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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.

168,657 papers · 148 categories

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149299448597 · Jun 202019922001200920172026
48 results for section existence

The study bounds dimensions and proves existence of holomorphic sections on Kähler Ricci shrinkers.

problem Estimating dimensions and existence of holomorphic sections with polynomial growth on Kähler Ricci shrinkers.
method Proved upper bounds for dimensions and existence of sections using polynomial growth.
result Upper bounds for dimensions and existence of holomorphic sections with polynomial growth on Kähler Ricci shrinkers.

The paper addresses how to add points to existing configurations on surfaces without disrupting continuity.

problem Adding points to existing configurations on orientable surfaces without disrupting continuity.
method Algebraic approach for g1g \geq 1 and m2m \geq 2, geometric approach for g1g \geq 1 and m=1m = 1.
result A necessary condition for the existence of a section is that nn must be a multiple of m+(2g2)m+(2g-2) for g1g \geq 1 and m2m \geq 2.

The paper explores conditions for sections in Lefschetz fibrations and bundles over 2-complexes.

problem Conditions for sections in Lefschetz fibrations and bundles over 2-complexes.
method Algebraic criteria and topological conditions.
result Complete algebraic criterion for sections in Lefschetz fibrations over the disk.

The paper proves the existence of surfaces of section for geodesic flows on closed surfaces.

problem Existence of surfaces of section for geodesic flows on closed surfaces.
method Study of configurations of simple closed geodesics and use of the curve shortening flow.
result Construction of surfaces of section that intersect or have hyperbolic components in their boundary.

The nearly Kähler structures on the 6-sphere, as a twistor bundle sections are researched. We show that for any point of twistor bundle there exists an 1-parametric family of sections, passing through the point, which give nearly Kähler structures on the round sphere. Some properties of those sections are found.

2015-10-16abs ↗pdf ↗

New curvature obstruction for Killing vector fields on Lorentzian manifolds.

problem Existence of timelike or causal Killing vector fields on Lorentzian manifolds.
method New curvature obstruction in terms of timelike or null sectional curvature.
result Extension of Gauss-Bonnet-Chern obstruction to non-zero timelike sectional curvature.

The study proves the non-existence of certain Kähler metrics with specific curvature properties.

problem Non-existence of complete Kähler metrics with negatively pinched holomorphic sectional curvature.
method Construction of a Kähler metric with negatively pinched holomorphic sectional curvature and application of equivalence of invariant metrics.
result The dichotomy of completeness and non-existence of Kähler metrics with negatively pinched holomorphic sectional curvature.

We establish new obstruction results to the existence of Riemannian metrics on tori satisfying mixed bounds on both their sectional and Ricci curvatures. More precisely, from Lohkamp's theorem, every torus of dimension at least three admits Riemannian metrics with negative Ricci curvature. We show that the sectional cu…

2017-07-25abs ↗pdf ↗

Proves section conjecture for curves and surface bundles over various fields.

problem Proving Grothendieck's section conjecture for curves and surface bundles.
method Formulated and proved the section conjecture for stable graphs, used Galois cohomology classes to obstruct sections.
result Proved section conjecture for curves and surface bundles over p-adic and number fields.

The Nielsen Realization problem asks when the group homomorphism from Diff(M) to pi_0 Diff(M) admits a section. For M a closed surface, Kerckhoff proved that a section exists over any finite subgroup, but Morita proved that if the genus is large enough then no section exists over the entire mapping class group. We prov…

2007-05-31abs ↗pdf ↗

The abstract proves that certain Reeb vector fields on 3-manifolds have Birkhoff sections.

problem Existence of Birkhoff sections for Reeb vector fields on 3-manifolds.
method Showed existence of Birkhoff sections for Reeb vector fields satisfying Kupka-Smale condition.
result Reeb vector fields on closed 3-manifolds with Kupka-Smale condition admit Birkhoff sections.

We apply the existence and special properties of Gauduchon metrics to give several applications. The first one is concerned with the implications of algebro-geometric nature under the existence of a Hermitian metric with nonnegative holomorphic sectional curvature. The second one is to show the non-existence of holomor…

2019-12-31abs ↗pdf ↗

The paper defines cross-section continuity for angular momentum definitions and finds the CWY definition valid.

problem Defining angular momentum at null infinity and ensuring its continuity across different cross-sections.
method Introducing cross-section continuity as a criterion and proving it for specific angular momentum definitions.
result The Chen-Wang-Yau definition of angular momentum satisfies cross-section continuity, while the Compere-Nichols modification does not.

This is a survey of motivations, constructions and applications of higher prequantum geometry. In section 1 we highlight the open problem of prequantizing local field theory in a local and gauge invariant way, and we survey how a solution to this problem exists in higher differential geometry. In section 2 we survey ex…

2016-01-22abs ↗pdf ↗

We show that there exists a non-trivial simplified broken Lefschetz fibration which has infinitely many homotopy classes of sections. We also construct a non-trivial simplified broken Lefschetz fibration which has a section with non-negative square. It is known that no Lefschetz fibration satisfies either of the above …

2011-04-06abs ↗pdf ↗

Motivated by a question of Hirzebruch on the possible topological types of cusp cross-sections of Hilbert modular varieties, we give a necessary and sufficient condition for a manifold M to be diffeomorphic to a cusp cross-section of a Hilbert modular variety. Specialized to Hilbert modular surfaces, this proves that e…

2007-06-25abs ↗pdf ↗

This paper studies torsion obstructions to complex sections on manifolds.

problem Torsion obstructions to finding complex sections on almost complex manifolds.
method Calculations using the Adams-Novikov spectral sequence for Thom spectra.
result Torsion obstructions for finding rr complex sections of order pp vanish for r<p2pr < p^2 - p.

In an earlier work, we investigated some consequences of the existence of a Kähler metric of negative holomorphic sectional curvature on a projective manifold. In the present work, we extend our results to the case of semi-negative (i.e., non-positive) holomorphic sectional curvature. In doing so, we define a new invar…

2014-03-17abs ↗pdf ↗

The sectional curvature of the volume preserving diffeomorphism group of a Riemannian manifold MM can give information about the stability of inviscid, incompressible fluid flows on MM. We demonstrate that the submanifold of the volumorphism group of the solid flat torus generated by axisymmetric fluid flows with swi…

2014-09-08abs ↗pdf ↗

Upper bound found for dimensions of subspaces where holomorphic sectional curvature vanishes.

problem Finding upper bounds for dimensions of subspaces where holomorphic sectional curvature vanishes.
method Connection with D'Angelo's work on complex subvarieties of real algebraic varieties and decomposition of polynomials into differences of squares.
result An upper bound for the dimensions of these subspaces is found.

The paper develops quantitative estimates for holomorphic sections over bounded domains.

problem Establishing precise inequalities for holomorphic sections over bounded domains.
method Develops Sobolev-type inequalities and applies them to holomorphic sections of Hermitian vector bundles.
result Quantitative Carleman-type estimates for holomorphic sections are derived, improving on previous non-quantitative results.

The study characterizes spacetimes with quasi-constant sectional curvature and explores their properties in F(R)\mathcal{F}(\mathcal{R})-gravity.

problem Characterizing spacetimes with quasi-constant sectional curvature.
method Investigation through examples, proofs, and analysis of energy conditions.
result A spacetime of quasi-constant sectional curvature can represent a Robertson Walker spacetime or a static spacetime.

We prove that S^2 x S^2 satisfies an intermediate condition between having metrics with positive Ricci and positive sectional curvature. Namely, there exist metrics for which the average of the sectional curvatures of any two planes tangent at the same point, but separated by a minimum distance in the 2-Grassmannian, i…

2012-09-28abs ↗pdf ↗

Ricci flow can change metrics with positive curvature to those without.

problem Preserving positive sectional curvature under Ricci flow in specific dimensions.
method Examined SU3\mathsf{SU}_{3}- and SU5\mathsf{SU}_{5}-invariant metrics on Aloff-Wallach spaces and Berger space.
result Found metrics with positive sectional curvature that evolve to non-positively curved metrics under Ricci flow.

The paper introduces a new concept of frame vorticity and uses it to find optimal sections in specific geometric settings.

problem Finding optimal sections in geometric settings using frame vorticity.
method Defining frame vorticity, relating it to split pseudo-Riemannian metrics, and using split special Lagrangian calibrations.
result Explicit homologically volume maximizing sections and optimal sections for specific manifolds.

Curvature tensors can always be matched to a metric tensor under certain conditions.

problem Sectionally positive curvature tensors and their relationship to metric tensors.
method Existence and uniqueness of a metric tensor gabg_{ab} such that Rabcdgbd=gacλR_{abcd} g^{bd} = g_{ac} λ.
result A metric tensor gabg_{ab} can be found for sectionally positive curvature tensors, and it is unique up to a constant factor.

We survey some recent developments in the quest for global surfaces of section for Reeb flows in dimension three using methods from Symplectic Topology. We focus on applications to geometry, including existence of closed geodesics and sharp systolic inequalities. Applications to topology and celestial mechanics are als…

2017-12-05abs ↗pdf ↗

We study the existence problem and the enumeration problem for sections of Serre fibrations over compact orientable surfaces. When the fundamental group of the fiber is finite, a complete solution is given in terms of 2-dimensional cohomology classes associated with certain irreducible representations of this group. Th…

2009-04-17abs ↗pdf ↗

It was proved by H. Whitney in 1933 that a Serre fibration of compact metric spaces admits a global section provided every fiber is homeomorphic to the unit interval [0,1]. An extension of the Whitney's theorem to the case when all fibers are homeomorphic to some fixed compact two-dimensional manifold was proved by the…

2009-02-19abs ↗pdf ↗

We consider the normalized Ricci flow evolving from an initial metric which is conformally compactifiable and asymptotically hyperbolic. We show that there is a unique evolving metric which remains in this class, and that the flow exists up to the time where the norm of the Riemann tensor diverges. Restricting to initi…

2015-06-22abs ↗pdf ↗