arXiv research

Defines horocyclic evolutes, parallels, and involutes of spacelike frontals in hyperbolic 2-space.

The paper studies singularities of pedal curves of hyperbolic frontals.

Develops a Thom-Mather theory for corank 1 frontals.

Study of normal and tangent maps to frontals.

The study examines singularities and geometric properties of surfaces derived from frontals with specific singular points.

Abstract: Characterizes frontals and wavefronts with formulas.

The paper extends equiaffine structure to frontals and defines Blaschke vector fields.

Study on singularities of frontal surfaces, classifying under equivalence.

Study behavior of curvatures near singular points of frontals.

The study examines vertices in curves with singular points in the Euclidean plane.

Study helicoidal surfaces with singular points using frontals.

The paper derives new Gauss-Bonnet formulas for frontal bundles over surfaces with boundary.

Characterizes the Legendre involution on generic frontals.

In this survey article we introduce the notion of frontals, which provides a class of generalised submanifolds with singularities but with well-defined tangent spaces. We present a review of basic theory and known studies on frontals in several geometric problems from singularity theory viewpoints. In particular, in th…

Study helicoidal surfaces from frontals, revealing geometric rigidity and stability of singularities.

For Legendre curves, we consider surfaces of revolution of frontals. The surface of revolution of a frontal can be considered as a framed base surface. We give the curvatures and basic invariants for surfaces of revolution by using the curvatures of Legendre curves. Moreover, we give properties of surfaces of revolutio…

The paper studies helicoidal surfaces of non-lightlike frontals in Lorentz-Minkowski 3-space.

This is a survey article on recognition problem of frontal singularities. We specify geometrically several frontal singularities and then we solve the recognition problem of such singularities, giving explicit normal forms. We combine the recognition results by K. Saji and several arguments on openings, which was perfo…

The paper studies singularities on parallels of tangent developable surfaces of frontal curves.

The paper generalizes curvature bounds for submanifolds with singularities.

The paper improves Zakalyukin's lemma for frontals and applies it to surface singularities.

The paper generalizes Fenchel's theorem for curves with singularities.

The MIMIC-CXR dataset is (to date) the largest released chest x-ray dataset consisting of 473,064 chest x-rays and 206,574 radiology reports collected from 63,478 patients. We present the results of training and evaluating a collection of deep convolutional neural networks on this dataset to recognize multiple common t…

Geometric study of cuspidal $S_1$ singularities using diffeomorphisms and isometries.

Let $f: N^n\to \mathbb{R}^{n+1}$ be a frontal with its Gauss mapping $ν: N\to S^n$ and let $P\in \mathbb{R}^{n+1}$ be a point such that $(f(x)-P)\cdot ν(x) \ne 0$ for any $x\in N$. In this paper, for the mapping $\widetilde{f}: N\to \mathbb{R}^{n+1}$ defined by $$ \widetilde{f}(x)=f(x)-\frac{||f(x)-P||^2}{2(f(x)-P) \cd…

In a joint work with Saji, the second and the third authors gave an intrinsic formulation of wave fronts and proved a realization theorem of wave fronts in space forms. As an application, we show that the following four objects are essentially same; * conformally flat n-manifolds (n>=3) with admissible singular points …

In this work we consider the Taylor expansion of the exponential map of a submanifold immersed in R^n up to order three, in order to introduce the concepts of lateral and frontal deviation. We compute the directions of extreme lateral and frontal deviation for surfaces in R^3. Also we compute, by using the Taylor expan…

In this paper we introduce the notion of cofrontal mappings, as the dual objects to frontal mappings, and study their basic local and global properties. Cofrontals are very special mappings and far from generic nor stable except for the case of submersions. It is observed that any smooth mapping can be $C^0$-approximat…

Extends Kummer's theory to singular surfaces for line congruences.

We study a generalization of constant Gauss curvature -1 surfaces in Euclidean 3-space, based on Lorentzian harmonic maps, that we call pseudospherical frontals. We analyze the singularities of these surfaces, dividing them into those of characteristic and non-characteristic type. We give methods for constructing all n…

Develops weak formulation for spacelike flows in pseudo-Euclidean space.

A geometric construction is provided that associates to a given flat front in $\mathbb{H}^3$ a pair of minimal surfaces in $\mathbb{R}^3$ which are related by a Ribaucour transformation. This construction is generalized associating to a given frontal in $\mathbb{H}^3$ , a pair of frontals in $\mathbb{R}^3$ that are env…

We give the complete solution to the local diffeomorphism classification problem of generic singularities which appear in tangent surfaces, in as wider situations as possible. We interpret tangent geodesics as tangent lines whenever a (semi-)Riemannian metric, or, more generally, an affine connection is given in an amb…

Defines axial curvatures for corank 1 singular manifolds in higher dimensions.

A normal field on a spacelike surface in $R^4_1$ is called bi-normal if $K^ν$, the determinant of Weingarten map associated with $ν$, is zero. In this paper we give a relationship between the spacelike pseudo-planar surfaces and spacelike pseudo-umbilical surfaces, then study the bi-normal fields on spacelike ruled sur…

We present a method for synthesizing a frontal, neutral-expression image of a person's face given an input face photograph. This is achieved by learning to generate facial landmarks and textures from features extracted from a facial-recognition network. Unlike previous approaches, our encoding feature vector is largely…

In this paper, we define dual geodesic trihedron(dual Darboux frame) of a spacelike ruled surface. Then, we study Mannheim offsets of spacelike ruled surfaces in dual Lorentzian space by considering the E. Study Mapping. We represent spacelike ruled surfaces by dual Lorentzian unit spherical curves and define Mannheim …

Study spacelike loxodromes on helicoidal surfaces in Lorentzian n-space.

The paper studies mean curvature flow of spacelike-convex submanifolds in pseudo-Euclidean space.

In this paper, we give the characterizations of spacelike B2-slant helix by means of curvatures of the spacelike curve in Minkowski 4-space. Furthermore, we give the integral characterization of the spacelike B2-slant helix.

Three explicit families of spacelike Zoll surface admitting a Killing field are provided. It allows to prove the existence of spacelike Zoll surface not smoothly conformal to a cover of de Sitter space as well as the existence of Lorentzian Möbius strips of non constant curvature all of whose spacelike geodesics are cl…

In this paper, we investigate the parametric version and non-parametric version of rigidity theorem of spacelike translating solitons in pseudo-Euclidean space $\mathbb{R}^{m+n}_{n}$. Firstly, we classify $m$-dimensional complete spacelike translating solitons in $\mathbb{R}^{m+n}_{n}$ by affine technique and classical…

In this paper, we study entire spacelike translating solitons in Minkowski space. By constructing convex spacelike solutions to (1.3) in bounded convex domains, we obtain many entire smooth convex strictly spacelike translating solitons by prescribing boundary data at infinity.

In this paper, using the classifications of timelike and spacelike ruled surfaces, we define and study the Mannheim offsets of spacelike ruled surfaces in Minkowski 3-space. We give the conditions for spacelike offset surfaces to be developable.

Estimates for spacelike hypersurfaces in de Sitter space.

In this paper, we investigate the relations between the pitch, the angle of pitch and drall of parallel ruled surface of a closed spacelike curve with a spacelike binormal in dual Lorentzian space.

Proves inequality for maximal spacelike submanifolds in Minkowski space.

The paper proves the existence of specific spacelike hypersurfaces in Minkowski space.