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.
In the Friedmann Model of the universe, cosmologists assume that spacelike slices of the universe are Riemannian manifolds of constant sectional curvature. This assumption is justified via Schur's Theorem by stating that the spacelike universe is locally isotropic. Here we define a Riemannian manifold as almost locally…
We show that no exotic R4 admits a complete Riemannian metric with uniformly positive isotropic curvature and with bounded geometry. This is essentially a corollary of the main result in [Hu1], and was stated in [Hu2] without proof. In the process of the proof we also show that the diffeomorphism type of an…
In this paper, we find a condition on (α,β)-metrics under which the notions of isotropic S-curvature, weakly isotropic S-curvature and isotropic mean Berwald curvature are equivalent.
We study two types of isotropic planes: weakly isotropic and strongly isotropic planes. We prove that a Riemannian manifold of indefinite metric is conformally flat if and only if its curvature tensor vanishes on all the strongly isotropic planes. We specialize the plane axiom for Riemannian manifolds of indefinite met…
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…
The paper approximates smooth isotropic surfaces with piecewise linear ones.
problem Approximating smooth isotropic surfaces with piecewise linear ones.
method Using analogies with infinite dimensional moment map geometry, the authors prove the approximation of smooth isotropic immersions by piecewise linear ones.
result Smooth isotropic immersions can be approximated by piecewise linear isotropic maps.
In this paper we will show that a Lagrangian, Lorentzian surface M12 in a complex pseudo space form M12(4c) is pseudo-isotropic if and only if M is minimal. Next we will obtain a complete classification of all Lagrangian, Lorentzian surfaces which are lightlike pseudo-isotropic but not pseudo-isot…
We show that for m>n≥2, there are at least two exact isotropic n-tori in Cm which are not Hamiltonian isotopic in Cm, even though they are smoothly isotopic as isotropic n-tori. We apply this discovery to obtain more distinct non-exact isotropic tori in Cm.
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…
We classify translation surfaces in isotropic geometry with arbitrary constant isotropic Gaussian and mean curvature under the condition that at least one of translating curves lies in a plane.
Let Rn+1,n be the vector space R2n+1 equipped with the bilinear form (X,Y)=XtCnY of index n, where Cn=∑i=12n+1(−1)n+i−1ei,2n+2−i. A smooth γ:R→Rn+1,n is {\it isotropic} if γ,γx,…,γx(2n) are linearly independent and the span of γ,…,γx(n−1) is …
Using an integrable discrete Dirac operator, we construct a discrete version of the Weierstrass representation of time-like surfaces parametrized along isotropic directions in R2,1, R3,1 and R2,2. The corresponding discrete surfaces have isotropic edges. We show that any discrete surface satisfying a gen…
The paper classifies almost isotropic Kähler manifolds, proving their properties.
problem Classifying almost isotropic Kähler manifolds.
method Analyzing Jacobi operators and their ranks.
result Almost isotropic Kähler manifolds of dimension d=2n≥4 are isometric to complex projective space, complex hyperbolic space, or totally geodesically foliated by leaves isometric to Cn−1.
In this paper, we study the second approximate Matsumoto metric on a manifold M. We prove that F is of scalar flag curvature and isotropic S-curvature if and only if it is isotropic Berwald metric with almost isotropic flag curvature.
Totally isotropic surfaces in S6 are not necessarily Willmore surfaces. Therefore it is the first goal of this paper to derive a geometric characterization of totally isotropic Willmore two-spheres in S6. This will naturally yield to a description of such surfaces in terms of the loop group language. Moreover, ap…
The isotropic 3-space I^3 which is one of the Cayley--Klein spaces is obtained from the Euclidean space by substituting the usual Euclidean distance with the isotropic distance. In the present paper, we give several classifications on the surfaces in I^3 with the constant relative curvature (analogue of the Gaussian cu…