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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.

168,695 papers · 148 categories

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8162331 · Oct 202519922001200920172026
48 results for isotropic spacetime

Study isotropic solutions in smooth metric measure spaces with vacuum Einstein equations.

problem Investigate isotropic solutions in smooth metric measure spaces under vacuum Einstein field equations.
method Define a weighted Einstein tensor and associated vacuum field equations. Analyze solutions for different spacetime types.
result Isotropic solutions have nilpotent Ricci operator and specific forms in 2- and 3-step nilpotent manifolds.

Geodesic completeness and flow properties of compact Brinkmann spacetimes proven.

problem Geodesic completeness and flow properties of compact Brinkmann spacetimes.
method Proof of geodesic completeness and flow properties of isotropic parallel vector fields in compact Brinkmann spaces.
result Geodesic completeness and flow properties of compact Brinkmann spacetimes proven.

New findings show cosmological constant as initial condition for non-isotropic spacetimes.

problem Cosmological constant as initial condition in non-isotropic spacetimes.
method Generalized previous results to non-isotropic spacetimes.
result Quasi de Sitter expansion for early universe, potential for inflationary scenarios.

The paper investigates the singularity and extendibility of inflationary spacetimes.

problem The existence and extendibility of initial curvature singularities in inflationary spacetimes.
method Classification and rigorous extendibility criteria derivation for quasi-de Sitter spacetimes.
result Past-eternal inflationary scenarios are most likely physically singular, except in very special initial conditions.

Classifies cosmological Finsler spacetimes, finding viable non-stationary models.

problem Locating viable non-stationary Finsler spacetimes in cosmology.
method Locally classified all possible cosmological homogeneous and isotropic Landsberg-type Finsler structures in 4-dimensions.
result Identified unique Finsler, non-Berwaldian Landsberg generalization of Friedmann-Lemaitre-Robertson-Walker geometry.

Photon surfaces are timelike, totally umbilic hypersurfaces of Lorentzian spacetimes. In the first part of this paper, we locally characterize all possible photon surfaces in a class of static, spherically symmetric spacetimes that includes Schwarzschild, Reissner--Nordström, Schwarzschild-anti de Sitter, etc., in $n+1…

2019-10-09abs ↗pdf ↗

In this work we study Berwald spacetimes and their vacuum dynamics, where the latter are based on a Finsler generalization of the Einstein's equations derived from an action on the unit tangent bundle. In particular, we consider a specific class of spacetimes which are non-flat generalizations of the very special relat…

2018-04-25abs ↗pdf ↗

We classify simply-connected homogeneous (D+1D+1)-dimensional spacetimes for kinematical and aristotelian Lie groups with DD-dimensional space isotropy for all D0D\geq 0. Besides well-known spacetimes like Minkowski and (anti) de Sitter we find several new classes of geometries, some of which exist only for D=1,2D=1,2. Th…

2018-09-04abs ↗pdf ↗

Overview of marginally trapped surfaces in various spacetimes.

problem Understanding marginally trapped surfaces in different spacetimes.
method Differential geometric study of marginally trapped surfaces in Minkowski, de Sitter, anti-de Sitter, and Robertson-Walker spacetimes.
result General local descriptions and classifications of these surfaces.

Study on generalized mm-Kropina metrics in modified gravity and cosmology.

problem Understanding the geometric properties and applications of generalized mm-Kropina metrics.
method Proving the rationality of Finslerian geometric objects and studying the conditions for Einstein metrics.
result Conditions for a generalized mm-Kropina metric to be an exact solution in modified gravity and cosmology.

The paper examines Randers metrics with isotropic scalar curvature properties.

problem Characterizing Randers metrics with specific scalar curvature properties.
method Analyzes properties of Randers metrics with isotropic scalar curvature.
result Proves that Randers metrics with weakly isotropic scalar curvature have isotropic SS-curvature and are either Minkowskian or Riemannian.

Study physical work done by isotropic vector forces along isotropic curves.

problem Investigate physical work done by isotropic vector forces.
method Analyze forces represented by isotropic vectors acting along isotropic curves on a manifold with specific metric structures.
result Calculate the work done by isotropic vector forces along isotropic curves.

In this paper, we construct a new class of Finsler manifolds called generalized isotropic Berwald manifolds which is an extension of the class of isotropic Berwald manifolds. We prove that every generalized isotropic Berwald manifold is a generalized Douglas-Weyl manifold. On a compact generalized isotropic Berwald man…

2013-02-12abs ↗pdf ↗

Spinor representation in isotropic space via Laguerre geometry.

problem Representing conformal and constant mean curvature surfaces in isotropic space.
method Developing Laguerre geometry of isotropic space, defining spin transformations, and constructing Weierstrass and Kenmotsu representations.
result Explicit constructions of zero mean curvature and constant mean curvature surfaces.

The paper studies hanging chains and surfaces in degenerate geometries.

problem Investigating hanging chains and surfaces in simply isotropic plane and space.
method Characterizing catenaries and proving them as minimal surfaces in the simply isotropic space.
result The simply isotropic catenary is the generating curve of a minimal surface of revolution.

In this paper we will show that a Lagrangian, Lorentzian surface M12M^2_1 in a complex pseudo space form M~12(4c)\widetilde M^2_1 (4c) is pseudo-isotropic if and only if MM is minimal. Next we will obtain a complete classification of all Lagrangian, Lorentzian surfaces which are lightlike pseudo-isotropic but not pseudo-isot…

2016-10-05abs ↗pdf ↗

We show that for m>n2m>n\geq 2, there are at least two exact isotropic nn-tori in Cm\mathbb{C}^m which are not Hamiltonian isotopic in Cm\mathbb{C}^m, even though they are smoothly isotopic as isotropic nn-tori. We apply this discovery to obtain more distinct non-exact isotropic tori in Cm\mathbb{C}^m.

2016-03-30abs ↗pdf ↗

Study classifies zero mean curvature surfaces with planar curvature lines.

problem Characterizing surfaces with specific curvature properties.
method Complete classification and investigation of their relationship to Thomsen-type surfaces.
result Zero mean curvature surfaces with planar curvature lines belong to a 1-parameter family.

The study of Laguerre isotropic hypersurfaces with rigidity and isoparametric properties.

problem Characterizing and understanding Laguerre isotropic hypersurfaces.
method Analyzing hypersurfaces with zero Laguerre form and constant eigenvalues of the Laguerre tensor.
result For L-isotropic hypersurfaces, if they are also L-isoparametric, the constant λλ must be zero.

This paper aims to provide a description of totally isotropic Willmore two-spheres and their adjoint transforms. We first recall the isotropic harmonic maps which are introduced by Hélein, Xia-Shen and Ma for the study of Willmore surfaces. Then we derive a description of the normalized potential (some Lie algebra valu…

2016-04-10abs ↗pdf ↗

Study surfaces with constant ratio of principal curvatures in Euclidean and isotropic geometries.

problem Characterize surfaces with constant ratio of principal curvatures in different geometries.
method Differential geometry, line geometry, Lie sphere geometry, ordinary differential equations, algebraic geometry.
result Characterized various types of surfaces like rotational, channel, ruled, helical, and translational.

This work extends holomorphic surface representations to isotropic space.

problem Representing minimal surfaces in simply isotropic space with degenerate metrics.
method Developed new forms of Weierstrass and Björling representations for isotropic minimal surfaces.
result Holomorphic representations of isotropic minimal surfaces are achieved.

Paper classifies Randers metrics based on Ricci curvature properties.

problem Investigating isotropic projective Ricci curvature in Randers metrics.
method Classification of Randers metrics based on isotropic projective Ricci curvature properties.
result Randers metric of isotropic projective Ricci curvature is reversible if and only if it is of square projective Ricci curvature.

The study finds compact vacuum static spaces with positive isotropic curvature are spheres or products of a circle and sphere.

problem Characterizing compact vacuum static spaces with positive isotropic curvature.
method Proving isometric equivalence to spheres or product spaces.
result Compact vacuum static spaces with positive isotropic curvature are isometric to spheres or product spaces.

Let Rn+1,nR^{n+1, n} be the vector space R2n+1R^{2n+1} equipped with the bilinear form (X,Y)=XtCnY(X,Y)=X^t C_n Y of index nn, where Cn=i=12n+1(1)n+i1ei,2n+2iC_n= \sum_{i=1}^{2n+1} (-1)^{n+i-1} e_{i, 2n+2-i}. A smooth γ:RRn+1,nγ: R\to R^{n+1,n} is {\it isotropic} if γ,γx,,γx(2n)γ, γ_x, \ldots, γ_x^{(2n)} are linearly independent and the span of γ,,γx(n1)γ, \ldots, γ_x^{(n-1)} is …

2016-08-26abs ↗pdf ↗