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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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15304459 · Jun 202019922001200920172026
48 results for almost paracomplex

Study connects Lie groups to specific Riemannian manifolds.

problem Understanding Lie groups through Riemannian manifold properties.
method Investigates Lie groups as 3D almost paracontact almost paracomplex Riemannian manifolds.
result Established correspondence between Lie algebra and matrix representation.

The paper explores almost paracomplex structures on 4-manifolds and their properties.

problem Existence and properties of isometric and anti-isometric almost paracomplex structures on pseudo-Riemannian 4-manifolds.
method Analyzes the conditions under which these structures are parallel and their implications for the scalar curvature and Einstein metrics.
result If an isometric or anti-isometric almost paracomplex structure on a conformally flat manifold is parallel, the scalar curvature of the metric must be zero.

Study on a specific type of Riemannian manifolds constructed from 2D space-forms.

problem Characterizing and understanding new types of Riemannian manifolds.
method Constructed as a product of a real line and a 2-dimensional Riemannian space-form, with metrics derived from cone and hyperbolic extensions.
result Characterized and studied in terms of their curvature properties.

Study on hyperspheres in 4-spaces as special Riemannian manifolds.

problem Characterizing hyperspheres in Euclidean and Minkowski 4-spaces as specific Riemannian manifolds.
method Constructing and studying hyperspheres in 4-dimensional spaces (Euclidean and pseudo-Euclidean) as almost paracontact almost paracomplex Riemannian manifolds.
result Characterization and geometric properties of these manifolds.

The paper studies sections of time-like twistor spaces with specific covariant derivatives.

problem Sections of time-like twistor spaces with light-like or zero covariant derivatives.
method Analyzes conformal Gauss maps of time-like minimal surfaces and properties of almost paracomplex structures.
result Sections of time-like twistor spaces have light-like or zero covariant derivatives.

Almost paracontact manifolds of an odd dimension having an almost paracomplex structure on the paracontact distribution are studied. The components of the fundamental (0,3)-tensor, derived by the covariant derivative of the structure endomorphism and the metric on the considered manifolds in each of the basic classes, …

2018-05-28abs ↗pdf ↗

New connections defined for a specific geometric structure.

problem Characterizing manifolds with a paracontact structure.
method Introduced and studied a pair of associated Schouten-van Kampen affine connections.
result Curvature properties of the connections are obtained.

Necessary and sufficient conditions for the existence of a hyper-parahermitian connection with totally skew-symmetric torsion (HPKT-structure) are presented. It is shown that any HPKT-structure is locally generated by a real (potential) function. An invariant first order differential operator is defined on any almost h…

2004-05-31abs ↗pdf ↗

Let G=HKG=H\ltimes K denote a semidirect product Lie group with Lie algebra g=hk\mathfrak g=\mathfrak h \oplus \mathfrak k, where k\mathfrak k is an ideal and h\mathfrak h is a subalgebra of the same dimension as k\mathfrak k. There exist some natural split isomorphisms SS with S2=±IdS^2=\pm \,Id on g\mathfrak g: given an…

2016-04-28abs ↗pdf ↗

We investigate the integrability of natural almost complex structures on the twistor space of an almost para-quaternionic manifold as well as the integrability of natural almost paracomplex structures on the reflector space of an almost para-quaternionic manifold constructed with the help of a para-quaternionic connect…

2005-11-27abs ↗pdf ↗

We study the pseudoriemannian geometry of almost parahermitian manifolds, obtaining a formula for the Ricci tensor of the Levi-Civita connection. The formula uses the intrinsic torsion of an underlying SL(n,R)-structure; we express it in terms of exterior derivatives of some appropriately defined differential forms. As…

2016-05-06abs ↗pdf ↗

Study para-Ricci-like solitons on special Riemannian manifolds, proving geometric properties and providing an example.

problem Characterize para-Ricci-like solitons on para-Sasaki-like Riemannian ΠΠ-manifolds.
method Analyzed different cases of potential vectors and proved geometric properties of constructed objects.
result Obtained results for a parallel symmetric second-order covariant tensor and provided an explicit example.

We analyze the classic problem of existence of Einstein metrics in a given conformal structure for the class of conformal structures inducedf Nurowski's construction by (oriented) (2,3,5) distributions. We characterize in two ways such conformal structures that admit an almost Einstein scale: First, they are precisely …

2016-06-03abs ↗pdf ↗

New Einstein metrics found from para-Sasaki-like Riemannian manifolds.

problem Finding new Einstein metrics in Riemannian geometry.
method Cone construction and hyperbolic extension of paracontact paracomplex Riemannian manifolds.
result New complete Einstein para-Sasaki-like Riemannian manifolds with negative scalar curvature.

Study para-complex structures on specific Lie groups, finding explicit forms and properties.

problem Characterizing para-Kähler structures on six-dimensional nilpotent Lie groups.
method Examined left-invariant para-complex structures on six-dimensional nilpotent Lie groups, obtained explicit expressions and investigated curvature properties.
result Para-complex structures are nilpotent and para-Kähler metrics are Ricci-flat.

On a smooth manifold M, generalized complex (generalized paracomplex) structures provide a notion of interpolation between complex (paracomplex) and symplectic structures on M. Given a complex manifold (M,j), we define six families of distinguished generalized complex or paracomplex structures on M. Each one of them in…

2013-09-27abs ↗pdf ↗

We recall the presentation of the generalized, complex structures by classical tensor fields, while noticing that one has a similar presentation and the same integrability conditions for generalized, paracomplex and subtangent structures. This presentation shows that the generalized, complex, paracomplex and subtangent…

2005-11-01abs ↗pdf ↗

A set of canonical parahermitian connections on an almost paraHermitian manifold is defined. ParaHermitian version of the Apostolov-Gauduchon generalization of the Goldberg-Sachs theorem in General Relativity is given. It is proved that the Nijenhuis tensor of a Nearly paraKähler manifolds is parallel with respect to t…

2003-10-26abs ↗pdf ↗

The paper studies null hypersurfaces in 4-manifolds with a specific metric structure.

problem Characterizing geometric properties of null hypersurfaces in 4-manifolds.
method Analyzes hypersurfaces null with respect to a neutral metric derived from a Riemannian Einstein metric and an almost paracomplex structure.
result Shows that totally geodesic null hypersurfaces imply Ricci-flatness of the ambient Einstein metric and provides necessary conditions for other types of null hypersurfaces.

It is the aim of this work to study product structures on four dimensional solvable Lie algebras. We determine all possible paracomplex structures and consider the case when one of the subalgebras is an ideal. These results are applied to the case of Manin triples and complex product structures. We also analyze the thr…

2004-02-13abs ↗pdf ↗

We show that every paracomplex space form is locally isometric to a modified Riemannian extension and give necessary and sufficient conditions so that a modified Riemannian extension is Einstein. We exhibit Riemannian extension Osserman manifolds of signature (3,3) whose Jacobi operators have non-trivial Jordan normal …

2009-01-12abs ↗pdf ↗

The paper studies nilpotent structures in oriented neutral vector bundles and neutral hyperKähler structures.

problem Nilpotent structures in oriented neutral vector bundles and their relation to neutral hyperKähler structures.
method Defined HH-nilpotent structures for Lie subgroups of SO(2n,2n)SO(2n, 2n) related to neutral hyperKähler structures.
result Existence of complex and paracomplex structures forming neutral hyperKähler structures if and only if there exists an HH-nilpotent structure.

Unified treatment of spacelike and timelike minimal surfaces via Liouville equation.

problem Investigating minimal surfaces in Lorentz-Minkowski space.
method Complex and paracomplex analysis, Möbius-type transformations, pseudo-isometries.
result Unified approach to both spacelike and timelike minimal surfaces.

Study on surfaces in neutral space forms with zero mean curvature.

problem Characterizing surfaces with zero mean curvature in neutral space forms.
method Analyzing curvature and normal connection properties of time-like conformal immersions.
result Conditions for surfaces with zero mean curvature in neutral space forms.

Harmonic almost complex structures on specific Lie groups and solvmanifolds identified.

problem Characterizing harmonic almost complex structures on almost abelian Lie groups and solvmanifolds.
method Adapted Gray-Hervella classification to almost abelian Lie groups, characterized harmonic structures.
result Examples of harmonic almost complex structures in different Gray-Hervella classes on compact almost abelian solvmanifolds.

The paper defines and constructs almost complex blow-ups on 4D almost complex manifolds.

problem Existence and uniqueness of almost complex blow-ups on almost complex manifolds.
method Definition and construction of almost complex blow-ups, proving their existence and uniqueness.
result Existence and uniqueness of almost complex blow-ups on 4D almost complex manifolds.

Study computes invariants on six-dimensional solvmanifolds, providing symplectic structure obstructions.

problem Computing invariants on six-dimensional solvmanifolds.
method Computed almost-complex and almost-Hermitian invariants on families of solvmanifolds.
result Provides obstructions to symplectic structures on compact almost-complex manifolds.

Conditions for Penrose-Ward transformation on specific manifolds.

problem Conditions for Penrose-Ward transformation on almost G2G_2-manifolds with almost twistorial structures.
method Necessary and sufficient conditions derived through Penrose-Ward transformation.
result Conditions for Penrose-Ward transformation on almost G2G_2-manifolds with almost twistorial structures.

The study classifies h-almost Ricci-Yamabe solitons in various paracontact manifolds.

problem Classifying h-almost Ricci-Yamabe solitons in paracontact geometry.
method Characterization and classification of para-Kenmotsu, para-Sasakian, and para-cosymplectic manifolds.
result Characterizations and classifications of various paracontact manifolds.

Study almost rigidity of super Ricci flow with non-negative Muller quantity.

problem Almost rigidity properties of super Ricci flow with non-negative Muller quantity.
method Almost splitting and quantitative stratification theorems established by Bamler for Ricci flow.
result Obtained almost constancy for a certain integral quantity concerning scalar curvature at an almost self-similar point.

Almost para-Hermitian manifold it is manifold equipped with almost para-complex structure and compatible pseudo-metric of neutral signature. It is considered a class of immersions of almost para-Hermitian manifolds into almost para-Hermitian manifolds. Such immersions are called slant submanifolds. The concept is an an…

2017-10-03abs ↗pdf ↗