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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.

168,742 papers · 148 categories

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70141211281 · May 202619922001200920172026
48 results for uniformly contractible manifolds

The paper proves scalar curvature decay for uniformly contractible manifolds with finite asymptotic dimension.

problem Proving decay of scalar curvature for uniformly contractible manifolds with finite asymptotic dimension.
method Using index pairing between Dirac operators and compactly supported vector bundles with Lipschitz control, and Lipschitz control for topological K-theory of finite dimensional simplicial complexes.
result The scalar curvature decays to zero at a rate depending only on the contractibility radius and the diameter control of the asymptotic dimension.

Whenever a finitely generated group GG acts properly discontinuously by isometries on a metric space XX, there is an induced uniform embedding (a Lipschitz and uniformly proper map) ρ:GXρ: G \rightarrow X given by mapping GG to an orbit. We study when there is a difference between a finitely generated group GG acting…

2019-03-08abs ↗pdf ↗

We show that a space with a finite asymptotic dimension is embeddable in a non-positively curved manifold. Then we prove that if a uniformly contractible manifold X is uniformly embeddable in Rn\R^n or non-positively curved n-dimensional simply connected manifold then X×RnX\times\R^n is integrally hyperspherical. If a un…

1999-12-08abs ↗pdf ↗

Uniformly extend maps on Hadamard manifolds with curvature constraints.

problem Extending maps on Hadamard manifolds with curvature constraints.
method Proving uniform extension for contracting maps on Hadamard manifolds with curvature bounds.
result Uniform Lipschitz extension achieved for contracting maps on Hadamard manifolds with curvature constraints.

This paper examines limits of Riemannian 2-manifolds with bounded curvature.

problem Understanding the limits of Riemannian 2-manifolds with bounded curvature.
method Uniform semi-locally 1-connected sequences of closed connected Riemannian 2-manifolds with bounded total absolute curvature.
result Description of Gromov-Hausdorff limits of the sequences.

No 5D aspherical manifolds can have uniformly positive scalar curvature.

problem Proving the non-existence of metrics with positive scalar curvature on certain 5D manifolds.
method Uniform acyclicity and toric symmetrization of stable μ-bubbles.
result Compact aspherical 5-manifolds cannot have metrics with uniformly positive scalar curvature.

Curvature conditions distinguish Euclidean space and disks in contractible manifolds.

problem Distinguish Euclidean space and disks among contractible manifolds.
method Investigate curvature conditions on open and compact contractible manifolds with boundary.
result Stronger curvature conditions can distinguish disks from Euclidean spaces.

Study finds topological restrictions on 4-manifolds with uniformly positive scalar curvature.

problem Understanding which 4-manifolds can have metrics with uniformly positive scalar curvature.
method Topological obstructions and metric constructions on specific 4-manifolds.
result Existence of uncountably many exotic R4\mathbb{R}^4's without such metrics and topological uniqueness of certain metrics.

We consider compact convex hypersurfaces contracting by functions of their curvature. Under the mean curvature flow, uniformly convex smooth initial hypersurfaces evolve to remain smooth and uniformly convex, and contract to points after finite time. The same holds if the initial data is only weakly convex or non-smoot…

2011-04-05abs ↗pdf ↗

We show that an enlargeable Riemannian metric on a (possibly nonspin) manifold cannot have uniformly positive scalar curvature. This extends a well-known result of Gromov and Lawson to the nonspin setting. We also prove that every noncompact manifold admits a nonenlargeable metric. In proving the first result, we use t…

2018-10-04abs ↗pdf ↗

This paper proves properties of uniformly hyperbolic sets and constructs Markov partitions.

problem Establishing properties of uniformly hyperbolic sets and constructing Markov partitions.
method Backward graph transform, spectral decomposition, shadowing lemma, Markov partitions construction.
result Explicit bounds and Hölder continuity for the coding map.

We prove that convex hypersurfaces in Rn+1{\mathbb R}^{n+1} contracting under the flow by any power α>1n+2α>\frac{1}{n+2} of the Gauss curvature converge (after rescaling to fixed volume) to a limit which is a smooth, uniformly convex self-similar contracting solution of the flow. Under additional central symmetry of the ini…

2015-10-02abs ↗pdf ↗

We complete the proof of the Generalized Smale Conjecture, apart from the case of RP3RP^3, and give a new proof of Gabai's theorem for hyperbolic 3-manifolds. We use an approach based on Ricci flow through singularities, which applies uniformly to spherical space forms other than S3S^3 and RP3RP^3 and hyperbolic manifold…

2017-12-17abs ↗pdf ↗

We develop some basic Lipschitz homotopy technique and apply it to manifolds with finite asymptotic dimension. In particular we show that the Higson compactification of a uniformly contractible manifold is mod pp acyclic in the finite dimensional case. Then we give an alternative proof of the Higher Signature Novikov …

2001-02-19abs ↗pdf ↗

Study on singularities of solutions to Hamilton-Jacobi equations on manifolds.

problem Characterizing singularities of solutions to time-dependent Hamilton-Jacobi equations.
method Uniformly continuous viscosity solutions, Tonelli Hamiltonians, homotopy theory.
result The set of points where solutions are not differentiable is locally contractible.

Study of Brown--York mass for four-dimensional asymptotically flat manifolds.

problem Calculating mass for hypersurfaces in four-dimensional asymptotically flat manifolds.
method Intrinsic definition of mean curvature, expansion analysis for large uniformly convex hypersurfaces.
result Shape-dependent correction to ADM mass for nearly round surfaces vanishes under certain conditions.

The paper analyzes game theory in convertible contracts during liquidity events.

problem Optimizing payments in convertible contracts during liquidity events.
method Defined a general model for games, showed non-existence of pure strategy Nash equilibria, developed algorithms for computing equilibria.
result Optimum pure strategy Nash equilibria exist when all contracts are of the same type (SAFE).

In the paper portfolio optimization over long run risk sensitive criterion is considered. It is assumed that economic factors which stimulate asset prices are ergodic but non necessarily uniformly ergodic. Solution to suitable Bellman equation using local span contraction with weighted norms is shown. The form of optim…

2015-08-22abs ↗pdf ↗

We construct a compact metric space that has any other compact metric space as a tangent, with respect to the Gromov-Hausdorff distance, at all points. Furthermore, we give examples of compact sets in the Euclidean unit cube, that have almost any other compact set of the cube as a tangent at all points or just in a den…

2014-06-30abs ↗pdf ↗

One can define what it means for a compact manifold with corners to be a "contractible manifold with contractible faces." Two combinatorially equivalent, contractible manifolds with contractible faces are diffeomorphic if and only if their 4-dimensional faces are diffeomorphic. It follows that two simple convex polytop…

2013-06-25abs ↗pdf ↗

The paper studies circle packings using renormalization and subdivision rules.

problem Characterizing and proving properties of circle packings with specific subdivision rules.
method Iterations of skinning maps on Teichmüller spaces, renormalization theory, subdivision rules.
result Uniformly contracting renormalization operator and geometric inflexibility of circle packings.

Proposes a new generalization bound for Bayesian deep nets without strict assumptions.

problem Lack of generalization bounds for Bayesian deep nets without strict assumptions.
method Exploits contractivity of Log-Sobolev inequalities to add a loss-gradient norm term to the generalization bound.
result Introduces a new generalization bound for Bayesian deep nets that avoids strict assumptions.

Homotopy equivalence shown between complex and thickened versions of manifolds.

problem Homotopy equivalence between manifold complexes and thickened versions.
method Natural bijections and homotopy equivalences of Vietoris-Rips and Čech complexes and thickened versions.
result Natural bijections between complexes and thickened versions are homotopy equivalences.

Classifies 3-manifolds with uniformly positive scalar curvature.

problem Classifying 3-manifolds with uniformly positive scalar curvature.
method Analyzes properties of 3-manifolds with mean convex boundaries and uniformly positive scalar curvature.
result 3-manifolds with uniformly positive scalar curvature are homeomorphic to sums of spherical 3-manifolds and S1imesS2\mathbb{S}^1 imes \mathbb{S}^2.

Establishes exponential contraction in Wasserstein distance on manifolds and flows.

problem Analyzing contraction rates in Wasserstein distance on manifolds and their evolution.
method Explicit estimates and extension to evolving manifolds under geometric flow.
result Gradient estimates with exponential contraction rate under weak curvature conditions.

Exotic diffeomorphism survives stabilizations on a contractible 4-manifold.

problem Finding exotic diffeomorphisms on contractible 4-manifolds.
method Developed a Pin(2) × Z_2-equivariant refinement for computing Seiberg-Witten Floer homotopy types.
result Constructed an exotic diffeomorphism that survives two stabilizations.

Study shows how discrete graph curvature relates to manifold curvature.

problem Relating discrete graph curvature to intrinsic manifold curvature.
method Continuum limits of Ollivier's Ricci curvature on data clouds.
result Random geometric graphs inherit global curvature properties of manifolds.

We prove that the restricted holonomy group of a complete smooth solution to the Ricci flow of uniformly bounded curvature cannot spontaneously contract in finite time; it follows, then, from an earlier result of Hamilton that the holonomy group is exactly preserved by the equation. In particular, a solution to the Ric…

2011-05-18abs ↗pdf ↗

Transformer pretraining yields strong EB performance without explicit adaptation.

problem Empirical Bayes problems with unknown test distributions.
method Indirect analysis of pretrained transformer's performance under universal priors.
result Near-optimal regret bound of O~(1n)\widetilde{O}(\frac{1}{n}) for arbitrary test distributions.

Lickorish has constructed large families of contractible 4--manifolds that have knotted embeddings in the 4--sphere and has also shown that every finitely presented perfect group with balanced presentation occurs as the fundamental group of the complement of a knotted contractible manifold. Here we make a few observati…

2001-11-06abs ↗pdf ↗

The paper constructs contractible manifolds with knotted spheres.

problem Creating contractible manifolds with non-standard boundaries.
method Using handles and constructing knotted spheres in SnimesS2S^n imes S^2.
result Contractible (n+3)(n+3)-manifolds with non-standard boundaries are constructed.

Examples are given to show that some compact contractible 4-manifolds can be knotted in the 4-sphere. It is then proved that any finitely presented perfect group with a balanced presentation is a knot group for an embedding of some contractible 4-manifold in the 4-sphere.

2001-07-31abs ↗pdf ↗

Study of contractible manifolds and their twists to determine if they are S4S^4.

problem Determine if a specific manifold is S4S^4 using twists and handlebody descriptions.
method Analyze two contractible manifolds, one Stein and one non-Stein, with non-trivial boundary mapping classes. Use a specific homotopy sphere to test if it is S4S^4.
result Show that a specific manifold is indeed S4S^4.

Paper tackles which 3-spheres bound contractible 4-manifolds or homology 4-balls.

problem Which homology 3-spheres bound contractible 4-manifolds or homology 4-balls?
method Addressed using plumbed 3-manifolds, modified Mazur's argument, and worked with Poénaru manifolds.
result Presented two new infinite families of plumbed 3-manifolds that bound contractible 4-manifolds or homology 4-balls.