arXiv research

Unified proof of Nielsen-Thurston classification via Teichmüller's theorem.

Researchers solve Nielsen Realization problems for K3 surfaces in various categories.

Given a topological orientable surface of finite or infinite type equipped with a pair of pants decomposition $\mathcal{P}$ and given a base complex structure $X$ on $S$, there is an associated deformation space of complex structures on $S$, which we call the Fenchel-Nielsen Teichmüller space associated to the pair $(\…

Researchers solved a complex problem for a specific type of 4-manifolds.

Quantum complexity lowerbound proved using differential geometry.

Kahn and Markovic \cite{KahnMark} proved that the fundamental group of each closed hyperbolic three manifold contains a closed surface subgroup. One of the main ingredients in their proof is a theorem which states that an assignment of nearly real, complex Fenchel-Nielsen coordinates to the cuffs of a pants decompositi…

We generalise the Karrass-Pietrowski-Solitar and the Nielsen realisation theorems from the setting of free groups to that of free products. As a result, we obtain a fixed point theorem for finite groups of outer automorphisms acting on the relative free splitting complex of Handel--Mosher and on the outer space of a fr…

Paper proves polynomial equivalence of quantum complexity metrics.

In this paper we combine our recent work on regular globally hyperbolic maximal anti-de Sitter structures with the classical theory of globally hyperbolic maximal Cauchy-compact anti-de Sitter manifolds in order to define an augmented moduli space. Moreover, we introduce a coordinate system in this space that resembles…

We prove Nielsen realisation for finite subgroups of the groups of untwisted outer automorphisms of RAAGs in the following sense: given any graph $Γ$, and any finite group $G\leqslant \mathrm{U}^0(A_Γ) \leqslant \mathrm{Out}^0(A_Γ)$, we find a non-positively curved cube complex with fundamental group $A_Γ$ on which $G$…

We consider complex Fenchel-Nielsen coordinates on the quasi-Fuchsian space of punctured tori. These coordinates arise from a generalisation of Kra's plumbing construction and are related to earthquakes on Teichmueller space. They also allow us to interpolate between two coordinate systems on Teichmueller space, namely…

Defines Fenchel-Nielsen coordinates for SL(3,C) representations.

Criterion for realizing groups on Enriques manifolds.

Study strong Nielsen equivalence on punctured disc homeomorphisms.

Approximates call option prices for Barndorff-Nielsen and Shephard model.

Algorithm classifies surface homeomorphisms with polynomial time complexity.

Dehn twists on K3-type 4-manifolds are not homotopy coherently Nielsen realizable.

The paper counts mapping classes by Nielsen-Thurston type, finding growth rates for different subsets.

The paper generalizes Nielsen equivalence to 2-orbifolds.

Extends Alòs' formula to Barndorff-Nielsen and Shephard model.

Solves Nielsen realization problem for hyper-Kähler manifolds.

We prove that the Nielsen zeta function is a rational function or a radical of a rational function for orientation preserving homeomorphisms on closed orientable 3-dimensional manifolds which are special Haken or Seifert manifolds. In the case of pseudo-Anosov homeomorphism of surface we compute an asymptotic for the n…

Calculates twist in Teichmüller space using cross ratios.

The purpose of this expository paper is to present new directions in the classical Nielsen-Reidemeister fixed point theory. We describe twisted Burnside-Frobenius theorem, groups with $R_\infty$ \emph{property} and a connection between Nielsen fixed point theory and symplectic Floer homology.

We study Nielsen equivalence classes of generating pairs of Kleinian groups and HNN-extensions. We establish the following facts: - Hyperbolic 2-bridge knot groups have infinitely many Nielsen classes of generating pairs. - For any natural number N there is a closed hyperbolic 3-manifold whose fundamental group has N d…

Given two maps f1 and f2 from the sphere Sm to an n-manifold N, when are they loose, i.e. when can they be deformed away from one another? We study the geometry of their (generic) coincidence locus and its Nielsen decomposition. On the one hand the resulting bordism class of coincidence data and the corresponding Niels…

The main goal of this paper is to give the first examples of equivariant aspherical Poincare complexes, that are not realized by group actions on closed aspherical manifolds $M$. These will also provide new counterexamples to the Nielsen realization problem about lifting homotopy actions of finite groups to honest grou…

Nielsen reduction is an algorithm which decomposes any automorphism of a free group into a product of elementary Nielsen transformations. While this may be applied to a mapping class of a surface $S_{g,1}$ with one boundary component, the resulting decomposition in general will not have a topological interpretation. In…

Infinitely many unique ways to generate a surface's mapping class group.

The SL(2)-character variety X of a closed surface M enjoys a natural complex-symplectic structure invariant under the mapping class group G of M. Using the ergodicity of G on the SU(2)-character variety, we deduce that every G-invariant meromorphic function on X is constant. The trace functions of closed curves on M de…

We extend the Nielsen theory of coincidence sets to equalizer sets, the points where a given set of (more than 2) mappings agree. On manifolds, this theory is interesting only for maps between spaces of different dimension, and our results hold for sets of k maps on compact manifolds from dimension (k-1)n to dimension …

We show that the Nielsen number of a map is a knot invariant via representation variety

Abstract: Poisson bracket on shear coordinates relates to Fenchel-Nielsen bracket on gluing parameters.

The paper proves a theorem about fixed points and relates it to the Nielsen realisation problem.

The theorem connects surface mapping groups to fundamental groupoids.

The problem on the minimal number (with respect to deformation) of intersection points of two closed curves on a surface is solved. Following the Nielsen approach, we define classes of intersection points and essential classes of intersection points, which "are preserved under deformation" and whose total number is cal…

The paper consists of four parts. Part I presents a brief survey of the Nielsen fixed point theory. Part II deals with dynamical zeta functions connected with Nielsen fixed point theory. Part III is concerned with congruences for the Reidemeister and Nielsen numbers. Part IV deals with the Reidemeister torsion . In Cha…

The paper computes Fenchel-Nielsen coordinates for fixed points of cyclic actions on Teichmüller space.

We introduce Fenchel-Nielsen coordinates on Teicmüller spaces of surfaces of infinite type. The definition is relative to a given pair of pants decomposition of the surface. We start by establishing conditions under which any pair of pants decomposition on a hyperbolic surface of infinite type can be turned into a geom…

Study shows non-spin 4-manifolds where smooth Nielsen realization fails.

For each fixed n>=2 we show how the Nielsen-Thurston classification of mapping classes for a closed surface of genus g>=2 is determined by the sequence of quantum SU(n) representations, when one considers all levels. That this is the case is a consequence of our asymptotic faithfulness property. We here provide explici…

The paper removes a condition for the Nielsen realisation problem using equivariant Poincaré duality.

Topological proof of Weil-Petersson symplectic form using Fenchel-Nielsen coordinates.

Develops methods to simulate option prices for a specific stochastic volatility model.

Solves a problem related to Nielsen realization for certain groups.

The paper finds infinitely many 4-manifolds with non-isotopic sections.

We develop Fenchel-Nielsen coordinates for representations of surface groups into Sp(2n,R) with maximal Toledo invariant. Analogous to classical Fenchel-Nielsen coordinates on the Teichmüller space they consist of a parametrization of representations of the fundamental group of a pair of pants and a careful investigati…

Study shows Dehn twists on certain 4-manifolds cannot be realized by finite order diffeomorphisms.