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This paper is a modified chapter of the author's Ph.D. thesis. We introduce the notions of sequentially approximated types and sequentially approximated Keisler measures. As the names imply, these are types which can be approximated by a…

Logic · Mathematics 2021-12-13 Kyle Gannon

We prove a number of results relating the concepts of Keisler measures, generic stability, randomizations, and NIP formulas. Among other things, we do the following: (1) We introduce the notion of a Keisler-Morley measure, which plays the…

Logic · Mathematics 2023-09-04 Gabriel Conant , Kyle Gannon , James E. Hanson

We give category-theoretic reformulations of stability, NIP, NTP, and non-dividing by observing that their characterisations in terms of indiscernible sequences are naturally expressed as Quillen lifting properties %(negation) of certain…

Logic · Mathematics 2020-10-20 Misha Gavrilovich

As consequence of the VC theorem, any pseudo-finite measure over an NIP ultraproduct is generically stable. We demonstrate a converse of this theorem and prove that any finitely approximable measure over an ultraproduct is itself…

Logic · Mathematics 2024-07-08 Kyle Gannon

We study stable like behaviour in first order theories without the independence property. We introduce generically stable measures, give characterizatiions, and show their ubiquity. We also introduce generic compact domination. We also…

Logic · Mathematics 2010-02-26 Ehud Hrushovski , Anand Pillay , Pierre Simon

For a NIP theory $T$, a sufficiently saturated model $\mathfrak{C}$ of $T$, and an invariant (over some small subset of $\mathfrak{C}$) global type $p$, we prove that there exists a finest relatively type-definable over a small set of…

Logic · Mathematics 2025-07-16 Krzysztof Krupiński , Adrián Portillo

In NIP theories, generically stable Keisler measures can be characterized in several ways. We analyze these various forms of "generic stability" in arbitrary theories. Among other things, we show that the standard definition of generic…

Logic · Mathematics 2020-05-22 Gabriel Conant , Kyle Gannon

We study invariant types in NIP theories. Amongst other things: we prove a definable version of the (p,q)-theorem in theories of small or medium directionality; we construct a canonical retraction from the space of M-invariant types to that…

Logic · Mathematics 2015-11-10 Pierre Simon

We initiate a systematic study of the convolution operation on Keisler measures, generalizing the work of Newelski in the case of types. Adapting results of Glicksberg, we show that the supports of generically stable (or just definable,…

Logic · Mathematics 2021-01-19 Artem Chernikov , Kyle Gannon

In an important (yet unpublished) research note, Ben Yaacov describes how to turn a global Keisler measures into a type over a monster model of the randomization. This transfer methods allow one to turn questions involving measures into…

Logic · Mathematics 2024-02-09 Kyle Gannon

This paper is a sequel to [1] and considers definability in differential-henselian monotone fields with c-map and angular component map. We prove an Equivalence Theorem among whose consequences are a relative quantifier reduction and an NIP…

Logic · Mathematics 2018-06-11 Tigran Hakobyan

We discuss two constructions for obtaining generically stable Keisler measures in an NIP theory. First, we show how to symmetrize an arbitrary invariant measure to obtain a generically stable one from it. Next, we show that suitable…

Logic · Mathematics 2012-08-14 Pierre Simon

The main results in this note concern the characterization of the length of continua 1 (Theorems 2.5) and the parametrization of continua with finite length (Theorem 4.4). Using these results we give two independent and relatively…

Classical Analysis and ODEs · Mathematics 2017-10-06 Giovanni Alberti , Martino Ottolini

We note that Pillay's result on the stability of an algebraically closed field with a predicate for a group of Lang type implies that number uniformity follows formally from the finiteness results analogous to Faltings' Theorem.

Logic · Mathematics 2007-05-23 Thomas Scanlon

We prove that a wide Morley sequence in a wide generically stable type is isometric to the standard basis of an $\ell_p$ space for some $p$.

Logic · Mathematics 2019-10-25 Alexander Usvyatsov

We give a new proof of the NIP arithmetic regularity lemma for finite groups (due to the authors and Pillay), which describes the approximate structure of "NIP sets" in finite groups, i.e., subsets whose collection of left translates has…

Combinatorics · Mathematics 2025-09-05 G. Conant , C. Terry

We give sufficient conditions for a first order expansion of the real line to define the standard model of the monadic second order theory of one successor. Such an expansion does not satisfy any of the combinatorial tameness properties…

Logic · Mathematics 2016-12-07 Philipp Hieronymi , Erik Walsberg

The notion of a complete type can be generalized in a natural manner to allow assigning a value in an arbitrary Boolean algebra B to each formula. We show some basic results regarding the effect of the properties of B on the behavior of…

Logic · Mathematics 2022-01-19 Itay Kaplan , Ori Segel , Saharon Shelah

We prove the analogue of the Martingale Convergence Theorem for polynomial spline sequences. Given a natural number $k $ and a sequence $(t_i)$ of knots in $[0,1]$ with multiplicity $\le k-1$, we let $P_n $ be the orthogonal projection onto…

Functional Analysis · Mathematics 2019-09-17 Paul F. X. Müller , Markus Passenbrunner

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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