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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.

169,341 papers · 148 categories

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6491,2971,9462,594 · Jun 202019922001200920182026
48 results for curves of constant width

Flow deforms locally convex curves to curves of constant k-order width.

problem Evolve locally convex curves to curves of constant k-order width.
method Introduced a nonlocal curvature flow to evolve locally convex curves in the plane.
result The flow converges to a smooth, locally convex curve of constant k-order width as time goes to infinity.

In this paper we study properties of the area evolute (AE) and the center symmetry set (CSS) of a convex planar curve γγ. The main tool is to define a Minkowski plane where γγ becomes a constant width curve. In this Minkowski plane, the CSS is the evolute of γγ and the AE is an involute of the CSS. We prove that the…

2013-01-27abs ↗pdf ↗

Given a Riemannian metric on a homotopy nn-sphere, sweep it out by a continuous one-parameter family of closed curves starting and ending at point curves. Pull the sweepout tight by, in a continuous way, pulling each curve as tight as possible yet preserving the sweepout. We show: Each curve in the tightened sweepout …

2007-05-25abs ↗pdf ↗

The paper introduces new measures for ovals and finds geometric relations between their properties.

problem Understanding the properties of ovals and their measures.
method Introducing new measures (Constant Width Measure Set, Spherical Measure Set) and studying their geometrical properties.
result Exact relations between the length, area, and oriented areas of ovals and their measures.

A number of results for C2^2-smooth surfaces of constant width in Euclidean 3-space E3{\mathbb{E}}^3 are obtained. In particular, an integral inequality for constant width surfaces is established. This is used to prove that the ratio of volume to cubed width of a constant width surface is reduced by shrinking it along…

2007-04-24abs ↗pdf ↗

We give a simple procedure to estimate the smallest Lipshitz constant of a degree 1 map from a Riemannian 2-sphere to the unit 2-sphere, up to a factor of 10. Using this procedure, we are able to prove several inequalities involving this Lipshitz constant. For instance, if the smallest Lipshitz constant is at least 1, …

2005-01-02abs ↗pdf ↗

For negatively curved manifolds, a condition is found for intrinsic ultracontractivity of heat semigroups.

problem Investigating intrinsic ultracontractivity for domains in negatively curved manifolds.
method Using volume doubling property, Poincaré inequality, and Li-Yau Gaussian estimate for the Dirichlet heat kernel.
result The reciprocal of the bottom of the spectrum and the supremum of the torsion function are comparable with the square of the capacitary width for small capacitary width.

We present an alternative proof of the following fact: the hyperspace of compact closed subsets of constant width in Rn\mathbb R^n is a contractible Hilbert cube manifold. The proof also works for certain subspaces of compact convex sets of constant width as well as for the pairs of compact convex sets of constant rela…

2004-01-07abs ↗pdf ↗

In 1926 S. Nakajima (= A. Matsumura) showed that any convex body in R3\R^3 with constant width, constant brightness, and boundary of class C2C^2 is a ball. We show that the regularity assumption on the boundary is unnecessary, so that balls are the only convex bodies of constant width and brightness.

2003-06-30abs ↗pdf ↗

Let n be a natural number equal or greater than 2. In this paper we study the topological structure of certain hyperspaces of convex subsets of constant width, equipped with the Hausdorff metric topology. We focus our attention on the hyperspace cw_D(R^n) of all compact convex subsets with constant width d\in D, where …

2013-12-15abs ↗pdf ↗

Motivated by the theory of quantum waveguides, we investigate the spectrum of the Laplacian, subject to Dirichlet boundary conditions, in a curved strip of constant width that is defined as a tubular neighbourhood of an infinite curve in a two-dimensional Riemannian manifold. Under the assumption that the strip is asym…

2002-04-26abs ↗pdf ↗

Study on spherical bodies of constant width on the unit sphere, proving bounds on their relative effective radius.

problem Understanding the smallest spherical bodies of constant width on the unit sphere.
method Analyzing spherical bodies of constant width on the unit sphere, constructing examples and applying geometric arguments.
result Proved non-trivial bounds on the relative effective radius of spherical bodies of constant width.

The paper finds lower bounds on curve length with constraints on width and inradius.

problem Finding lower bounds on the length of space curves with constraints on width and inradius.
method Topological and integral geometric techniques, including Borsuk-Ulam theorem and Crofton's formulas.
result Estimates confirm some conjectures of Zalgaller up to 99% of their stated value and disprove one.

The paper bounds the min-max width of embedded circles on spheres and manifolds.

problem Bounding the min-max width of embedded circles on spheres and manifolds.
method Inducing a sweepout by pairs of points in embedded circles from a given sweepout of the sphere by closed curves.
result Lower bounds for the Birkhoff min-max invariant of a Riemannian sphere in terms of the min-max width of its embedded circles.

Consider a convex polygon P in the plane, and denote by U a homothetical copy of the vector sum of P and (-P). Then the polygon U, as unit ball, induces a norm such that, with respect to this norm, P has constant Minkowskian width. We define notions like Minkowskian curvature, evolutes and involutes for polygons of con…

2014-06-12abs ↗pdf ↗

Improved neural network depth-width trade-offs via dynamical systems.

problem Expressivity of neural networks in terms of depth and width.
method Connection with dynamical systems, focusing on periodic points and Lipschitz constants.
result Sharper width lower bounds for neural networks, yielding exponential depth-width separations.

There are many "minimax" complexity functions in mathematics: width of a tree or a link, Heegaard genus of a 3-manifold, the Cheeger constant of a Riemannian manifold. We define such a function w, "width", on countable (or finite) groups and show w(Z^k) = k-1.

2010-11-10abs ↗pdf ↗

Study finds geodesic networks for surfaces with convex boundary.

problem Finding geodesic networks for surfaces with convex boundary.
method Investigates free boundary geodesic networks in surfaces with non-negative sectional curvature and convex boundary.
result Existence of a geodesic network realizing the first width of a surface with non-negative sectional curvature and strictly convex boundary.

The study reveals a transition in neural network performance from infinite-width to variance-limited behavior as dataset size increases.

problem Understanding the transition from infinite-width to variance-limited behavior in neural networks.
method Empirical study of the transition from infinite-width to variance-limited behavior as a function of sample size and network width.
result The critical sample size \( P^* \) is approximately \( \sqrt{N} \) for polynomial regression with ReLU networks.

New optimizers control network width scaling, improving stability and transfer across different model sizes.

problem Designing stable optimizers for networks of varying widths.
method Interpreting optimizers as steepest descent under mean-normalized operator norms, enabling layerwise composability and width-independent bounds.
result New optimizers like row normalization and column normalization provide stable learning-rate transfer across different model widths.

Lower bound for Steklov eigenvalues on negatively curved manifolds.

problem Finding a geometric lower bound for the first nonzero Steklov eigenvalue.
method Combining a uniform lower bound for the first eigenvalue of the Steklov-Dirichlet problem and a tubular neighborhood theorem for totally geodesic hypersurfaces.
result A geometric lower bound for the first nonzero Steklov eigenvalue in terms of total and boundary volumes.

This paper optimizes ReLU networks for approximating Hölder continuous functions.

problem Optimizing the approximation rate of ReLU networks in terms of width and depth.
method Constructive proof of ReLU networks' approximation power with specific width and depth constraints.
result Optimal approximation rate of ReLU networks with width and depth constraints.

New framework connects two neural network theories, improving finite-width approximations.

problem Theoretical guarantees for neural network training in general cases.
method Developed a general framework linking mean-field and constant kernel theories.
result Discrete-time MF limit provides better approximation for finite-width nets.

We provide an upper bound for the Gromov width of compact homogeneous Hodge manifolds (M,ω)(M, ω) with b2(M)=1b_2(M)=1. As an application we obtain an upper bound on the Seshadri constant ε(L)ε(L) where LL is the ample line bundle on MM such that c1(L)=[ωπ]c_1(L)=[\fracωπ].

2013-11-29abs ↗pdf ↗

This paper studies bounds for the Lipschitz constant of random neural networks.

problem Quantifying the worst-case robustness of neural networks against adversarial perturbations.
method Analyzes upper and lower bounds for the Lipschitz constant of random ReLU neural networks under specific initialization conditions.
result For deep networks, the upper bound is larger than the lower bound by a logarithmic factor in width.

We investigate several integer invariants of curves in 3-space. We demonstrate relationships of these invariants to crossing number and to total curvature.

2006-04-11abs ↗pdf ↗

Study compares hyperbolic and extremal lengths for shortest curves.

problem Comparing hyperbolic and extremal lengths for shortest curves.
method Lower bounds for widths of collars and upper bounds for renormalized volume of Schottky manifolds.
result Upper bounds of renormalized volume in terms of hyperbolic length of compressible curves.

The width of a closed convex subset of Euclidean space is the distance between two parallel supporting planes. The Blaschke-Lebesgue problem consists of minimizing the volume in the class of convex sets of fixed constant width and is still open in dimension n > 2. In this paper we describe a necessary condition that th…

2009-06-17abs ↗pdf ↗

Wider neural networks perform better than deeper ones with the same number of parameters.

problem Understanding the role of network width versus the number of parameters in neural network performance.
method Comparing models with different ways of increasing width while keeping the number of parameters constant, analyzing their performance and using Gaussian Process kernels for analysis.
result Network width is the determining factor for good performance, while the number of weights is secondary as long as trainability is ensured.