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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.

168,742 papers · 148 categories

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124248372496 · May 202619922001200920172026
48 results for isotropic structure

Parallel spinors help characterize G2* structures and isotropic forms.

problem Characterizing G2* structures and isotropic forms on pseudo-Riemannian manifolds.
method Using a correspondence between irreducible parallel spinors and solutions of a differential system for three-forms.
result Explicit description of isotropic irreducible spinors in signature (4,3) and characterization of G2* structures.

Study closed G2-structures with T3-symmetry, classifying them into types and deriving hypersymplectic structures.

problem Classify closed G2-structures with T3-symmetry and derive associated hypersymplectic structures.
method Decompose G2-structures into canonical forms, classify structures based on orbit isotropy, and derive hypersymplectic structures.
result Closed G2-structures with T3-symmetry are classified into two types, leading to specific hypersymplectic structures.

We define integrable, big-isotropic structures on a manifold MM as subbundles ETMTME\subseteq TM\oplus T^*M that are isotropic with respect to the natural, neutral metric (pairing) gg of TMTMTM\oplus T^*M and are closed by Courant brackets (this also implies that [E,Eg]Eg[E,E^{\perp_g}]\subseteq E^{\perp_g}). We give the interp…

2006-10-17abs ↗pdf ↗

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.

We consider real isotropic geodesics on manifolds endowed with a pseudoconformal structure and their applications to the theory of lightlike hypersurfaces on such manifolds, the geometry of four-dimensional conformal structures of Lorentzian type, and a classification of the Einstein spaces.

1998-07-16abs ↗pdf ↗

Given a Dirac subbundle and an isotropic subbundle of a Courant algebroid, we provide a canonical method to obtain a new Dirac subbundle. When the original Dirac subbundle is involutive (i.e., a Dirac structure) this construction has interesting applications, for instance to Dirac's theory of constraints and to the Mar…

2007-02-01abs ↗pdf ↗

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 ↗

The isotropic correlation model explains equity returns better than linear factor models.

problem Understanding the covariance structure of equity returns.
method Developed an isotropic covariance model for equity returns, analyzed empirical data, and compared results to linear factor models.
result The isotropic covariance model provides a better fit to recent equity return data compared to linear factor models.

The geometrical structures (in the sense of E. Cartan) are analyzed which underlie the gravitational radiation phenomenon. Among the results are : - the introduction of the adapted frame bundle to a congruence of isotropic hypersurfaces in a Lorentzian manifold, - the description of the reduced frame bundle which admit…

1997-04-25abs ↗pdf ↗

We investigate the local structure of four-dimensional Lorentzian quasi-Einstein manifolds under conditions on the Weyl tensor. We show that if the Weyl tensor is harmonic and the potential function preserves this harmonicity then, in the isotropic case, the manifold is necessarily a pppp-wave. Using the quasi-Einstein…

2019-05-09abs ↗pdf ↗

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.

The authors study the geometry of lightlike hypersurfaces on a four-dimensional manifold (M,c)(M, c) endowed with a pseudoconformal structure c=CO(2,2)c = CO (2, 2). They prove that a lightlike hypersurface V(M,c)V \subset (M, c) bears a foliation formed by conformally invariant isotropic geodesics and two isotropic distributions ta…

1999-02-24abs ↗pdf ↗

We describe the local structure of self-dual gradient Ricci solitons in neutral signature. If the Ricci soliton is non-isotropic then it is locally conformally flat and locally isometric to a warped product of the form I×φN(c)I\times_\varphi N(c), where N(c)N(c) is a space of constant curvature. If the Ricci soliton is isotro…

2014-10-31abs ↗pdf ↗

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.

Proposes Gaussian process priors on graph sets with geometric structure.

problem Defining Gaussian process priors on sets of graphs with geometric structure.
method Defines priors respecting graph geometric structure, analogous to Euclidean isotropic processes.
result Efficient computational technique for evaluating priors' kernels, making them usable in toolboxes.

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.

Derive new Euler-Ramanujan-type identities and infinite decompositions for zero mean curvature graphs in various spaces.

problem Derive new Euler-Ramanujan-type identities and infinite decompositions for zero mean curvature graphs in various spaces.
method Derive new Euler-Ramanujan-type identities and infinite decompositions for zero mean curvature graphs in various spaces.
result Derive new Euler-Ramanujan-type identities and infinite decompositions for zero mean curvature graphs in various spaces.

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.