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We prove several results on the behavior of Kim-independence upon changing the base in NSOP$_{1}$ theories. As a consequence, we prove that Kim-independence satisfies transitivity and that this characterizes NSOP$_{1}$. Moreover, we…

Logic · Mathematics 2020-12-08 Itay Kaplan , Nicholas Ramsey

We study Kim-independence over arbitrary sets. Assuming that forking satisfies existence, we establish Kim's lemma for Kim-dividing over arbitrary sets in an NSOP$_{1}$ theory. We deduce symmetry of Kim-independence and the independence…

Logic · Mathematics 2019-09-19 Jan Dobrowolski , Byunghan Kim , Nicholas Ramsey

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…

Logic · Mathematics 2022-10-26 Yvon Bossut

An important dividing line in the class of unstable theories is being NSOP$_1$, which is more general than being simple. In NSOP$_1$ theories forking independence may not be as well-behaved as in stable or simple theories, so it is replaced…

Logic · Mathematics 2023-03-29 Jan Dobrowolski , Mark Kamsma

We study NSOP$_{1}$ theories. We define Kim-independence, which generalizes non-forking independence in simple theories and corresponds to non-forking at a generic scale. We show that Kim-independence satisfies a version of Kim's lemma,…

Logic · Mathematics 2019-01-09 Itay Kaplan , Nicholas Ramsey

We show that NSOP$_{1}$ theories are exactly the theories in which Kim-independence satisfies a form of local character. In particular, we show that if $T$ is NSOP$_{1}$, $M\models T$, and $p$ is a type over $M$, then the collection of…

Logic · Mathematics 2018-02-13 Itay Kaplan , Nicholas Ramsey , Saharon Shelah

Tree properties are introduced by Shelah, and it is well-known that a theory has TP (the tree property) if and only if it has TP$_1$ or TP$_2$. In any simple theory (i.e., a theory not having TP), forking supplies a good independence notion…

Logic · Mathematics 2019-07-05 Enrique Casanovas , Byunghan Kim

Kim's Lemma is a key ingredient in the theory of forking independence in simple theories. It asserts that if a formula divides, then it divides along every Morley sequence in type of the parameters. Variants of Kim's Lemma have formed the…

Logic · Mathematics 2024-08-14 Alex Kruckman , Nicholas Ramsey

We introduce a family of local ranks DQ depending on a finite set Q of pairs of the form (\varphi(x,y),q(y)) where \varphi(x,y) is a formula and q(y) is a global type. We prove that in any NSOP1 theory these ranks satisfy some desirable…

Logic · Mathematics 2021-11-04 Jan Dobrowolski , Daniel Max Hoffmann

The classes stable, simple and NSOP$_1$ in the stability hierarchy for first-order theories can be characterised by the existence of a certain independence relation. For each of them there is a canonicity theorem: there can be at most one…

Logic · Mathematics 2024-05-22 Mark Kamsma

The proof of the Independence Theorem for Kim-independence in positive thick NSOP$_1$ theories from (Dobrowolski and Kamsma, 2022) contains a gap. The theorem is still true, and in this corrigendum we give a different proof.

Logic · Mathematics 2024-08-14 Jan Dobrowolski , Mark Kamsma

We show that Kim-forking satisfies existence in all NSOP$_1$ theories.

Logic · Mathematics 2025-12-30 Byunghan Kim , Joonhee Kim , Hyoyoon Lee

We initiate the study of a generalization of Kim-independence, Conant-independence, based on the "strong Kim-dividing" of Kaplan, Ramsey and Shelah. We introduce an axiom on stationary independence relations essentially generalizing the…

Logic · Mathematics 2024-01-26 Scott Mutchnik

We characterize nonforking (Morley) sequences in dependent theories in terms of a generalization of Poizat's special sequences and show that average types of Morley sequences are stationary over their domains. We characterize generically…

Logic · Mathematics 2008-10-07 Alexander Usvyatsov

We develop a framework, in the style of Adler, for interpreting the notion of "witnessing" that has appeared (usually as a variant of Kim's Lemma) in different areas of neostability theory as a binary relation between abstract independence…

Logic · Mathematics 2026-02-20 Alberto Miguel-Gómez

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…

Logic · Mathematics 2025-10-31 Yvon Bossut

We establish several results regarding dividing and forking in NTP2 theories. We show that dividing is the same as array-dividing. Combining it with existence of strictly invariant sequences we deduce that forking satisfies the chain…

Logic · Mathematics 2013-08-14 Itaï Ben Yaacov , Artem Chernikov

We show that approximations of strict order can calibrate the fine structure of genericity. Particularly, we find exponential behavior within the $\mathrm{NSOP}_{n}$ hierarchy from model theory. Let $0$-$\eth$-independence denote…

Logic · Mathematics 2023-05-31 Scott Mutchnik

We give an example of an SOP theory $T$, such that any $L(M)$-formula $\varphi(x,y)$ with $|y|=1$ is NSOP. We show that any such $T$ must have the independence property. We also give a simplified proof of Lachlan's theorem that if every…

Logic · Mathematics 2025-07-15 Will Johnson

We introduce some properties describing dependence in indiscernible sequences: $F_{ind}$ and its dual $F_{Mb}$, the definable Morley property, and $n$-resolvability. Applying these properties, we establish the following results: We show…

Logic · Mathematics 2026-04-29 John Baldwin , James Freitag , Scott Mutchnik
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