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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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48 results for ball complexes

Study shows no smooth embeddings of rational homology balls into complex projective plane.

problem Embedding rational homology balls into complex projective plane.
method Elementary arguments to prove non-existence of almost complex embeddings.
result No smooth embeddings of rational homology balls into complex projective plane.

This paper classifies ball quotients of the complex projective plane.

problem Understanding the structure of the complex projective plane as a ball quotient.
method Analyzing the branch locus as a line arrangement and smooth normal-crossing curves.
result The orbifold structure of (P2,D)(\mathbb{P}^2,D) is isomorphic to either the Deligne-Mostow example or a certain degree 9 cover.

Smooth but not symplectic embeddings of rational balls in complex projective plane found.

problem Finding smooth embeddings of rational balls in complex projective plane that are not symplectic.
method Infinite family of rational homology balls, lattice embedding obstruction from Donaldson's diagonalisation theorem.
result No two examples may be embedded disjointly.

In this paper we get an explicit lower bound for the radius of a Bergman ball contained in the Dirichlet fundamental polyhedron of a torsion-free discrete group GPU(n,1)G\subset PU(n,1) acting on complex hyperbolic space. Consequently the volume of all complex hyperbolic n-manifolds is bounded below by the volume of this bal…

2012-03-16abs ↗pdf ↗

The paper introduces new boundary operators and proves higher order CR Sobolev trace inequalities for Siegel domain and complex ball.

problem Establishing higher order CR Sobolev trace inequalities for Siegel domain and complex ball.
method Introducing conformally covariant boundary operators, proving extension theorems, and establishing trace inequalities.
result Generalized CR Sobolev trace inequalities for all γ ∈ (0, n+1) \mathbb{N}.

Regularizes complex functions on manifolds using coordinate balls.

problem Regularizing quasi-plurisubharmonic functions on compact Kaehler manifolds.
method Regularize on local coordinate balls, then glue, focusing on vanishing higher order terms at centers.
result Higher order terms vanish at centers of coordinate balls, forming a delta-net.

The Farey tree helps embed rational balls and lens spaces into complex projective space.

problem Embedding rational homology balls and lens spaces into complex projective space.
method Recursive Kirby calculus argument using the Farey tree.
result Explicit constructions of embeddings of triples of rational homology balls into homotopy CP2\mathbb{CP}^2.

Call a smooth knot (or smooth link) in the unit sphere in C2\mathbb{C}^2 analytic (respectively, smoothly analytic) if it bounds a complex curve (respectively, a smooth complex curve) in the complex ball. Let KK be a smoothly analytic knot. For a small tubular neighbourhood of KK we give a sharp lower bound for the 4…

2015-04-24abs ↗pdf ↗

Symplectic embeddings of balls into specific manifolds are studied, with restrictions and obstructions identified.

problem Understanding symplectic embeddings of balls into complex projective spaces, tori, and K3 surfaces.
method Analyzing embeddings with respect to complex structures compatible with the symplectic form and identifying obstructions.
result Symplectic volume is the primary obstruction for the existence of embeddings of balls into certain manifolds.

Results of R. Stanley and M. Masuda completely characterize the h-vectors of simplicial posets whose order complexes are spheres. In this paper we examine the corresponding question in the case where the order complex is a ball. Using the face rings of these posets, we develop a series of new conditions on their h-vect…

2010-09-10abs ↗pdf ↗

Mapper and Ball Mapper tools for complex data analysis.

problem Exploring and visualizing high-dimensional data and scalar functions.
method Combining Mapper and Ball Mapper, adding new features for encoding structure and symmetries.
result A new hybrid algorithm, Mapper on Ball Mapper, for comparing high-dimensional data descriptors.

Researchers create a smooth family of metrics on a ball, including hyperbolic and complex hyperbolic metrics.

problem Constructing Poincaré-Einstein metrics on the ball.
method Gibbons-Hawking-type ansatz of Page and Pope.
result The family of metrics includes the hyperbolic metric and converges to complex hyperbolic at one end.

Study cohomology of ball quotients and their compactifications.

problem Cohomology of symmetric power of cotangent bundles of ball quotients and their compactifications.
method Hodge theory for complete hermitian manifolds, Green's operator, extension of results.
result Established existence of Hodge decomposition and Green's operator for ball quotients and their compactifications.

The paper explores ball quotient compactifications and their properties.

problem Smooth toroidal compactifications of ball quotients cannot contain properly holomorphically embedded 3-punctured spheres.
method Use totally geodesic punctured spheres to prove ampleness of KX+αDK_X + αD for α(14,1)α\in (\frac{1}{4}, 1).
result First examples of bielliptic ball quotient compactifications are produced.

New symplectic caps and embeddings found in complex projective plane.

problem Embeddings of homology balls in complex projective plane.
method Handlebody construction of symplectic caps and embeddings.
result First examples of symplectic handlebody decompositions of a closed symplectic 4-manifold.

New method constructs non-arithmetic hyperbolic orbifolds from complex arithmetic ball quotients.

problem Creating non-arithmetic lattices in projective orthogonal groups.
method Using anti-holomorphic involutions on complex arithmetic ball quotients, gluing fixed loci along geodesic subspaces.
result Explicit calculation of the volume of constructed non-arithmetic orbifolds.

Proves condition for 4-manifolds with sphere boundary to be standard.

problem Determining when acyclic 4-manifolds with sphere boundary are standard.
method Uses Turaev's shadows to provide a sufficient condition for diffeomorphism to the standard 4-ball.
result If a compact, smooth, acyclic 4-manifold with sphere boundary has shadow-complexity at most 2, it is diffeomorphic to the standard 4-ball.

We introduce the non-pure versions of simplicial balls and spheres with minimum number of vertices. These are a special type of non-homogeneous balls and spheres (NH-balls and NH-spheres) satisfying a minimality condition on the number of maximal simplices. The main result is that minimal NH-balls and NH-spheres are pr…

2014-06-25abs ↗pdf ↗

The unit ball is characterized by a Kähler-Einstein potential.

problem Characterizing the unit ball in complex geometry.
method Using a global potential function of the Kähler-Einstein metric.
result A compact Kähler manifold with an ample canonical bundle is the unit ball if it has a specific potential function.

In this paper we prove the existence of rational homology balls smoothly embedded in regular neighborhoods of certain linear chains of smooth 22-spheres by using techniques from minimal model program for 3-dimensional complex algebraic variety.

2015-08-15abs ↗pdf ↗

Researchers study curvature invariants on complex domains, finding rigidity for unit balls.

problem Determine if obstruction flat boundary in C2\mathbb{C}^2 implies biholomorphic equivalence to the unit ball.
method Analyze curvature invariants and their vanishing orders on bounded strictly pseudoconvex domains.
result The unit ball in C2\mathbb{C}^2 is rigid with respect to deformations in the class of strictly pseudoconvex domains with obstruction flat boundary.

The study examines the topology of complements of polytopal skeletons.

problem Characterizing topological properties of polytopal complexes and their skeletons.
method Constructing a long exact sequence relating homologies of skeleton complements and links of faces.
result Characterizations of Cohen-Macaulay and Leray complexes, stacked balls, and neighbourly spheres in terms of skeleton complements.

Three new efficient algorithms project vectors onto weighted l1 ball.

problem Sparse system identification and feature selection.
method Projected gradient descent algorithms with linear or highly competitive quadratic worst case complexities.
result Efficient tools for machine learning methods like compress sensing and feature selection.

In 1967, Chillingworth proved that all convex simplicial 3-balls are collapsible. Using the classical notion of tightness, we generalize this to arbitrary manifolds: We show that all tight simplicial 3-manifolds admit some perfect discrete Morse function. We also strengthen Chillingworth's theorem by proving that all c…

2012-02-15abs ↗pdf ↗

Study on volume growth of metric balls on unbounded hypersurfaces in complex space.

problem Understanding volume growth rates of metric balls on unbounded model hypersurfaces.
method Analyzing the Carnot-Carathéodory metric on unbounded model hypersurfaces in C2\mathbb{C}^2.
result Metric balls of radius δ1δ\gg 1 have volume on the order of δ3δ^3 or δ4δ^4 depending on the hypersurface structure.

Paper proves interior regularity estimates for complex Monge-Ampère solutions.

problem Interior regularity of solutions to complex Monge-Ampère equations.
method Proves interior C1,α\mathcal C^{1,α} and C0,α\mathcal C^{0,α} estimates for solutions with C1,α\mathcal C^{1,α} and C0,α\mathcal C^{0,α} data.
result Generalizes Bedford-Taylor interior C1,1\mathcal C^{1,1} estimate to C1,α\mathcal C^{1,α} and C0,α\mathcal C^{0,α}.