New spines found in complex 4D shapes.
problem Finding spines in complex 4D shapes.
method Examined Levine and Lidman's constructions and found new spines.
result Infinitely many 4-manifolds have topological spines.
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48 results for “topological spines”
The Thurston spine's properties are studied in relation to Morse-Smale complexes.
problem Understanding the Thurston spine's local properties and their global implications.
method Analyzes the Thurston spine as a subset of Teichmüller space and studies its local properties in relation to the systole function.
result The Thurston spine satisfies properties analogous to Morse-Smale complexes, demonstrating its topological significance.
Continuum-wise hyperbolicity is exactly the pseudo-Anosov dynamics with spine singularities.
problem Classification of continuum-wise hyperbolic surface homeomorphisms
method Proving a complete structural classification
result Every cw-hyperbolic homeomorphism is pseudo-Anosov with spine singularities
The paper shows conditions under which certain 4-manifolds have no smooth spines.
problem Conditions for 4-manifolds to have no smooth spines.
method Using Heegaard Floer homology and high-dimensional surgery theory, the paper identifies obstructions for 4-manifolds to have smooth spines.
result The paper proves that certain knots and 4-manifolds do not have smooth spines.
Outer space and Teichmüller space fail well-rounded retract analogy.
problem Failure of well-rounded retract in Outer space and Teichmüller space.
method Analysed flat tori and metric graphs to show failure.
result Analogue of well-rounded retract does not contain equivariant spine.
A celebrated result concerning triangulations of a given closed 3-manifold is that any two triangulations with the same number of vertices are connected by a sequence of so-called 2-3 and 3-2 moves. A similar result is known for ideal triangulations of topologically finite non-compact 3-manifolds. These results build o…
Paper proves unique contact structure supported by positive flow-spines.
problem Existence and uniqueness of contact structures on 3-manifolds.
method Introduces positivity condition for flow-spines and proves existence and uniqueness of contact structures.
result Any positive flow-spine of a closed, connected, oriented 3-manifold supports a unique contact structure up to isotopy.
Nonpositive towers property in 3-manifolds spines.
problem Properties of 3-manifold spines.
method Analysis of 2-dimensional spines in aspherical 3-manifolds and 3-ball.
result Nonpositive towers property in 2-dimensional spines of aspherical 3-manifolds.
Spines of minimal lengthmath.GT
In this paper we raise the question whether every closed Riemannian manifold has a spine of minimal area, and we answer it affirmatively in the surface case. On constant curvature surfaces we introduce the spine systole, a continuous real function on moduli space that measures the minimal length of a spine in each surf…
Unique simple spines of homotopy 2-spheres are shown to be ambiently isotopic.
problem Characterizing and comparing simple spines of homotopy 2-spheres.
method Proving ambient isotopy of simple spines representing the same homology class.
result Simple spines of homotopy 2-spheres are unique.
Bing's house-like spines approximate all PL manifolds.
problem Understanding spines of PL manifolds.
method Approximation rigidity and h-principle.
result PL manifolds have spines similar to Bing's house.
Corrects a 1-off error in Harer's spine dimension calculation for decorated Teichmüller spaces.
problem Incorrect dimension calculation in Harer's spine for decorated Teichmüller spaces.
method Identifies and corrects the dimension discrepancy in Harer's spine construction.
result Corrects the dimension of Harer's spine by 1 for decorated Teichmüller spaces.
Constructs Teichmüller curve to study Thurston spine structure.
problem Understanding the structure of Thurston spine in Teichmüller space.
method Constructs a Teichmüller curve and characterizes its intersection with Thurston spine.
result Characterizes Thurston spine as a trivalent tree and equivariant deformation retract of Teichmüller curve.
This paper proves a map from flow-spines to contact structures is surjective.
problem Mapping flow-spines to contact structures in 3-manifolds.
method Using positive flow-spines and contact structures, proving surjectivity.
result The map from flow-spines to contact structures is surjective.
In this article we establish the relation between the spines of 3-manifolds and the polyhedra with identified faces. We do this by showing that the spines of the closed, connected, orientable 3-manifolds can be presented through polyhedra with identified faces in a very natural way. We also prove the equivalence betwee…
A special spine of a three-manifold is said to be poor if it does not contain proper simple subpolyhedra. Using the Turaev-Viro invariants, we establish that every compact three-dimensional manifold M with connected nonempty boundary has a finite number of poor special spines. Moreover, all poor special spines of the m…
Knotted trivalent graphs (KTGs) form a rich algebra with a few simple operations: connected sum, unzip, and bubbling. With these operations, KTGs are generated by the unknotted tetrahedron and Moebius strips. Many previously known representations of knots, including knot diagrams and non-associative tangles, can be tur…
The abstract extends Reidemeister theorem to 3-manifolds using diagrams of links and bands.
problem Extending Reidemeister theorem to 3-manifolds.
method Defines diagrams for links and bands on spines and flow-spines of 3-manifolds and describes combinatorial moves.
result Reproves and extends Brand et al. result on 3-manifolds.
Spatial Cube Complexesmath.GR
New geometric spine for Artin groups defined by cube complexes.
problem Geometric characterization of Artin group spines.
method Category of spatial cube complexes for geometric simplicial complex.
result Realized spine as natural simplicial complex.
Paper shows mapping class group-equivariant Teichmüller space deformation to Thurston spine.
problem Mapping Teichmüller space to Thurston spine.
method Equivariant deformation retraction of Teichmüller space onto a cell complex.
result Thurston spine contains points corresponding to hyperbolic surfaces with shortest geodesics forming polygons.
Thurston's spine dimension exceeds virtual cohomological dimension.
problem Understanding the dimension of Thurston's spine in moduli space.
method Analyzing closed hyperbolic surfaces and their systoles.
result The dimension of the set of surfaces is at least \(5-\varepsilon\) for large genus.
A spine is constructed for a non-orientable surface's decorated Teichmüller space.
problem Constructing a spine for a non-orientable surface's decorated Teichmüller space.
method Building on Harer's work, constructing a spine and computing its dimension, showing equivariance with the pure mapping class group.
result A spine is constructed with minimal dimension for a punctured non-orientable surface.
New 3-manifold spines with unique Whitehead graphs identified.
problem Identifying new 3-manifold spines with specific Whitehead graph types.
method Cyclic presentations and conditions on parameters to show spines of 3-manifolds.
result Examples of 3-manifolds with Whitehead graphs of specific types.
Study filling links in 3-manifolds to understand their topological properties.
problem Understanding the topological properties of 3-manifolds through filling links.
method Introduce and study filling links, prove their existence and injectivity properties.
result Existence of k-filling links in the 3-torus for each k>1.
Theory of link projections to 3-manifold spines, proving combinatorial moves for isotopic links.
problem Link equivalence on 3-manifold spines.
method Theory of link projections, combinatorial moves, Reidemeister Theorem.
result Crossingless projections and combinatorial moves for isotopic links.
Tico Spinesmath.GT
Any bounding compact smooth manifold bounds a compact manifold with a spine consisting of transversely intersecting codimension one submanifolds. This paper provides details for a picture proof given in previous papers with S. Akbulut.
Simplified combinatorial descriptions of branched spines for 3-manifolds using primary MP move and sliding moves.
problem Combinatorial descriptions of branched spines for 3-manifolds and their equivalence relations.
method Demonstrated that 16 MP moves on branched spines are derived from a primary MP move, pure sliding moves, and their inverses.
result Simpler combinatorial descriptions for closed 3-manifolds and combed 3-manifolds.
In math.GT/0106017 it was shown that thin position on Heegaard spines can be a useful tool for analyzing the topology of knots in 3-space. The proof there (specifically, of the Goda-Teragaito conjecture) requires masses of technical detail; it is easy to lose track of the underlying ideas. The present paper gives an ov…
Geometrical spines are defined for 3-manifolds with natural metrics, in particular, for lens manifolds. We show that any spine of L(p,q) close enough to its geometrical spine (i.e., to the cut locus with respect to the standard metric) contains at least E(p,q)-3 vertices, which is exactly the conjectured value for Matv…
-stratifolds are a generalization of -manifolds in that there are disjoint simple closed branch curves. We obtain a list of all closed -manifolds that have a -stratifold as a spine.
Equivariant trisections for group actions on 4-manifolds are introduced and studied.
problem Understanding the equivariant topology of -manifolds and their quotients.
method Introducing -equivariant trisections and bridge trisections, and establishing their existence for -manifolds.
result Any -manifold admits a -equivariant trisection such that a -invariant surface is in equivariant bridge trisection position.
New proof confirms surfaces can be divided into polygons.
problem Estimating the dimension of Thurston spine.
method Existence of an infinite set A, proving codimension is o(g/ log g).
result Proves recent conjecture about Thurston spine dimension.
We establish a calculus for branched spines of 3-manifolds by means of branched Matveev-Piergallini moves and branched bubble-moves. We briefly indicate some of its possible applications in the study and definition of State-Sum Quantum Invariants.
We provide combinatorial realizations, according to the usual objects/moves scheme, of the following three topological categories: (1) pairs (M,v) where M is a 3-manifold (up to diffeomorphism) and v is a (non-singular vector) field, up to homotopy; here possibly the boundary of M is non-empty and v may be tangent to t…
New applications of trace embedding lemma show exotic 4-manifolds properties.
problem Detecting exotic phenomena in 4-dimensional smooth structures.
method New applications of trace embedding lemma to study piecewise-linear surfaces.
result Found infinitely many pairs of homeomorphic 4-manifolds with distinct properties.
We introduce and analyze the characteristic foliation induced by a contact structure on a branched surface, in particular a branched standard spine of a 3-manifold. We extend to (fairly general) singular foliations of branched surfaces the local existence and uniqueness results which hold for genuine surfaces. Moreover…
Properly immersed curves in arbitrary surfaces via apparent contours on spines of traversing flowsmath.GT
The paper studies curves in surfaces using flow-spines and apparent contours.
problem Understanding curves in arbitrary surfaces using flow-spines and apparent contours.
method By considering generic curves and their apparent contours relative to a traversing flow, the paper reconstructs curves and allows them to vary up to homotopy.
result A finite set of local moves on decorated graphs allows for the reconstruction and variation of curves within a fixed generic flow.
New contractible complex shows virtual cohomological dimension of RAAGs.
problem Determining virtual cohomological dimension of RAAGs.
method Equivariant deformation retraction of spine to contractible cube complex.
result Dimension of new complex realises virtual cohomological dimension of RAAGs.
For a 3-dimensional manifold , its complexity , introduced by S.Matveev, is the minimal number of vertices of an almost simple spine of ; in many cases it is equal to the minimal number of tetrahedra in a singular triangulation of . An approach to estimating from below for total spaces o…
We show that under reasonable conditions, the spines of the handlebodies of a strongly irreducible Heegaard splitting will intersect a closed ball in a graph which is isotopic into the boundary of the ball. This is in some sense a generalization of the results by Scharlemann on how a strongly irreducible Heegaard split…
We introduce a novel approach for predicting the progression of adolescent idiopathic scoliosis from 3D spine models reconstructed from biplanar X-ray images. Recent progress in machine learning have allowed to improve classification and prognosis rates, but lack a probabilistic framework to measure uncertainty in the …
We construct infinitely many smooth 4-manifolds which are homotopy equivalent to but do not admit a spine, i.e., a piecewise-linear embedding of which realizes the homotopy equivalence. This is the remaining case in the existence problem for codimension-2 spines in simply-connected manifolds. The obstructio…
Outer space and finiteness properties for symmetric automorphisms of RAAGs, and generalisationsmath.GR
Study on symmetric automorphisms of RAAGs, proving finiteness properties and contractibility.
problem Finiteness properties and contractibility of symmetric automorphisms of RAAGs.
method Definition of symmetric automorphism group, construction of symmetric Outer space, proof of contractibility.
result Finiteness properties and contractibility results for symmetric automorphisms of RAAGs.
We prove that for any contact 3-manifold supported by a spinal open book decomposition with planar pages, there is a universal bound on the Euler characteristic and signature of its minimal symplectic fillings. The proof is an application of the spine removal surgery operation recently introduced in joint work of the a…
Paper proves S-stability of foliations on flow-spines with transverse Reeb flow.
problem Characterizing S-stable foliations on flow-spines with transverse Reeb flow.
method Introduced S-stability for foliations on branched simple polyhedrons and proved stability for 1-forms with .
result Proved the number of simple tangency points of an S-stable foliation on a flow-spine is at least 2.
A canal surface is the envelope of a moving sphere with varying radius, defined by the trajectory C(t) (spine curve) of its center and a radius function r(t). In this paper, we investigate when parameter curves of the canal surface are also lines of curvature. Last of all, for special spine curves we obtain the radius …
The spine which was no spinemath.GT
Let T_n be the Teichmueller space of flat metrics on the n-dimensional torus and identify SL(n,Z) with the corresponding mapping class group. We prove that the subset Y consisting of those points at which the systoles generate the fundamental group of the torus is, for n > 4, not contractible. In particular, Y is not a…
New analysis of crushing surfaces of positive genus impacts triangulation complexity.
problem Crushing surfaces of positive genus can drastically change triangulation topology.
method Detailed analysis of crushing effects on closed essential surfaces of positive genus.
result Proved results about triangulation complexity and JSJ decompositions.