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arXiv research

A locally-built, LLM-digested index of recent arXiv papers in quant finance, geometry/topology, and statistical ML — keyword search served straight from SQLite on this machine.

169,291 papers · 148 categories

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48 results for Bass-Serre theory

The paper studies actions on Bass-Serre trees and identifies new CC^*-simple groups.

problem Investigating actions of fundamental groups on Bass-Serre trees and their CC^*-algebraic properties.
method Analyzing boundary actions of fundamental groups of graphs of groups on their Bass-Serre trees.
result Identification of new families of CC^*-simple groups, including tubular groups and certain graphs of groups.

The paper extends group constructions to coset geometries, creating new ways to combine geometries.

problem Combining and gluing incidence geometries in a general framework.
method Extending classical group-theoretic constructions to coset geometries.
result Provides a general framework for combining or gluing incidence geometries.

In geometric group theory one uses group actions on spaces to gain information about groups. One natural space to use is the Cayley graph of a group. The Cayley graph arguments that one encounters tend to require local finiteness, and hence finite generation of the group. In this paper, I take the theory of intersectio…

2011-05-27abs ↗pdf ↗

This paper addresses questions of quasi-isometric rigidity and classification for fundamental groups of finite graphs of groups, under the assumption that the Bass-Serre tree of the graph of groups has finite depth. The main example of a finite depth graph of groups is one whose vertex and edge groups are coarse Poinca…

2004-05-13abs ↗pdf ↗

Study non-vanishing 2\ell^2-Betti numbers for specific groups.

problem Calculating non-vanishing 2\ell^2-Betti numbers for certain groups.
method Using Euler characteristics, higher Kazhdan projections, and Baum-Connes assembly map.
result Non-vanishing calculations for delocalised 2\ell^2-Betti numbers.

The thesis shows how automorphisms of hyperbolic groups can be represented by train track maps.

problem Representing automorphisms of hyperbolic groups using train track maps.
method Using graphs of groups and Bestvina-Handel's irreducible train track maps, the thesis constructs relative train track maps.
result Outer automorphisms of finitely-generated word hyperbolic groups satisfy a dynamical trichotomy.

The Farrell-Jones Conjecture holds for groups acting acylindrically on trees.

problem Verifying the Farrell-Jones Conjecture for groups acting on trees.
method Analyzing acylindrical actions on simplicial trees and using the Farrell-Jones Conjecture.
result The Farrell-Jones Conjecture holds for groups acting acylindrically on trees.

We define a new notion of contracting element of a group and we show that contracting elements coincide with hyperbolic elements in relatively hyperbolic groups, pseudo-Anosovs in mapping class groups, rank one isometries in groups acting properly on proper CAT(0) spaces, elements acting hyperbolically on the Bass-Serr…

2011-12-12abs ↗pdf ↗

This is an account of the theory of JSJ decompositions of finitely generated groups, as developed in the last twenty years or so. We give a simple general definition of JSJ decompositions (or rather of their Bass-Serre trees), as maximal universally elliptic trees. In general, there is no preferred JSJ decomposition, a…

2016-02-16abs ↗pdf ↗

We give an example of a subgroup of SL(2,C) which is a strictly ascending HNN extension of a non-abelian finitely generated free group F. In particular, we exhibit a free group F in SL(2,C) of rank 6 which is conjugate to a proper subgroup of itself. This answers positively a question of Drutu and Sapir. The main ingre…

2004-12-07abs ↗pdf ↗

The paper studies acylindrical actions on trees and proves acylindrical hyperbolicity of Baumslag-Solitar groups.

problem Exploring acylindrical actions on trees and their properties.
method Demonstrates criteria for preserving acylindrical hyperbolicity and analyzes the outer automorphism group of Baumsligar-Solitar groups.
result Proves acylindrical hyperbolicity of non-solvable Baumsligar-Solitar groups.

Study boundary actions of CAT(0) spaces and their CC^*-algebras.

problem Investigate boundary actions of CAT(0) spaces and their associated CC^*-algebras.
method Topological dynamics and CC^*-algebras, focusing on actions of specific groups and their properties.
result Established (strongly) pure infiniteness results for reduced crossed product CC^*-algebras of boundary actions.

The paper connects function theory, dynamics, and ergodic theory via Thurston's theory.

problem Function theory on Teichmüller space and dynamics of mapping class groups.
method Utilizes Thurston's theory and Sullivan's theory on discrete subgroups of hyperbolic space.
result Establishes connections between function theory, dynamics, and ergodic theory.

Lectures on topological field theories and differential cohomology.

problem Exploring topological field theories and their connections to differential cohomology.
method Introduction to topological field theory and generalized Abelian gauge theories.
result Explains the relationship between topological field theories and differential cohomology.

The paper defines strong emergence in field theories and proves it exists between certain theories.

problem Defining and proving the existence of strong emergence phenomena between field theories.
method Formal definition and sufficient conditions for emergence, proving existence in Euclidean background.
result Strong emergence exists between certain parameterized Lagrangian field theories.

Researchers solve M-theory's gauge enhancement problem using advanced homotopy theory.

problem Lift nonabelian gauge fields from D-branes to M-theory.
method Universal constructions in super homotopy theory, focusing on the cyclification adjunction and fiberwise stabilization.
result Gauge enhancement in M-theory is explained by lifting against the fiberwise stabilization of the unit of the cyclification adjunction.

Researchers find new G2G_2-conifolds in MM-theory with potential field theory duals.

problem Exploring the field theory interpretation of MM-theory G2G_2-conifolds.
method Constructing G2G_2-holonomy orbifolds from circle bundles over Calabi-Yau cones.
result Many UV perturbative gauge theories have an infrared dual described by smooth G2G_2-holonomy backgrounds in MM-theory.

We survey three different ways in which K-theory in all its forms enters quantum field theory. In Part 1 we give a general argument which relates topological field theory in codimension two with twisted K-theory, and we illustrate with some finite models. Part 2 is a review of pfaffians of Dirac operators, anomalies, a…

2002-06-18abs ↗pdf ↗

Distributivity in algebraic structures appeared in many contexts such as in quasigroup theory, semigroup theory and algebraic knot theory. In this paper we give a survey of distributivity in quasigroup theory and in quandle theory.

2012-09-28abs ↗pdf ↗

Main mathematical applications of Frobenius manifolds are in the theory of Gromov - Witten invariants, in singularity theory, in differential geometry of the orbit spaces of reflection groups and of their extensions, in the hamiltonian theory of integrable hierarchies. The theory of Frobenius manifolds establishes rema…

1998-07-08abs ↗pdf ↗

This thesis proposes a global geometric formulation of Extended Field Theories.

problem Global understanding of Extended Field Theories remains an open problem.
method Introducing an atlas for the principal infinity-bundle, unifying metric and higher gauge field.
result Global abelian T-duality and Poisson-Lie T-duality are automatically recovered.

The paper quantizes hybrid topological-holomorphic field theories on RmimesCn\mathbb{R}^m imes \mathbb{C}^n.

problem Quantizing hybrid topological-holomorphic field theories rigorously.
method Constructing perturbative, one-loop quantizations on RmimesCn\mathbb{R}^m imes \mathbb{C}^n.
result The one-loop obstruction to quantization vanishes when m1m \geq 1.

This is the revised version of the second paper in a series introducing a generalized Fredholm theory in a new class of smooth spaces called polyfolds. The theory will be illustrated in upcoming papers by applications to Floer Theory, Gromov-Witten Theory and Symplectic Field Theory. Some proofs have been improved and …

2007-05-09abs ↗pdf ↗

Topological field theories of 2- and 3-forms in 6D, showing no propagating degrees of freedom.

problem Exploring field theories of 2- and 3-forms in six dimensions.
method Analyzing field theories with kinetic term BdCBdC and varying potential terms.
result The theories remain topological even with added potential terms, and their reductions yield 3D gravity.