We realise the first and second Grushin distributions as symmetry reductions of the 3-dimensional Heisenberg distribution and 4-dimensional Engel distribution respectively. Similarly, we realise the Martinet distribution as an alternative symmetry reduction of the Engel distribution. These reductions allow us to derive…
Study solves ∞(x)-equation in Grushin spaces using adapted jets.
problem Solving ∞(x)-equation in Grushin-type spaces. method Used Grushin jets adapted to Grushin-type spaces' geometry.
result Existence and uniqueness of viscosity solutions.
Study sub-Finsler geometry in time-optimal control for specific distributions.
problem Characterize optimal paths in sub-Finsler geometry for non-smooth, non-convex structures.
method Time-optimal control approach for Heisenberg, Grushin, and Martinet distributions.
result Extremal curves are Euclidean rectifiable and optimal.
Computed distortion coefficients for the α-Grushin plane.
problem Analyzing the distortion coefficients of the α-Grushin plane.
method Using generalised trigonometric functions and synthetic curvature conditions.
result Estimates for distortion coefficients and a curvature condition conjecture.
Researchers create metrics on spheres with Ricci curvature ≥1, limiting to Grushin hemisphere.
problem Constructing metrics with Ricci curvature ≥1 on spheres.
method Sequence of Riemannian metrics on Sm+n with Ric≥1. result Gromov-Hausdorff limit of the sequence is the Grushin hemisphere.
Study on quantum particle evolution on Grushin cylinder, embedding in R^3.
problem Understanding quantum particle behavior on Grushin cylinder.
method Intrinsic and extrinsic quantizations, embedding in R^3.
result Formulas to embed Grushin cylinder in R^3, useful for other purposes.
Bi-Lipschitz embedding of a generalized Grushin plane in Euclidean space.
problem Embedding a generalized Grushin plane in Euclidean space.
method Bi-Lipschitz homeomorphic embedding in R[α]+2. result Generalized Grushin plane is bi-Lipschitz homeomorphic to a 2-dimensional quasiplane.
New cylindrical solutions found for Grushin-type problem.
problem Critical Grushin-type problem on CR sphere.
method Local Pohozaev identities for non-degeneracy, Lyapunov-Schmidt reduction for solutions.
result New type of multi-bubbling cylindrical solutions constructed.
Research finds double bubbles in Grushin plane with specific geometric properties.
problem Addressing double bubble problem in Grushin plane with anisotropic perimeter.
method Existence via direct method and characterization via first variation techniques.
result Angles at intersections satisfy 120-degree rule, with differences for α=0 and α=1.
The study examines optimal synthesis in a radially symmetric Grushin space with conditions on the weight function.
problem Optimal synthesis in a radially symmetric Grushin space with a weight function.
method Analysis of the geometry of R3 with a weighted Carnot-Carathéodory metric, providing conditions for Grushin-like structure, and describing optimal synthesis. result Sufficient conditions on the weight function ensure a Grushin-like structure, and the candidate cut time coincides with the true cut time in the integrable case.
Fundamental solutions found for p-Laplace equations in Heisenberg and Grushin spaces.
problem Finding solutions to p-Laplace equations with drift terms in specific geometric spaces.
method Analyzing fundamental solutions in the Heisenberg group and Grushin-type planes.
result Natural generalizations of Beals, Gaveau, and Greiner's solutions for the Laplace equation with drift term.
Study geodesics on Grushin spaces, proving upper bounds on conjugate times.
problem Classify geodesics on higher-dimensional Grushin spaces.
method Solve Hamilton's equations using calculus of generalized trigonometric functions, analyze symmetries, and use density arguments.
result Prove a conjectured cut time provides an upper bound on conjugate times.
Study geometric quantum confinement on special incomplete Riemannian manifolds.
problem Characterize quantum confinement on Grushin-type manifolds.
method Constant-fibre direct integral scheme combined with Weyl's analysis.
result Fully characterizes essential self-adjointness of Laplace-Beltrami operator.
New sub-Riemannian spaces with boundary meet curvature-dimension condition.
problem Finding sub-Riemannian manifolds with boundary satisfying curvature-dimension condition.
method Constructing specific sub-Riemannian structures on half-spaces and hemispheres.
result Provided new examples of sub-Riemannian manifolds with boundary that meet RCD(K,N) condition. The paper explores self-adjointness of Laplace-Beltrami operator on special geometric manifolds.
problem Characterizing self-adjoint extensions of the Laplace-Beltrami operator on α-Grushin manifolds. method Introducing an exotic calculus of pseudodifferential operators adapted to the geometry of the singularity.
result Criterion for essential self-adjointness and determination of several self-adjoint extensions.
Classifies quantum particle behavior on a special cylinder.
problem Quantum confinement and transmission on a Grushin cylinder.
method Characterizes self-adjoint realizations of the Laplace-Beltrami operator.
result Identifies physically meaningful extensions of the Hamiltonian.
This article deals with 2d almost Riemannian structures, which are generalized Riemannian structures on manifolds of dimension 2. Such sub-Riemannian structures can be locally defined by a pair of vector fields (X,Y), playing the role of orthonormal frame, that may become colinear on some subset. We denote D = span(X,Y…
Study shows failure of curvature-dimension conditions on sub-Riemannian manifolds.
problem Failure of curvature-dimension conditions on sub-Riemannian manifolds.
method Proves failure of curvature-dimension conditions using tangent isometries and Killing vector fields.
result Proves failure of curvature-dimension conditions on sub-Riemannian manifolds.
The Heston model is a popular stock price model with stochastic volatility that has found numerous applications in practice. In the present paper, we study the Riemannian distance function associated with the Heston model and obtain explicit formulas for this function using geometrical and analytical methods. Geometric…
Counterexample disproves gluing theorem for MCP metric spaces.
problem Gluing theorems for MCP metric measure spaces are not universally valid.
method Used Grushin half-plane as a counterexample.
result The doubling of Grushin half-plane does not satisfy MCP(0,N) for all N.
Study on heat flow across two half-lines with special boundary conditions.
problem Low energy mode of heat flow transmission across a Grushin-type cylinder.
method Analysis of heat equation with inverse-square potential and bridging boundary conditions.
result First insight into qualitative features of the heat flow solution at later times.
The study proves sub-Riemannian manifolds cannot satisfy CD conditions unless they are Riemannian.
problem Characterizing sub-Riemannian manifolds that satisfy CD conditions. method Analysis of tangent cones and geodesics, construction of new RCD structures. result Sub-Riemannian manifolds are never CD(K,N) unless they are Riemannian. We study Monge's optimal transportation problem, where the cost is given by optimal control cost. We prove the existence and uniqueness of an optimal map under certain regularity conditions on the Lagrangian, absolute continuity of the measures with respect to Lebesgue, and most importantly the absence of sharp abnorma…
Extensions of Brownian motion to singular surfaces are studied.
problem Diffusion across singularities on surfaces.
method One-parameter family of Grushin-type singularities, heat crossing analysis, isometry group respect, Bessel processes.
result Complete description and classification of diffusions for various singularity cases.
New Weyl's laws discovered for compact spaces with Ricci curvature bounds.
problem Understanding growth rates of eigenvalues in compact spaces with Ricci curvature constraints.
method Developed new properties of α-Grushin halfplanes and analyzed singular sets of null capacities. result Established Weyl's laws with power growth and logarithmic corrections for compact spaces.
We prove a classification theorem for conformal maps with respect to the control distance generated by a system of diagonal vector fields. It turns out that all such maps can be obtained as compositions of suitable dilations, inversions and isometries. We also classify all umbilical surfaces of the underlying metric.
Paper studies viscosity solutions in unique Martinet spaces.
problem Properties of viscosity solutions in Martinet spaces.
method Established properties and proved uniqueness of solutions.
result Uniqueness of viscosity solutions in Martinet spaces.
New theorem on embedding Moebius bands in 3D space.
problem Proving the impossibility of placing uncountably many disjoint Moebius bands in 3D space.
method Generalization of Grushin and Palamodov's result to tame subsets in R^N and arbitrary topological embeddings in R^3.
result The impossibility of embedding uncountably many pairwise disjoint Moebius bands in 3D space, even for arbitrary topological embeddings.
Researchers solve p-Laplace equation in Hörmander vector fields.
problem Finding fundamental solution in specific vector field class.
method Used generalized operator in Euclidean space to find solution.
result Computed capacity of annuli centered at singularity.
Generalizes Cheeger inequality to Carnot-Carathéodory spaces.
problem Lower bounds on eigenvalues of Laplacians in complex spaces.
method Geometric approach, including Neumann and mixed boundary conditions.
result Concrete method to lower bound Cheeger constant.
New trigonometric method for convex sets aids control problems.
problem Optimal control problems with two-dimensional control.
method Proposes a new method to describe convex sets.
result Investigates sub-Finsler problems in various groups.
We study spectral properties of the Laplace-Beltrami operator on two relevant almost-Riemannian manifolds, namely the Grushin structures on the cylinder and on the sphere. This operator contains first order diverging terms caused by the divergence of the volume. We get explicit descriptions of the spectrum and the eige…
Ideal sub-Riemannian manifolds support interpolation inequalities for optimal transport.
problem Optimal transport on sub-Riemannian manifolds.
method Sub-Riemannian Jacobi fields and distortion coefficients.
result Ideal sub-Riemannian manifolds support interpolation inequalities.
The paper uses singularity theory to find normal forms for sub-Riemannian exponential maps.
problem Finding normal forms near critical points of sub-Riemannian exponential maps.
method Singularity theory applied to sub-Riemannian structures.
result Normal forms for sub-Riemannian exponential maps in specific cases.
Study spectral properties of sub-Riemannian Laplacians, proving quantum ergodicity and heat kernel asymptotics.
problem Spectral properties of sub-Riemannian Laplacians.
method Quantum ergodicity results, small-time asymptotics of sub-Riemannian heat kernels, Weyl law.
result Weyl law and spectral concentration on Lie brackets of length r-1.
For a sub-Riemannian manifold provided with a smooth volume, we relate the small time asymptotics of the heat kernel at a point y of the cut locus from x with roughly "how much" y is conjugate to x. This is done under the hypothesis that all minimizers connecting x to y are strongly normal, i.e.\ all pieces…
We establish a Harnack inequality for a class of quasi-linear PDE modeled on the prototype {equation*} \partial_tu= -\sum_{i=1}^{m}X_i^\ast (|\X u|^{p-2} X_i u){equation*} where p≥2, $ \ \X = (X_1,..., X_m)$ is a system of Lipschitz vector fields defined on a smooth manifold $\M$ endowed with a Borel measure μ, …
Two-dimensional almost-Riemannian structures are generalized Riemannian structures on surfaces for which a local orthonormal frame is given by a Lie bracket generating pair of vector fields that can become collinear. Generically, the singular set is an embedded one dimensional manifold and there are three type of point…
Quantitative estimates for inequalities on sub-Riemannian manifolds.
problem Quantitative estimates for Lp-Poincaré and log-Sobolev inequalities on sub-Riemannian manifolds. method Introducing the Quasi Curvature-Dimension condition and applying it to various sub-Riemannian manifolds.
result Established quantitative estimates independent of the dimension on various sub-Riemannian manifolds.
The paper explores solutions to the distributional Bellman equation in reinforcement learning.
problem Distributional reinforcement learning considers complete return distributions, not just expected returns.
method Study existence and uniqueness of solutions to general distributional Bellman equations, linking them to multivariate affine equations.
result Any solution to a distributional Bellman equation can be derived from a multivariate affine distributional equation.
Proposes vMF distribution for skewed elliptical distributions.
problem Skewed distributions not adequately modeled by symmetric distributions.
method Introduces von-Mises-Fisher (vMF) distribution to represent skewed elliptical distributions.
result vMF distribution provides an explicit and simple probability representation of skewed elliptical distributions.
This paper examines how the choice of prior distribution affects likelihoods of out-of-distribution inputs in deep generative models.
problem Mismatch between prior and data distributions causes deep generative models to assign higher likelihoods to out-of-distribution inputs.
method Proposes using a mixture distribution as a prior to make likelihoods of out-of-distribution inputs more sensitive.
result A mixture prior lowers the out-of-distribution likelihood with respect to real image data sets.
Study calculates tail risk for various mixture distributions.
problem Estimating tail risk for complex distribution mixtures.
method Analyzes tail conditional expectation for location-scale mixtures of elliptical distributions.
result Developed methods for calculating tail risk in various distributions.
No stable distributions found in financial data, study shows.
problem Use of heavy tailed distributions in finance is questioned.
method Analysis of financial indexes and observed outliers.
result Stable distributions like Cauchy do not fit real financial data.
New constrained mixtures create asymmetric distributions for better modeling.
problem Creating better models for asymmetric data.
method Introducing constrained mixtures to create generalized asymmetric versions of continuous distributions.
result Asymmetric distributions provide higher likelihood and less entropy in real-world applications.
New wealth distribution model based on κ-deformation of Gamma distribution.
problem Modeling wealth distribution in heterogeneous kinetic exchange models.
method Proposed a new four-parameter statistical distribution based on κ-deformation of the Generalized Gamma distribution. result The new distribution accurately represents wealth distribution in heterogeneous kinetic exchange models.
This study suggests replacing Ising distribution with Cox distribution.
problem Handling correlated binary data efficiently.
method Exploring conditions for replacing Ising distribution with Cox distribution as a latent variable model.
result The Ising distribution can be treated as a latent variable model with a quasi-normal distribution.
New algorithms for learning under s-concave distributions, including Pareto and t-distributions.
problem Learning under broad and natural generalizations of log-concave distributions, including fat-tailed ones.
method Introduce new convex geometry tools to study s-concave distributions and use these properties to provide bounds on learning quantities. result Significantly generalize prior results for margin-based, disagreement-based, and passive learning of intersections of halfspaces.