Study on geometry and dynamics of transverse subgroups.
problem Understanding the geometry and dynamics of transverse subgroups.
method Survey of recent research on semi-simple Lie groups.
result Recent findings on transverse subgroups of semi-simple Lie groups.
New theorem on subgroup dynamics of Out(F_N).
problem Understanding subgroups of Out(F_N).
method Analogous to Ivanov's and Handel-Mosher's theorems.
result Subgroups either contain atoroidal elements or fix conjugacy classes.
Extends Anosov subgroup definitions to more general groups.
problem Characterize subgroups of semisimple Lie groups.
method Relativizes characterizations of Anosov subgroups.
result Proves implications and equivalences between relativized characterizations.
We study infinite covolume discrete subgroups of higher rank semisimple Lie groups, motivated by understanding basic properties of Anosov subgroups from various viewpoints (geometric, coarse geometric and dynamical). The class of Anosov subgroups constitutes a natural generalization of convex cocompact subgroups of ran…
The paper tackles fairness in forecasting and learning linear dynamical systems.
problem Under-representation bias in training data for multiple subgroups.
method Introducing subgroup-fair and instant-fair learning of LDS from multiple trajectories of varying lengths, using hierarchies of convexifications of non-commutative polynomial optimisation problems.
result Empirical results show both the beneficial impact of fairness considerations on statistical performance and encouraging effects of exploiting sparsity on run time.
In this paper, we prove a limit set intersection theorem in relatively hyperbolic groups. Our approach is based on a study of dynamical quasiconvexity of relatively quasiconvex subgroups. Using dynamical quasiconvexity, many well-known results on limit sets of geometrically finite Kleinian groups are derived in general…
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.
Polynomial growth elements found in all subgroups of Out(F_n).
problem Understanding polynomial growth in subgroups of Out(F_n).
method Analyzing conjugacy classes and elements of Out(F_n).
result Polynomial growth elements exist in all subgroups of Out(F_n).
Formula for subgroup growth in mapping class groups.
problem Growth of subgroups in mapping class groups.
method Asymptotic growth formula with Teichmüller metric.
result Asymptotic growth formula for subgroups.
We prove a Morse Lemma for coarsely regular quasigeodesics in nonpositively curved symmetric spaces and euclidean buildings X. The main application is a simpler coarse geometric characterization of Morse subgroups of the isometry groups Isom(X) as undistorted subgroups which are coarsely uniformly regular. We show furt…
This survey is based on a series of lectures that we gave at MSRI in Spring 2015 and on a series of papers, mostly written jointly with Joan Porti. Our goal here is to: 1. Describe a class of discrete subgroups Γ<G of higher rank semisimple Lie groups, which exhibit some "rank 1 behavior". 2. Give different character…
The theme of this survey is that subgroups of the mapping class group of a finite type surface S can be studied via the geometric/dynamical properties of their action on the Thurston compactification of the Teichmuller space of S, just as discrete subgroups of the isometries of hyperbolic space can be studied via their…
New method learns from subgroup feedback in complex systems.
problem Optimizing complex systems with heterogeneous components.
method Decomposed Gaussian Process (GP) regression and optimization algorithm.
result Proved lower variance and improved accuracy in subgroup feedback.
Recent advances in discrete subgroups of SL2(C) influenced by Thurston's work.
problem The dynamics of discrete subgroups of SL2(C)
method Discussion of recent advances in the topic
result Influenced by Thurston's work, recent advances have been made in the dynamics of discrete subgroups of SL2(C)
Constructs flows on quotients of Lie groups for Anosov subgroups.
problem Understanding dynamics on quotients of Lie groups by Anosov subgroups.
method Utilizes geometric structures and Lie group theory to construct and analyze flows.
result Establishes that all refraction flows arise from this construction.
Paper proves non-arithmetic Teichmüller length spectra for subgroup of mapping class groups.
problem Proving non-arithmetic Teichmüller length spectra for subgroups of mapping class groups.
method Introducing cross-ratios on Teichmüller and projectable mapping classes, studying their geometric and dynamical properties.
result Every non-elementary subgroup of the mapping class group has non-arithmetic Teichmüller length spectrum.
A sliding surface stabilizes rigid body attitude control.
problem Stabilizing rigid body attitude control robustly.
method Proposed sliding surface as Lie subgroup, designed sliding-mode controller.
result Closed-loop system is robust against disturbances and unwinding.
We study different notions of quasiconvexity for a subgroup H of a relatively hyperbolic group G. The first result establishes equivalent conditions for H to be relatively quasiconvex. As a corollary we obtain that the relative quasiconvexity is equivalent to the dynamical quasiconvexity. This answers to a questi…
Study counts surface subgroups in curved 3D manifolds.
problem Count surface subgroups in curved 3D manifolds.
method Solve foliated Plateau problem in Cartan-Hadamard manifolds.
result Prove rigidity for lower bound on surface subgroup count.
Characterizes convex cocompact actions in projective space with dynamical properties.
problem Understanding convex cocompact group actions in projective space.
method Dynamical characterization and expansion property analysis.
result Equivalence of convex cocompactness to an expansion property in different Grassmannians.
We prove that all atoroidal automorphisms of Out(FN) act on the space of projectivized geodesic currents with generalized north-south dynamics. As an application, we produce new examples of non virtually cyclic, free and purely atoroidal subgroups of Out(FN) such that the corresponding free group extension is hyp…
In this paper, we characterize the dynamic of every abelian subgroups G of GL(n, K), K=R or C. We show that there exists a G-invariant, dense open set U in Kn saturated by minimal orbits with Kn−U a union of at most n…
For a convex cocompact subgroup G<Mod(S), and points x,y∈Teich(S) we obtain asymptotic formulas as R→∞ of ∣BR(x)∩Gy∣ as well as the number of conjugacy classes of pseudo-Anosov elements in G of dilatation at most R. We do this by developing an analogue of Patterson-Sullivan theory for the…
A new dynamical approach connects resolution cohomology to group representations.
problem Establishing a bijection between resolution cohomology and group representations.
method Gauge-theoretic Morse flow on the minimal resolution.
result The flow converges to specific irreducible representations of the group.
Study subgroups preserving proper domains in flag manifolds.
problem Identify subgroups preserving proper domains in flag manifolds.
method Establish necessary conditions and introduce causal convexity in Shilov boundary.
result Transverse subgroups with geometric properties in Shilov boundary.
The Tits alternative for Out(F_n) is reduced to the case where all elements in the subgroup under consideration grow polynomially.
Defines new representations for hyperbolic groups, unifying existing definitions.
problem Geometrically finite behavior in higher rank groups.
method Introduces a new family of discrete representations for relatively hyperbolic groups.
result Stability of these representations under certain deformations.
Study compact plane waves, showing they are essentially standard.
problem Understanding the topology and dynamics of compact plane waves.
method Analyzing quotients of homogeneous plane waves by discrete subgroups.
result Compact quotients of homogeneous plane waves are essentially standard.
Book introduces Hofer's metric on symplectic diffeomorphisms.
problem Understanding dynamics and growth in symplectic geometry.
method Introduces Hofer's metric and analyzes its properties.
result Provides insights into the structure of symplectic diffeomorphisms.
Study invariant measures on measured laminations for subgroups of mapping class group.
problem Classify invariant Radon measures on space of measured laminations for subgroups of mapping class group.
method Geometric approach, focusing on recurrent measured laminations, explicitly constructing ergodic measures.
result Show uniquely ergodic for divergence-type subgroups, generalize results for full mapping class group.
The paper studies automorphisms of free groups with a North-South dynamics.
problem Characterizing automorphisms of free groups with dynamical properties.
method Analyzes the action of outer automorphisms on a relative space of currents.
result Proves the existence of a preferred compact space on which automorphisms act with North-South dynamics.
Empirical study on rich subgroup fairness for machine learning.
problem Ensuring fairness across large subgroups in machine learning.
method An algorithm that learns subject to rich subgroup fairness constraints.
result Rich subgroup fairness leads to large gains in fairness with mild accuracy costs.
Random walks on groups yield infinitely many normal subgroups and exponential growth rates.
problem Understanding normal subgroups and growth rates in random walks on groups.
method Analyzing random walks on groups of isometries of non-proper delta-hyperbolic spaces under WPD condition.
result The probability that the normal closure of random elements is free tends to 1, and the dynamical degree of random Cremona transformations grows exponentially.
Study ping-pong dynamics in hyperbolic-like groups with non-simple points.
problem Investigate the ping-pong dynamics of hyperbolic-like groups.
method Explicitly provide a proper ping-pong partition for any pair of non-cyclic point stabilizers.
result Existence of a proper ping-pong partition for any pair of non-cyclic point stabilizers.
Study generalizes non-interaction theorems for relativistic systems.
problem Understanding interactions in relativistic and non-relativistic systems.
method Generalizes non-interaction theorems for Lorentz violating systems and Galilei invariant systems.
result Extends analysis to very special relativity and anisotropic systems.
New method studies automorphism groups of Platonic surfaces.
problem Understanding the automorphism groups of Platonic surfaces.
method Unfolding construction and monodromy group analysis.
result Explicit bounds on cyclic quotient groups of Platonic surfaces.
ShapShift explains shifts in model predictions due to data distribution changes.
problem Prediction shifts caused by changes in input distribution.
method Subgroup Conditional Shapley Values applied to decision trees and ensembles.
result Simple, faithful, and near-complete explanations of prediction shifts across model classes.
Let Γ<SL2(Z) be a non-elementary finitely generated subgroup and let Γ(q) be its congruence subgroup of level q for each q∈N. We obtain an asymptotic formula for the matrix coefficients of L2(Γ(q)\SL2(R)) with a {\it uniform} exponential error term…
Study on G2-type flag manifolds, focusing on invariant metrics and Ricci flow.
problem Characterizing and analyzing metrics on G2-type flag manifolds. method Investigation of invariant metrics, analysis of g.o. metrics, and Ricci flow techniques.
result Characterization of metrics invariant under maximal compact subgroups.
We consider the space of all representations of the commutator subgroup of a knot group into Z/p, p is prime. As proven by D. Silver and S. Williams, this space can be completely described by a finite oriented graph. We describe the lengths of cycles in this graph.
We study the geometry and dynamics of discrete infinite covolume subgroups of higher rank semisimple Lie groups. We introduce and prove the equivalence of several conditions, capturing "rank one behavior'' of discrete subgroups of higher rank Lie groups. They are direct generalizations of rank one equivalents to convex…
Study proves projective Anosov subgroups lead to mixing flows in specific spaces.
problem Understanding mixing properties of flows on specific geometric spaces.
method Constructing non-empty domain of discontinuity in homogeneous space, using spectral estimates for transfer operators.
result Exponential mixing, spectral gap, and meromorphic continuation of zeta functions established.
The study examines the structure of certain subgroups of quasi-isometry groups of Euclidean spaces, proving their nontriviality and properties.
problem Investigating the algebraic and dynamical structure of certain subgroups of quasi-isometry groups of Euclidean spaces.
method Analyzing the normal subgroups \(H\) and \(H_\alpha\) of \(QI(\mathbb{R}^n)\) and proving their properties.
result The centers of \(QI(\mathbb{R}^n)/H\) and \(QI(\mathbb{R}^n)/H_\alpha\) are trivial, while these quotients admit nontrivial torsion elements.
We study the growth of the rank of subgroups of finite index in residually finite groups, by relating it to the notion of cost. As a by-product, we show that the `Rank vs. Heegaard genus' conjecture on hyperbolic 3-manifolds is incompatible with the `Fixed Price problem' in topological dynamics.
In this note we obtain the characterization for asymptotic directions on various subgroups of the diffeomorphism group. We give a simple proof of non-existence of such directions for area-preserving diffeomorphisms of closed surfaces of non-zero curvature. Finally, we exhibit the common origin of the Monge-Ampere equat…
The study proves no L2-eigenvalues for higher rank locally symmetric spaces.
problem Absence of principal eigenvalues for higher rank locally symmetric spaces.
method Derives dynamical assumptions on the Γ-action on geodesics and Satake compactifications.
result Generalization of Patterson's result to higher rank locally symmetric spaces.
We prove uniform north-south dynamics type results for the action of φ∈Out(FN) on the space of projectivized geodesic currents PCurr(S)=PCurr(FN), where φ is induced by a pseudo-Anosov homeomorphism on a compact surface S with boundary such that π1(S)=FN. As an appli…
Dynamic cell-free networks reduce complexity in serving many devices with distributed APs and DRL.
problem Designing efficient cell-free networks with many devices and APs.
method Dynamic architecture, SIC, DAS, DRL for optimization.
result DRL significantly improves performance in dynamic cell-free networks.