Study shows virtually abelian subgroups have commensurable counterparts in mapping class groups.
problem Understanding virtually abelian subgroups in mapping class groups.
method Proving commensurability and normalizer relationships for virtually abelian subgroups.
result Upper bounds for geometric dimension of mapping class groups for abelian subgroups of bounded rank.
We characterise the virtually abelian groups which are fundamental groups of compact Kähler manifolds and of smooth projective varieties. We show that a virtually abelian group is Kähler if and only if it is projective. In particular, this allows to describe the Kähler condition for such groups in terms of integral sym…
A companion result of the the Tits alternative for Out(Fn) is proved: Every solvable subgroup of Out(Fn) is finitely generated and virtually abelian.
We show that a closed, connected, oriented, Riemannian n-manifold, admitting a branched cover of bounded length distortion from Rn, has a virtually Abelian fundamental group.
Geodesic loops escape from balls at a sublinear rate imply virtually abelian fundamental group.
problem Understanding fundamental groups of open manifolds with nonnegative Ricci curvature.
method Generalizing the Cheeger-Gromoll splitting theorem to sublinear escape rates.
result Fundamental groups of open manifolds with nonnegative Ricci curvature are virtually abelian if geodesic loops escape sublinearly.
New groups from strand diagrams show polycyclic subgroups are virtually abelian and undistorted.
problem Understanding the structure of mapping class groups.
method Introducing Chambord groups from braided strand diagrams and semigroup presentations.
result Polycyclic subgroups in Chambord groups are virtually abelian and undistorted.
A generalized Baumslag-Solitar group (GBS group) is a finitely generated group G which acts on a tree with all edge and vertex stabilizers infinite cyclic. We show that Out(G) either contains non-abelian free groups or is virtually nilpotent of class at most 2. It has torsion only at finitely many primes. One may dec…
Open manifolds with nonnegative Ricci curvature have virtually abelian fundamental groups if they escape from bounded balls at a small rate.
problem Understanding the fundamental groups of open manifolds with nonnegative Ricci curvature.
method Analyzing the escape rate of minimal geodesic loops and relating it to the fundamental group's properties.
result If an open manifold has a small escape rate, its fundamental group is virtually abelian.
The article calculates the minimal model dimensions for classifying spaces of surface braid groups.
problem Classifying spaces for families of virtually abelian subgroups of surface braid groups.
method Analyzes the pure and full braid groups of surfaces with at least one boundary component or one puncture, proving analogous results for amenable subgroups.
result Minimal dimensions of models for classifying spaces are equal to the virtual cohomological dimension plus the rank of virtually abelian subgroups.
Fukaya-Yamaguchi conjecture holds in 4D manifolds with nonnegative curvature.
problem Fundamental group of nonnegative curvature manifolds.
method Observation in dimension 4.
result Fukaya-Yamaguchi conjecture holds in 4D.
New invariants for virtual knots and links defined via quiver representations.
problem Defining new invariants for virtual knots and links.
method Quiver representations associated to virtual biquandles and rings.
result New polynomial invariants for virtual knots and links.
We show, using Wise's equitable sets criterion, that every tubular free by cyclic group acts freely on a CAT(0) cube complex. We also show that these groups have a finite index subgroup satisfying the strongest Tits alternative, which means that every subgroup either surjects a non abelian free group or is torsion free…
Controlled K-theory is used to show that algebraic K-theory of virtually abelian groups is described by an assembly map defined using possibly-infinite hyperelementary subgroups. The Farrell-Jones summand (coming from infinite subgroups) is parameterized by the rational projective space of the group, and a reduced …
The paper characterizes convex co-compact groups with one-dimensional boundary faces.
problem Characterizing convex co-compact groups with specific boundary properties.
method Proving relative hyperbolicity and using coarse Hilbert dimension.
result Convex co-compact groups with one-dimensional boundary faces are relatively hyperbolic.
Define quiver representation-valued invariants for classical and virtual knots
problem Define quiver representation-valued invariants for classical and virtual knots
method Define an infinite family of quiver representation-valued invariants of classical and virtual knots associated to a choice of data vector consisting of a biquandle, abelian group, set of biquandle arrows weights with values in the abelian group, coefficient ring and set of biquandle endomorphisms.
result Extract four new polynomial invariants as decategorifications
The paper solves the conjugacy problem in a specific braid group quotient and finds infinite virtually cyclic subgroups.
problem Solving the conjugacy problem in the Artin braid group quotient Bn/[Pn,Pn]. method Using systems of equations over the integers derived from the action of Bn/[Pn,Pn] on the abelianization of Pn/[Pn,Pn]. Also, explicitly realizing infinite virtually cyclic subgroups. result Explicitly realized infinite virtually cyclic subgroups in Bn/[Pn,Pn]. New knot invariants using biquandle fares.
problem Creating new knot invariants.
method Using biquandle fares to map paths in diagrams to abelian groups.
result Proper enhancements of invariants for oriented knots and links.
We consider linear groups which do not contain unipotent elements of infinite order, which includes all linear groups in positive characteristic, and show that this class of groups has good properties which resemble those held by groups of non positive curvature and which do not hold for arbitrary characteristic zero l…
Unified algebraic framework for virtual braid structures with strong structural consequences.
problem Unified algebraic framework for virtual braid structures with various types of crossings.
method Introducing the universal virtual braid group UVn(c) and proving its properties. result Strong structural consequences including residual finiteness, linearity, and solvability of conjugacy problems.
We show that if a group is not virtually cyclic and is hyperbolic relative to a family of proper subgroups, then it has a hyperbolically embedded subgroup which contains a finitely generated non-abelian free group as a finite index subgroup.
Study of permutational wreath pullbacks and their properties.
problem Structural study of permutational wreath pullbacks and their properties.
method Systematic structural study of permutational wreath pullbacks, focusing on center, abelianization, and functorial behavior.
result Established a criterion for the abelian kernel to be characteristic and for the wreath product to inherit the R-infinity property.
We show that any Kahler extension of a finitely generated abelian group by a surface group of genus g at least 2 is virtually a product. Conversely, we prove that any homomorphism of an even rank, finitely generated abelian group into the genus g mapping class group with finite image gives rise to a Kahler extension. T…
Given a probability measure on a finitely generated group, its Martin boundary is a way to compactify the group using the Green's function of the corresponding random walk. We give a complete topological characterization of the Martin boundary of finitely supported random walks on relatively hyperbolic groups with virt…
This paper calculates the geometric dimension for 3-manifold groups up to n=2.
problem Computing the geometric dimension for 3-manifold groups.
method Analyzing families of subgroups containing virtually abelian subgroups.
result Computed the geometric dimension for 3-manifold groups for all n ≥ 2.
This paper gives the first example of a unipotent group that is not virtually abelian and preserves a strictly convex domain.
Open manifolds with nonnegative Ricci curvature and Euclidean volume growth have finitely generated fundamental groups.
problem Understanding fundamental groups of open manifolds with specific curvature properties.
method Analyzing universal covers with Euclidean volume growth and applying topological group theory.
result Fundamental groups are finitely generated and virtually abelian under given conditions.
In the study of discontinuous groups for non-Riemannian homogeneous spaces, the idea of "continuous analogue" gives a powerful method (T. Kobayashi [Math. Ann. 1989]). For example, a semisimple symmetric space G/H admits a discontinuous group which is not virtually abelian if and only if G/H admits a proper SL(2,R)-act…
New examples show non-abelian fundamental groups for positive Ricci curvature manifolds.
problem Constructing manifolds with positive Ricci curvature and non-abelian fundamental groups.
method Constructing specific 9-dimensional manifolds with positive Ricci curvature and non-uniformly virtually abelian fundamental groups.
result Examples of manifolds with positive Ricci curvature and non-uniformly virtually abelian fundamental groups.
A virtual Schottky group is a Kleinian group K containing a Schottky group G as a finite index normal subgroup. These groups correspond to those groups of automorphisms of closed Riemann surfaces which can be realized at the level of their Schottky uniformizations. In this paper we provides a geometrical structural…
Suppose X and Y are compact connected topological 4-manifolds with fundamental group π. For any r⩾0, Y is r-stably homeomorphic to X if Y#r(S2×S2) is homeomorphic to X#r(S2×S2). How close is stable homeomorphism to homeomorphism? When the common fundamental group π i…
Study on virtual singular braid groups with algebraic properties and homomorphisms.
problem Algebraic properties and homomorphisms of virtual singular braid groups.
method Numerical invariants, homomorphisms, semi-direct product decompositions, presentations, and quotients.
result Determined all group homomorphisms from VSGn to Sn and obtained corresponding semi-direct product decompositions. In recent years, the RFRS condition has been used to analyze virtual fibering in 3-manifold topology. Agol's work shows that any 3-manifold with zero Euler characteristic satisfying the RFRS condition on its fundamental group virtually fibers over the circle. In this note we will show that a finitely generated nilpoten…
For certain manifolds, nonnegative Ricci curvature limits dimension and forces almost abelian fundamental group.
problem Bounding the dimension of manifolds with nonnegative Ricci curvature and specific fundamental group properties.
method Dimensional estimates for RCD(0,N) spaces with large Hausdorff dimension. result If dimension is less than 12, the fundamental group is almost abelian.
The study shows how nonnegative Ricci curvature and metric cones imply the existence of abelian subgroups in the fundamental group of open manifolds.
problem Understanding the structure of fundamental groups of open manifolds with specific curvature properties.
method Analyzing the properties of the Riemannian universal cover and its asymptotic cones.
result The fundamental group of an open manifold with nonnegative Ricci curvature and certain geometric properties contains an abelian subgroup of finite index.
New knot invariants derived from biquandle quivers.
problem Enhancing knot invariants for virtual and classical knots.
method Categorification using biquandle coloring quivers.
result New infinite families of polynomial invariants.
Proves conditions for nearby special Lagrangians in Calabi-Yau manifolds.
problem Conditions for nearby special Lagrangians in Calabi-Yau manifolds.
method Analyzes fundamental group, Floer cohomology, and special Lagrangian conditions.
result Conditions for nearby special Lagrangians in Calabi-Yau manifolds.
Study shows how to embed any group into the first homology of a 3-manifold cover.
problem Embedding finite abelian groups into the first homology of 3-manifold covers.
method Proves existence of finite covers with prescribed torsion.
result Any finite abelian group can be a direct factor in the first homology of a 3-manifold cover.
In this paper, we will use Kahn-Markovic's almost totally geodesic surfaces to construct certain π1-injective 2-complexes in closed hyperbolic 3-manifolds. Such 2-complexes are locally almost totally geodesic except along a 1-dimensional subcomplex. Using Agol and Wise's result that fundamental groups of hyperbolic …
The study shows that certain groups can be uniquely identified by their finite abelian summands.
problem Identifying groups based on their finite abelian summands.
method Analyzing hyperbolic groups as graphs of free groups with cyclic edge groups.
result Free products of free and surface groups are profinitely rigid.
Consider a group G and a family A of subgroups of G. We say that vertex finiteness holds for splittings of G over A if, up to isomorphism, there are only finitely many possibilities for vertex stabilizers of minimal G-trees with edge stabilizers in A. We show vertex finiteness when G…
Extends confining subset theory to describe hyperbolic actions of solvable groups with higher rank abelianizations.
problem Describing hyperbolic actions of solvable groups with higher rank abelianizations.
method Extends confining subset theory to apply to solvable groups with higher rank abelianizations.
result Complete description of hyperbolic actions of generalized solvable Baumslag-Solitar groups.
We prove that all elements of infinite order in Out(Fn) have positive translation lengths; moreover, they are bounded away from zero. Consequences include a new proof that solvable subgroups of Out(Fn) are finitely generated and virtually abelian and the new result that such subgroups are quasi-convex.
Study of group orderability using tensor and exterior squares.
problem Circular orderability of groups and torsion elements.
method Analysis of tensor and exterior squares of groups.
result Circularly orderable groups have left-orderable tensor and exterior squares under certain conditions.
Proposes categorification of Z-invariants for specific 3-manifolds.
problem Categorification of Z-invariants for negative definite plumbed 3-manifolds.
method Abelian categorification using 3d N=2 theory and log VOAs.
result Nested Weyl-type character formulas reconstruct Z^-invariants. New invariants defined for knots and links using quandle representations.
problem Defining new invariants for knots and links.
method Defined a family of quiver representations associated to finite quandles, abelian groups, and quandle 2-cocycles.
result Computed four new polynomial invariants for knots and links.
Classifies algebraic concordance for almost classical knots.
problem Classifying algebraic concordance for almost classical knots.
method Defined virtual algebraic concordance group for almost classical knots.
result Embeds GQ into VGQ and contains non-classical finite-order elements. Let F be a finite group with a Sylow 2-subgroup S that is normal and abelian. Using hyperelementary induction and cartesian squares, we prove that Cappell's unitary nilpotent groups UNil_*(Z[F];Z[F],Z[F]) have an induced isomorphism to the quotient of UNil_*(Z[S];Z[S],Z[S]) by the action of the group F/S. In particular…
Study covers of Chamanara surface with large Veech groups.
problem Characterize finite abelian covers with large Veech groups.
method Analyze Veech groups of finite abelian covers of the Chamanara surface.
result Every free group arises as the projective Veech group of a finite-area infinite translation surface.