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We study the $C^*$-algebras associated to upper-semicontinuous Fell bundles over second-countable Hausdorff groupoids. Based on ideas going back to the Packer--Raeburn "Stabilization Trick," we construct from each such bundle a groupoid…

Operator Algebras · Mathematics 2016-05-23 Marius Ionescu , Alex Kumjian , Aidan Sims , Dana P. Williams

We prove that if $T$ is a complete theory with weak elimination of imaginaries, then there is an explicit bijection between strict independence relations for $T$ and strict independence relations for $T^{\text{eq}}$. We use this observation…

Logic · Mathematics 2018-09-12 Gabriel Conant

We introduce tame abstract elementary classes as a generalization of all cases of abstract elementary classes that are known to permit development of stability-like theory. In this paper we explore stability results in this context. We…

Logic · Mathematics 2007-05-23 Rami Grossberg , Monica VanDieren

We prove a long exact sequence in KK-theory for both full and reduced amalgamated free products in the presence of conditional expectations. In the course of the proof, we established the KK-equivalence between the full amalgamated free…

Operator Algebras · Mathematics 2016-12-28 Pierre Fima , Emmanuel Germain

Understanding how singularities behave under small perturbations is a central theme in singularity theory. In this paper we establish sufficient conditions for families of analytic function-germs on a germ of a complex analytic space to…

Algebraic Geometry · Mathematics 2025-12-04 R. Giménez Conejero , Andreas Lind , Aurélio Menegon

By using the decomposition of the decoherence-free subalgebra N(T) in direct integrals of factors, we obtain a structure theorem for every uniformly continuous QMSs. Moreover we prove that, when there exists a faithful normal invariant…

Quantum Physics · Physics 2021-01-14 Emanuela Sasso , Veronica Umanità

We construct a notion of derived completion which applies to homomorphisms of commutative S-algebras. We study the relationship of the construction with other constructions of completions, and prove various invariance properties. The…

Algebraic Topology · Mathematics 2007-07-18 Gunnar Carlsson

In this PhD thesis, we give a new geometric approach to higher Teichm\"uller theory. In particular we construct a geometric structure on surfaces, generalizing the complex structure, and we explore its link to Hitchin components. The…

Differential Geometry · Mathematics 2020-07-02 Alexander Thomas

The theory of optimal choice sets offers a well-established solution framework in social choice and game theory. In social choice theory, decision-making is typically modeled as a maximization problem. However, when preferences are cyclic…

General Economics · Economics 2025-08-14 Athanasios Andrikopoulos , Nikolaos Sampanis

We construct a higher Whitehead torsion map, using algebraic K-theory of spaces, and show that it satisfies the usual properties of the classical Whitehead torsion. This is used to describe a "geometric assembly map" defined on stabilized…

K-Theory and Homology · Mathematics 2014-02-26 Wolfgang Steimle

In this paper, we propose an abstract definition of dependent type theories as essentially algebraic theories. One of the main advantages of this definition is its composability: simple theories can be combined into more complex ones, and…

Logic · Mathematics 2017-03-28 Valery Isaev

We introduce a new device in the study of abstract elementary classes (AECs): Galois Morleyization, which consists in expanding the models of the class with a relation for every Galois type of length less than a fixed cardinal $\kappa$. We…

Logic · Mathematics 2016-05-02 Sebastien Vasey

The goal of this paper is to study when uniform Roe algebras have certain $C^*$-algebraic properties in terms of the underlying space: in particular, we study properties like having stable rank one or real rank zero that are thought of as…

Operator Algebras · Mathematics 2018-01-31 Kang Li , Rufus Willett

We introduce the notion of the algebraic overshear density property which implies both the algebraic notion of flexibility and the holomorphic notion of the density property. We investigate basic consequences of this stronger property, and…

Complex Variables · Mathematics 2023-10-31 Rafael B. Andrist , Frank Kutzschebauch

We study quasiminimal classes, i.e. abstract elementary classes (AECs) that arise from a quasiminimal pregeometry structure. For these classes, we develop an independence notion, and in particular, a theory of independence in $\M^{eq}$. We…

Logic · Mathematics 2014-04-29 Kaisa Kangas

I prove several theorems concerning upward closure and amalgamation in the generic multiverse of a countable transitive model of set theory. Every such model $W$ has forcing extensions $W[c]$ and $W[d]$ by adding a Cohen real, which cannot…

Logic · Mathematics 2015-11-04 Joel David Hamkins

The Kasparov absorption (or stabilization) theorem states that any countably generated Hilbert C*-module is isomorphic to a direct summand in the standard module of square summable sequences in the base C*-algebra. In this paper, this…

Operator Algebras · Mathematics 2014-07-08 Jens Kaad

Motivated by structural properties of differential field extensions, we introduce the notion of a theory $T$ being derivation-like with respect to another model complete theory $T_0$. We prove that when $T$ admits a model companion $T_+$,…

Logic · Mathematics 2025-03-25 Omar Leon Sanchez , Shezad Mohamed

We exhibit a connection between geometric stability theory and the classification of unstable structures at the level of simplicity and the $\mathrm{NSOP}_{1}$-$\mathrm{SOP}_{3}$ gap. Particularly, we introduce generic expansions $T^{R}$ of…

Logic · Mathematics 2023-05-31 Scott Mutchnik

An amalgam of inverse semigroups [S,T,U] is full if U contains all of the idempotents of S and T. We show that for a full amalgam [S,T,U], the C*-algebra of the inverse semigroup amaglam of S and T over U is the C*-algebraic amalgam of…

Operator Algebras · Mathematics 2010-07-08 Allan P Donsig , Steven P. Haataja , John C. Meakin