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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.

168,695 papers · 148 categories

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72144216288 · May 202619922001200920172026
48 results for intrinsically harmonic forms

The n-dimensional torus is uniquely characterized by specific harmonic forms.

problem Characterizing the n-dimensional torus via harmonic forms.
method Analyzing closed 1-forms on the torus to determine unique properties.
result The n-dimensional torus is the unique manifold supporting a linearly independent set of (n-1) closed 1-forms whose product determines a non-zero cohomological class.

We discuss the construction of Sp(2)Sp(1)-structures whose fundamental form is closed. In particular, we find 10 new examples of 8-dimensional nilmanifolds that admit an invariant closed 4-form with stabiliser Sp(2)Sp(1). Our constructions entail the notion of SO(4)-structures on 7-manifolds. We present a thorough inve…

2013-08-19abs ↗pdf ↗

The paper studies harmonic graphs in the Heisenberg group and their properties.

problem No analogous theorem exists for HH-minimal surfaces in the Heisenberg group.
method Introduced intrinsic Dirichlet energy and studied its critical points (contact harmonic graphs).
result Calibration condition and construction of energy-minimizing graphs with various singularities.

Bayesian framework for sphere regression using Gaussian fields.

problem Nonparametric regression on the sphere with Gaussian priors.
method Isotropic Gaussian field priors, harmonic structure, exact posterior distributions, optimal spectral truncation, posterior contraction rates.
result Sharp posterior contraction rates for Gaussian priors with polynomially decaying angular power spectra.

Let MM be a closed oriented manifold of dimension nn and ωω a closed 1-form on it. We discuss the question whether there exists a Riemannian metric for which ωω is co-closed. For closed 1-forms with nondegenerate zeros the question was answered completely by Calabi in 1969. The goal of this paper is to give an answ…

2007-06-15abs ↗pdf ↗

Proves harmonic coordinates for weak immersions in even dimensions.

problem Existence of harmonic coordinates for weak immersions in Sobolev spaces.
method Analyzes weak immersions in critical Sobolev spaces and uses smallness conditions on the second fundamental form.
result Global harmonic coordinates exist for weak immersions in even dimensions under certain conditions.

We go further on the study of harmonicity for almost contact metric structures already initiated by Vergara-Diaz and Wood. By using the intrinsic torsion, we characterise harmonic almost contact metric structures in several equivalent ways and show conditions relating harmonicity and classes of almost contact metric st…

2008-10-08abs ↗pdf ↗

Study topological properties of foliations induced by closed 1-forms on orbifolds.

problem Characterize the topology of foliation leaves induced by closed 1-forms on orbifolds.
method Establish criteria for the compactness of foliation leaves and extend a topological result to orbifolds.
result Criteria for the compactness and coexistence of foliation leaves are established.

Let (M,I, ω, Ω) be a nearly Kaehler 6-manifold, that is, an SU(3)-manifold with the (3,0)-form Ωand the Hermitian form ωwhich satisfies dω=3λΩ,dΩ=2λω2dω=3λ\ReΩ, d\ImΩ=-2λω^2, for a non-zero real constant λ. We develop an analogue of Kaehler relations on M, proving several useful identities for various intrinsic Laplacians on M. Wh…

2005-10-28abs ↗pdf ↗

The paper investigates Liouville type theorems for various harmonic forms on Riemannian manifolds.

problem Investigating Liouville type properties of harmonic forms on Riemannian manifolds.
method Normalized integral Ricci curvature and BiRic curvature.
result Established Liouville theorems for pp-harmonic function, pp-harmonic 1 form, and harmonic qq form (with q2q \geq 2).

The study of harmonicity for almost contact metric structures was initiated by Vergara-Díaz and Wood and continued by González-Dávila and the present author. By using the intrinsic torsion and some restriction on the type of almost contact metric structure, González-Dávila and the present author have characterised harm…

2019-07-04abs ↗pdf ↗

New metrics produce discrete zero sets for nondegenerate harmonic forms.

problem Creating metrics to produce discrete zero sets for nondegenerate harmonic forms.
method Metric perturbation to produce new nondegenerate harmonic forms with discrete zero sets.
result Existence of metrics producing discrete zero sets for nondegenerate harmonic forms.

The study resolves a conjecture about harmonic forms on compact manifolds.

problem Finding non-degenerate Z2\mathbb{Z}_{2}-harmonic 1-forms on compact manifolds.
method Develops a gluing theorem for non-degenerate Z2\mathbb{Z}_{2}-harmonic 1-forms on compact manifolds.
result Proves the existence of non-degenerate Z2\mathbb{Z}_{2}-harmonic 1-forms on compact manifolds with positive first Betti number.

The study examines harmonic forms on almost Hermitian manifolds and complex surfaces.

problem Analyzing harmonic forms on almost Hermitian manifolds and complex surfaces.
method Using techniques from Bott-Chern and Aeppli numbers, the study generalizes harmonic forms from complex and symplectic manifolds to almost Hermitian manifolds.
result Bott-Chern and Aeppli numbers of compact complex surfaces depend only on the topology of the underlying manifold.

Study primitive decompositions for harmonic forms on almost Kähler manifolds.

problem Decomposing harmonic forms on almost Kähler manifolds.
method Proved primitive decompositions for Bott-Chern and Aeppli harmonic forms in specific bidegrees.
result Optimal bidegrees for primitive decompositions of harmonic forms.

The study finds nondegenerate harmonic 1-forms using symmetry conditions.

problem Existence of nondegenerate harmonic 1-forms over Riemannian manifolds.
method Utilizing Z3\mathbb{Z}_3 symmetry to establish topological conditions.
result Found nondegenerate Z2\mathbb{Z}_2 harmonic 1-forms over branched coverings of links.

The study shows that the second fundamental form is intrinsic under certain conditions in space forms.

problem Understanding the intrinsic nature of the second fundamental form in space forms.
method Proving the intrinsic nature of the normalized second fundamental form AA under specific conditions.
result The normalized second fundamental form AA is intrinsic if σ2k+1(A)eq0σ_{2k+1}(A) eq 0 for some k1k\ge 1.

Symmetry operators of twistor spinors and harmonic spinors can be constructed from conformal Killing-Yano forms. Transformation operators relating twistors to harmonic spinors are found in terms of potential forms. These constructions are generalized to gauged twistor spinors and gauged harmonic spinors. The operators …

2017-04-16abs ↗pdf ↗

In general, the product of harmonic forms is not harmonic. We study the top exterior power of harmonic two-forms on compact Kaehler manifolds. Often, it is not harmonic. This phenomenon is related to the geometry of the manifold and to the existence of rational curves in particular. K3 surfaces and hyperkaehler manifol…

2000-03-29abs ↗pdf ↗

The paper constructs harmonic 1-forms on 3-manifolds with cylindrical necks.

problem Stabilizing Z/2-harmonic 1-forms on closed 3-manifolds.
method Explicit construction of harmonic 1-forms by modifying metrics near links.
result Construction of harmonic 1-forms degenerating to manifolds with cylindrical ends.

Study L2L^{2}-harmonic forms on almost Kähler manifolds, extending vanishing theorems.

problem Analyzing L2L^{2}-harmonic forms on complete almost Kähler manifolds.
method Decomposing L2L^{2}-harmonic forms into Lefschetz powers of primitive forms, extending vanishing theorems.
result Spaces of harmonic (p,q)(p,q)-forms on XX vanish unless p+q=np+q=n.

Analyzes L2L^{2}-harmonic forms on curved manifolds, proving integrability conditions.

problem Analyzing integrability of L2L^{2}-harmonic forms on curved manifolds.
method Established LL^{\infty}-estimate via Moser iteration, proved vanishing of integrable forms.
result Proves that L2L^{2}-harmonic forms on non-positively curved manifolds are integrable if and only if they vanish.

New examples of Z/2 harmonic 1-forms and their branching sets are explored.

problem Exploring the properties and examples of Z/2 harmonic 1-forms and their branching sets.
method Elementary constructions and families of Z2\Z_2 harmonic 1-forms.
result The branching set ΣΣ of a Z2\Z_2 harmonic 1-form can exhibit various features including non-trivial links, multiple covers, and immersed structures.

Quantifies uniqueness of conformal-harmonic maps on 4-manifolds.

problem Quantifying uniqueness of conformal-harmonic maps on 4-manifolds.
method Proves a quantitative uniqueness result using convexity and second order Hardy inequality.
result Proves a version of second order Hardy inequality on manifolds.

The paper introduces new cohomologies and studies harmonic forms on almost complex manifolds.

problem Understanding cohomologies and harmonic forms on almost complex manifolds.
method Introducing new cohomologies (Bott-Chern and Aeppli) and studying associated harmonic forms.
result Bott-Chern cohomology of 1-forms is finite-dimensional on compact manifolds and provides an invariant.

We prove that manifolds admitting a Riemannian metric for which products of harmonic forms are harmonic satisfy strong topological restrictions, some of which are akin to properties of flat manifolds. Others are more subtle, and are related to symplectic geometry and Seiberg-Witten theory. We also prove that a manifold…

2000-04-02abs ↗pdf ↗