. Aschenbrenner, A. Dolich, D. Macpherson and S. Starchenko. | |||
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Thu, 05/11/2009 17:00 |
Anand Pillay (Leeds) |
Logic Seminar |
L3 |
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Thu, 12/11/2009 17:00 |
Philip Scowcroft (Wesleyan) |
Logic Seminar |
L3 |
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Thu, 19/11/2009 17:00 |
Florian Pop (Philadelphia) |
Logic Seminar |
L3 |
| After a short introduction to the section conjecture, I plan to present a "minimalistic" form of the birational p-adic section conjecture. The result is related to both: Koenigsmann's proof of the birational p-adic section conjecture, and a "minimalistic" Galois characterisation of formally p-adic valuations. | |||
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Thu, 26/11/2009 17:00 |
Alf Onshuus (Bogota) |
Logic Seminar |
L3 |
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Thu, 03/12/2009 17:00 |
Markus Junker (Freiburg) |
Logic Seminar |
L3 |
-categorical structures