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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.

169,291 papers · 148 categories

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8.3%16.7%25.0%33.3% · Jul 199219922001200920182026
48 results for collar neighborhoods

Derives generalizations of the long neck principle and spectral width inequality.

problem Understanding the spectral width of geodesic collar neighborhoods.
method Spinorial Callias operator approach and relative Gromov-Lawson pair.
result Generalizations of the long neck principle and spectral width inequality.

We discuss two generalizations of the collar lemma. The first is the stable neighborhood theorem which says that a (not necessarily simple) closed geodesic in a hyperbolic surface has a \lq\lq stable neighborhood\rq\rq whose width only depends on the length of the geodesic. As an application, we show that there is a lo…

1992-07-01abs ↗pdf ↗

The paper extends the collar theorem to non-compact surfaces using new comparison theorems.

problem Proving the collar theorem for non-compact surfaces.
method Developed new Toponogov-type triangle comparison theorems.
result Eliminated the compactness hypothesis for the collar theorem.

New examples show manifolds with noncompact boundaries that can't be pseudo-collarable.

problem Identifying manifolds with noncompact boundaries that cannot be pseudo-collarable.
method Provided examples of Z\mathcal{Z}-compactifiable manifolds with noncompact boundaries that fail to be pseudo-collarable.
result Found manifolds with noncompact boundaries that cannot be pseudo-collarable.

Positive representations on surfaces have positive cross-ratios and satisfy a collar lemma.

problem Characterizing representations of surface groups with positive properties.
method Proving a collar lemma and showing positivity of cross-ratios for ΘΘ-positive representations.
result Closed subsets of representation varieties are characterized by ΘΘ-positive representations.

The notion of an open collar is generalized to that of a pseudo-collar. Important properties and examples are discussed. The main result gives conditions which guarantee the existence of a pseudo-collar structure on the end of an open n-manifold (n > 6). This paper may be viewed as a generalization of Siebenmann's famo…

2001-01-04abs ↗pdf ↗

In this note we define the notion of collarable slices of Lagrangian submanifolds. Those are slices of Lagrangian submanifolds which can be isotoped through Lagrangian submanifolds to a cylinder over a Legendrian embedding near a contact hypersurface. Such a notion arises naturally when studying intersections of Lagran…

2011-08-15abs ↗pdf ↗

Characterizes pseudo-collarable manifolds with noncompact boundaries.

problem Characterizing manifolds with noncompact boundaries.
method Extends earlier work by Guilbault and Tinsley to include noncompact boundaries, extending Siebenmann's work.
result Complete characterization of pseudo-collarable nn-manifolds for n6n\geq 6.

The paper solves conditions for extending circle-valued Morse functions.

problem Conditions for extending circle-valued Morse functions on closed orientable surfaces.
method Provided necessary and sufficient conditions for the existence of a non-singular extension.
result Necessary and sufficient conditions for the existence of a non-singular extension of a circle-valued Morse function.

We consider an arbitrary linear elliptic first--order differential operator A with smooth coefficients acting between sections of complex vector bundles E,F over a compact smooth manifold M with smooth boundary N. We describe the analytic and topological properties of A in a collar neighborhood U of N and analyze vario…

2008-03-28abs ↗pdf ↗

The paper connects curvature data to polynomial coefficients in gluing formulas.

problem Understanding polynomial coefficients in gluing formulas for zeta-determinants.
method Expressing coefficients of a polynomial in terms of scalar and principal curvatures of a 2D hypersurface.
result Coefficients of the polynomial are expressed in terms of curvature data.

Study parabolicity of Riemann surfaces via Fenchel-Nielsen parameters.

problem Determine conditions for a Riemann surface to be of parabolic type.
method Use Fenchel-Nielsen parameters and non-standard half-collars to study parabolicity.
result Obtain sufficient conditions for parabolicity in terms of Fenchel-Nielsen parameters.

This paper concerns a formula which relates the Lefschetz number L(f) for a map f:M --> M' to the fixed point index I(f) summed with the fixed point index of a derived map on part of the boundary of M. Here M is a compact manifold and M' is M with a collar attached.

2005-05-11abs ↗pdf ↗

In this paper, we recall Quillen's plus construction for high-dimensional smooth manifolds and the solution to the group extension problem. We then develop a geometric procedure due for producing a "reverse" to the plus construction, a one-sided s-cobordism called a semi-s-cobordism, when the total group of the group e…

2015-02-15abs ↗pdf ↗

We continue our study of ends non-compact manifolds. The over-arching aim is to provide an appropriate generalization of Siebenmann's famous collaring theorem that applies to manifolds having non-stable fundamental group systems at infinity. In this paper a primary goal is finally achieved; namely, a complete character…

2005-05-24abs ↗pdf ↗

For compact Riemann surfaces, the collar theorem and Bers' partition theorem are major tools for working with simple closed geodesics. The main goal of this paper is to prove similar theorems for hyperbolic cone-surfaces. Hyperbolic two-dimensional orbifolds are a particular case of such surfaces. We consider all cone …

2004-05-07abs ↗pdf ↗

The paper establishes distance estimates for manifolds with lower scalar curvature bounds.

problem Distance estimates on manifolds with lower scalar curvature bounds.
method Introduced a definition of relative index via a deformed Dirac operator trick and proved index coincidence with Callias operators.
result Proved short neck inequality and quantitative shielding result with positive scalar curvature.

Stability of Morse index for harmonic maps on degenerating surfaces analyzed.

problem Analyzing stability of Morse index for harmonic maps on degenerating Riemann surfaces.
method Analysis of second variation of energy, identification of conditions for upper semicontinuity, explicit contribution of geodesics.
result Sharper control of spectrum of Jacobi operator, explicit contribution of geodesic segments to Morse index.

We use Furuta's result, usually referred to as ``10/8-conjecture'', to show that for any compact 3-manifold MM the open manifold $M\times\r$ has infinitely many different smooth structures. Another consequence of Furuta's result is existence of infinitely many smooth structures on open topological 4-manifolds with a t…

1996-04-26abs ↗pdf ↗

We consider cohomogeneity one homogeneous disk bundles and adress the question when these admit a nonnegatively curved invariant metric with normal collar, i.e., such that near the boundary the metric is the product of an interval and a normal homogeneous space. If such a bundle is not (the quotient of) a trivial bundl…

2008-06-24abs ↗pdf ↗

New examples of non-smoothable homeomorphisms of 4-manifolds with boundary found.

problem Finding non-smoothable homeomorphisms of 4-manifolds with boundary.
method Constructing specific examples of homeomorphisms that fix the boundary and act trivially on homology.
result First examples of non-smoothable self-homeomorphisms of smooth 4-manifolds with boundary.

Positive representations of surface groups in PO(p,q) form connected components of character varieties.

problem Characterizing representations of surface groups in special orthogonal groups PO(p,q).
method Using Anosov representations and root versus weight collar lemmas.
result Connected components of character varieties are formed by ΘΘ-positive Anosov representations.

The paper sets geometric lower bounds for low Steklov eigenvalues on manifolds.

problem Finding geometric lower bounds for low Steklov eigenvalues on manifolds.
method Using trace inequalities relating Steklov eigenvalues to Neumann eigenvalues of subdomains containing boundary collars.
result Geometric lower bounds for low Steklov eigenvalues, complementing earlier results.

Sharp eigenvalue estimates on degenerating hyperbolic surfaces.

problem Estimating the first non-zero eigenvalue of Laplacian on hyperbolic surfaces as a collar degenerates.
method Using the relationship between the eigenvalue and Fenchel-Nielsen length coordinate, proving estimates with optimal error rates.
result Improved estimates and new information on leading order terms of eigenvalue expansion.

Arithmetic spaces simplified to simplicial complexes.

problem Understanding the complexity of arithmetic locally symmetric spaces.
method Homotopy equivalence to a simplicial complex with linearly bounded simplices, using a strengthened Margulis collar lemma.
result Arithmetic locally symmetric spaces are homotopy equivalent to simplicial complexes with linearly bounded simplices.

Proves a theorem for normal distributions on manifolds with boundary.

problem Normal distributions on manifolds with boundary require a new approach to integration.
method Introduces neat integral manifolds with boundary and conditions for integrability.
result Conditions for integrability expressed in terms of adapted collars and integrability on interior and boundary.

Study applies Penrose and mass theorems to 33-manifolds with nonnegative scalar curvature and CMC boundary.

problem Derive inequalities on compact 33-manifolds with nonnegative scalar curvature and CMC boundary.
method Apply Riemannian Penrose inequality and positive mass theorem; construct a collar extension.
result Prove inequalities on the boundary of compact 33-manifolds with nonnegative scalar curvature and CMC boundary.

Let F\mathbb F be a real closed field. We define the notion of a maximal framing for a representation of the fundamental group of a surface with values in Sp(2n,F){\rm Sp}(2n,\mathbb F). We show that ultralimits of maximal representations in Sp(2n,R){\rm Sp}(2n,\mathbb R) admit such a framing, and that all maximal framed represen…

2015-09-03abs ↗pdf ↗

In this paper we continue an earlier study of ends non-compact manifolds. The over-arching goal is to investigate and obtain generalizations of Siebenmann's famous collaring theorem that may be applied to manifolds having non-stable fundamental group systems at infinity. In this paper we show that, for manifolds with c…

2003-04-02abs ↗pdf ↗

The study explores deep and shallow slice knots in 4-manifolds, linking them to conjectures and proving existence and nonexistence results.

problem Understanding slice knots in 4-manifolds and their properties.
method Using Wall self-intersection invariant and Rohlin's result, the study examines various 4-manifolds and their boundaries to find deep slice knots and prove nonexistence results.
result Every 4-manifold with one 0-handle and any number of 2-handles has a deep slice knot in its boundary.

Researchers approximate spectral targets on manifolds with constant negative curvature.

problem Prescribing an arbitrary finite portion of the Laplace-Beltrami spectrum on manifolds of constant negative curvature.
method Constructing macroscopically heterogeneous hyperbolic covering manifolds in d3d\ge3 and using discrete spectral limit theorems in d=2d=2.
result Any finite strictly increasing target list can be approximated to arbitrary precision by a closed manifold of constant negative curvature.

We show that if the totally geodesic boundary of a compact hyperbolic 3-manifold M has a large collar of depth d, then the diameter of the skinning map of M is no more than A exp(-d) for some A depending only on the genus and injectivity radius of the boundary of M.

2013-05-10abs ↗pdf ↗