A note on stable Kim-forking
We define weak stable Kim-forking, a notion that generalizes stable forking to the context of NSOP1 theories. We adapt some of the known results on stable forking to this context.
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arXiv subjects
Yvon Bossut
Publications and source records attributed to Yvon Bossut.
Looking for stabilizers in NSOP$\_1$
In this work we study some examples of groups definable and type-definable in NSOP1 theories. We exhibit some behaviors of these groups that differ from the ones of simple groups. We take interest in the notions of generics and stabilizers, and define the Kim-stabilizer. We apply the notion of Kim-stabilizer and the stabilizer from Hrushovsky to the context of a group G definable in an NSOP1 field F satisfying some assumptions to show that there is a finite to one embedding of a type definable subgroup of G of bounded index into an algebraic group over F. We then show that definable groups in omega-free PAC fields satisfy these conditions.
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On some Fraisse limits with free amalgamation
In the first part of this work the notion of stable Kim-forking is discussed and some context on this matter is given. In the second part a general way of building some examples of NSOP1 theories as the limit of some Fraisse class satisfying stronger conditions is given. These limits will satisfy existence, that Kim-independence coincide with algebraic independence, and that forking independence is obtained by forcing base monotonicity on Kim-forking over arbitrary sets. These theories also come with a stationary independence relation. This study is based on the results of Baudisch, Ramsey, Chernikov and Kruckman.
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A note on some example of NSOP1 theories
We present here some known and some new examples of non-simple NSOP1 theories and some behaviour that Kim-forking can exhibit in these theories, in particular that Kim-forking after forcing base monotonicity can or can not satisfy extension (on arbitrary sets). This study is based on the results of Chernikov, Ramsey, Dobrowolski and Granger.
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Kim-forking for hyperimaginaries in NSOP1 theories
We adapt the properties of Kim-independence in NSOP1 theories with existence proven in [5],[4] and [2] by Ramsey, Kaplan, Chernikov, Dobrowolski and Kim to hyperimaginaries by adding the assumption of existence for hyperimaginaries. We show that Kim-independence over hyperimaginaries satisfies a version of Kim's lemma, symmetry, the independence theorem, transitivity and witnessing. As applications we adapt Kim's results around colinearity and weak canonical bases from [8] to hyperimaginaries and give some new results about Lascar strong types and Kim-forking using boundedly closed hyperimaginaries.
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