Study small-time fluctuations for sub-Riemannian diffusion loops.
problem Analyzing fluctuations of sub-Riemannian diffusion processes.
method Analyzes small-time fluctuations of diffusion processes with sub-Riemannian structure, identifying degenerate and non-degenerate covariance matrices.
result Rescaled fluctuations converge to a non-degenerate limiting diffusion loop.
New C-connection characterizes 4D spaces conformal to Einstein spaces.
problem Characterizing 4D spaces conformal to Einstein spaces.
method Introducing C-connection, a Weyl connection that preserves conformal invariance. result Characterizes non-degenerate spaces conformal to Einstein spaces.
Paper estimates GMMs with unknown covariances using sparse regularization.
problem Estimating GMMs with unknown diagonal covariances from samples.
method Employed Beurling-LASSO (BLASSO) for sparse estimation of component means, covariances, and weights.
result Established non-asymptotic recovery guarantees with nearly parametric convergence rates.
Superintegrable systems on surfaces are classified geometrically.
problem Classifying superintegrable systems on conformal surfaces.
method Geometric structures on conformal surfaces, conformal covariant structural equations.
result Explicit set of algebraic equations defining superintegrable systems on all constant curvature surfaces.
Paper explores how design matrix patterns affect regression performance in over-parameterized models.
problem The impact of covariance matrix degeneracy and covariate dependence on regression performance in over-parameterized models.
method Derives deterministic equivalents for prediction risk in a vanishing-ridge regime, using graph theory to identify singular configurations.
result Degeneracy of covariance matrices and dependence can lead to multiple descent in regression performance.
Study on neural network initialization with shaped infinite depth-and-width networks.
problem Understanding the distribution of random covariance matrices in shaped infinite-depth-and-width networks.
method Introduced the Neural Covariance SDE to model the distribution of the random covariance matrix.
result Identified the precise scaling of the activation function necessary for a non-trivial limit.
A unified framework for Poisson and Jacobi structures from 2-covariant tensors
problem Constructing Poisson and Jacobi structures from non-degenerate 2-covariant tensors
method Deriving a formula for the Schouten-Nijenhuis bracket of the associated bivector field
result Recovering classical brackets associated with symplectic, locally conformally symplectic, cosymplectic, and contact geometries
Classifies homogeneous Levi non-degenerate hypersurfaces in complex 3-space.
problem Classifying specific types of complex hypersurfaces.
method Analyzing hypersurfaces with symmetry algebra of dimension at least 6.
result All such hypersurfaces are classified.
Bayesian framework improves robustness in nonlinear regression models.
problem Measurement error, model misspecification, and distributional misspecification in regression analyses.
method Joint Dirichlet process prior on latent covariate-response distribution, updating with posterior pseudo-samples.
result Improved stability and consistency in estimators under increasing measurement error.
On a Riemannian or a semi-Riemannian manifold, the metric determines invariants like the Levi-Civita connection and the Riemann curvature. If the metric becomes degenerate (as in singular semi-Riemannian geometry), these constructions no longer work, because they are based on the inverse of the metric, and on related o…
I-non-degenerate spaces are spacetimes that can be characterized uniquely by their scalar curvature invariants. The ultimate goal of the current work is to construct a basis for the scalar polynomial curvature invariants in three dimensional Lorentzian spacetimes. In particular, we seek a minimal set of alg…
Study on hypersurfaces with minimized distance between rulings.
problem Characterizing singularities and properties of two-ruled hypersurfaces.
method Characterization through striction curves and examination of pseudo-non-degenerate properties.
result Two-ruled hypersurfaces constructed from specific curves are pseudo-non-degenerate.
New proof shows certain 4D metrics are non-degenerate if curvature is negative definite.
problem Proving non-degeneracy of Poincaré-Einstein metrics.
method Proved non-degeneracy for 4D metrics satisfying a chiral curvature inequality.
result 4D Poincaré-Einstein metrics are non-degenerate if curvature is negative definite.
Theorem shows generic metrics yield non-degenerate geodesic nets.
problem Characterizing geodesic nets on generic metrics.
method Proving all connected embedded nets are non-degenerate for Baire-generic metrics.
result All stationary geodesic nets are non-degenerate for generic metrics.
New move proves infinitely many non-conjugate braids for certain links.
problem Proving infinitely many non-conjugate braids for certain link types.
method Introducing a non-degenerate exchange move.
result Links have infinitely many non-conjugate braids after applying the move.
Develops new Poisson structures for moduli spaces.
problem Creating Poisson structures for moduli spaces.
method Introduces quasi Poisson and quasi Hamiltonian structures, novel momentum mappings.
result Bijective correspondence between quasi Poisson and quasi Hamiltonian structures.
We show that non-degenerate hyperquadrics in R^{n+2} admit no skew branes. Stated more traditionally, a compact codimension-one immersed submanifold of a non-degenerate hyperquadric of euclidean space must have parallel tangent spaces at two distinct points. Similar results have been proven by others, but (except for e…
Consider a d×d matrix M whose rows are independent centered non-degenerate Gaussian vectors ξ1,...,ξd with covariance matrices Σ1,...,Σd. Denote by Ei the location-dispersion ellipsoid of ξi:Ei=x∈Rd:x⊤Σi−1x⩽1. We sh…
The study resolves a conjecture about harmonic forms on compact manifolds.
problem Finding non-degenerate Z2-harmonic 1-forms on compact manifolds. method Develops a gluing theorem for non-degenerate Z2-harmonic 1-forms on compact manifolds. result Proves the existence of non-degenerate Z2-harmonic 1-forms on compact manifolds with positive first Betti number. Study on singularities of specific polynomial functions.
problem Characterizing the topology of singularities of mixed functions.
method Introduced inner non-degenerate mixed functions and used Newton boundary to characterize links.
result Links of singularities can be completely characterized under certain conditions.
The paper classifies almost complex manifolds with non-degenerate torsion and their coverings.
problem Classification of almost complex manifolds with non-degenerate torsion.
method Analysis of homogeneous and non-homogeneous manifolds, classification of Lie algebras, covering spaces.
result Classification of manifolds with solvable Lie algebra up to coverings.
The abstract discusses transformations on statistical and semi-Weyl manifolds with torsion.
problem Invariance and structure preservation under conformal-projective transformations.
method Proof of invariance and preservation of structures under conformal-projective transformations.
result Semi-Weyl and statistical structures with torsion are invariant under conformal-projective transformations.
New findings on non-congruent curves with identical signatures.
problem Identifying congruence of non-degenerate curves with non-simple signatures.
method Associated directed graphs to signatures and used paths to reflect global and local symmetries.
result Non-congruent, non-degenerate curves can have identical signatures.
Researchers create non-degenerate harmonic functions on n-dimensional space.
problem Creating non-degenerate Z2-harmonic functions on Rn. method Using a variant of ellipsoidal coordinates, the construction is explicit and involves Lawlor's necks in Cn. result First known family of non-degenerate Z2-harmonic 1-forms with compact branching sets. The paper identifies all flat CR Lie groups and their structures.
problem Identifying flat CR Lie groups and their structures.
method Analyzing Lie algebras and structures of Lie groups.
result Only specific Lie algebras are Cartan flat non-degenerate CR Lie algebras.
Classifies 3D non-degenerate left-symmetric algebras.
problem Classifying left-symmetric algebras in 3D.
method Using Nijenhuis geometry and algebraic independence of coefficients in characteristic polynomial.
result Classification of differentially non-degenerate LSA in dimension 3.
Paper studies invariant distributions of bi-Hamiltonian structures.
problem Integrability of invariant distributions in bi-Hamiltonian structures.
method Description and investigation of invariant distributions.
result All invariant distributions of non-degenerate bi-Hamiltonian structures are described.
A new data-adaptive prior stabilizes kernel learning in operators.
problem Learning kernels in operators from data is ill-posed due to nonlocal dependence.
method Introduces a data-adaptive prior to stabilize the Bayesian posterior mean.
result The data-adaptive prior achieves a stable posterior with small noise limits.
We extend the Bismut-Elworthy-Li formula to non-degenerate jump diffusions and "payoff" functions depending on the process at multiple future times. In the spirit of Fournie et al [13] and Davis and Johansson [9] this can improve Monte Carlo numerics for stochastic volatility models with jumps. To this end one needs so…
Study non-degenerate anisocurved surfaces in homogeneous 3-manifolds.
problem Compare and study surfaces with opposite Gaussian curvatures under two different metrics.
method Consider surfaces in homogeneous 3-manifolds with two metrics, impose extrinsic curvature conditions, and analyze Gaussian curvature functions.
result Identify and characterize anisocurved surfaces with opposite Gaussian curvatures under both metrics.
Bayesian deep neural networks converge to processes with α-stable marginals under infinite variance weights.
problem Representation learning in deep kernel processes is hindered by deterministic covariance kernels.
method Showed convergence to α-stable processes with conditionally Gaussian representations in infinite-width networks.
result Conditional random covariance kernels can be recursively linked, even if the process is α-stable.
Paper describes links of mixed polynomials with specific properties.
problem Understanding the links of mixed polynomials with nice Newton boundaries.
method Analyzes links constructed from sequences of links associated with compact 1-faces of the Newton boundary.
result Links of singularities of inner non-degenerate mixed polynomials can be described using a specific procedure.
Study transverse metric expansion on null hypersurfaces, proving uniqueness for Killing horizons.
problem Analyzing transverse expansion of metric on null hypersurfaces.
method Covariant approach, general geometric identities, generalized symmetry generators.
result Transverse expansion of spacetime metric uniquely determined at non-degenerate Killing horizons.
The paper proves uniform stable radius and Milnor number equality for specific mappings.
problem Proving uniform stable radius and Milnor number equality for specific mappings.
method Analytic family construction and Newton polyhedra analysis.
result Milnor numbers of non-degenerate isolated complete intersection singularities are equal.
We give complete classification of C^2-regular and non-degenerate projectively Anosov flows on three dimensional manifolds. More precisely, we prove that such a flow on a connected manifold must be either an Anosov flow or represented as a finite union of T2×[0,1]-models.
Proves ideal triangulations of hyperbolic alternating links are non-degenerate.
problem Proving ideal triangulations of hyperbolic alternating links are non-degenerate.
method Using non-positively curved cubings of prime alternating link exteriors.
result Ideal triangulations are non-degenerate, guaranteeing hyperbolicity equations have solutions.
New classification of complex hypersurfaces in 3D.
problem Classifying simply-transitive Levi non-degenerate hypersurfaces in C3. method Novel Lie algebraic approach, new coordinate-free formula for quartic tensor.
result Unique non-tubular model with geometric relations to planar equi-affine geometry.
Study on symmetric CR geometries of hypersurface type, showing they are either flat or homogeneous.
problem Characterizing symmetric CR geometries of hypersurface type.
method Analyzing CR transformations and symmetries, constructing examples.
result Non-flat non-degenerate symmetric CR geometries of hypersurface type are either flat or homogeneous.
Let M be a connected, non-compact m-dimensional Riemannian manifold. In this paper we consider smooth maps φ:M→Rn with images inside a non-degenerate cone. Under quite general assumptions on M, we provide a lower bound for the width of the cone in terms of the energy and the tension of φ and a …
New insights into black hole horizons from asymptotic expansions.
problem Understanding the geometry of black hole horizons.
method Proving the asymptotic expansion of spacetime metrics at non-degenerate Killing horizons.
result The full asymptotic expansion of smooth vacuum metrics at non-degenerate Killing horizons is determined by the horizon geometry.
In this paper we study lightlike surfaces of Minkowski 3- space such that they have degenerate or non-degenerate planar normal sections. We first show that every lightlike surface of Minkowski 3− space has degenerate planar normal sections. Then we study lightlike surfaces with non-degenerate planar normal sections a…
Classification of homogeneous almost complex 4-manifolds with non-degenerate torsion bundle
problem Classification of homogeneous almost complex 4-manifolds with non-degenerate torsion bundle
method Classification using rigidity of structures
result Complete classification in the homogeneous setting
Desingularizes Einstein metrics with A1 singularities in 4D.
problem Desingularizing Einstein metrics with specific singularities.
method Recursive procedure to desingularize Fuchsian singularities.
result Desingularizations of non degenerate Poincaré-Einstein metrics with A1 singularities remain non degenerate.
We obtain an explicit parametrization of stationary discs glued to some Levi non-degenerate hypersurfaces. These discs form a family which is invariant under the action of biholomorphisms. We use this parametrization to construct a local circular representation of these hypersurfaces. As a corollary, we get the uniquen…
New operators defined on supermanifolds, linked to Darboux transformations.
problem Defining and analyzing differential operators on supermanifolds.
method Defining non-degenerate operators, using super Wronskians and Berezinians, applying Darboux transformations.
result Every Darboux transformation corresponds to an invariant subspace and can be expressed by a super-Wronskian formula.
This paper introduces a new homology theory for Yang-Baxter solutions.
problem Defining a homology theory for set-theoretic Yang-Baxter solutions.
method Introducing normalized homology theory and proving its split into parts.
result Set-theoretic Yang-Baxter homology can be split into normalized and degenerated parts.
We study an infinite dimensional ASD moduli space over the cylinder. Our main result is the formula of its local mean dimension. A key ingredient of the argument is the notion of non-degenerate ASD connections. We develop its deformation theory and show that there exist sufficiently many non-degenerate ASD connections …
In this article, we demonstrate methods for the local removal and modification of complex tangents to embeddings of S3 into C3. In particular, given any embedding of S3 and a neighborhood of the complex tangents of the embedding, we show that there exists a (C0-close) totally real embedding which a…