arXiv research

Classifies homogeneous hypersurfaces in specific 4D geometries.

Method resolves 4D symplectic orbifolds using complex geometry.

The study classifies 331 specific 4D polytopes with 7 facets.

The paper shows how profinite completions can reveal 4D geometries except for specific cases.

Global regularity proved for 4D Ricci flow with scalar curvature integral bound.

Study on 4D compact Ricci solitons and their geometric properties.

Study steady gradient Ricci solitons with cylindrical tangent flows at infinity.

We find analogues of the Willmore functional for each of the Thurston geometries with 4-dimensional isometry group such that the CMC-spheres in these geometries are critical points of these functionals.

The paper establishes correspondences between quaternionic spinors, Minkowski flags, and hyperbolic horospheres.

This paper confirms volumes of geodesic balls can identify 4D space forms.

We study the asymptotic cones of the universal covering spaces of closed 4-dimensional nonpositively curved real analytic manifolds. We show that the existence of nonstandard components in the Tits boundary, discovered by Christoph Hummel and Victor Schroeder, depends only on the quasi-isometry type of the fundamental …

For spacelike stationary (i.e. zero mean curvature) surfaces in 4-dimensional Lorentz space one can naturally introduce two Gauss maps and Weierstrass representation. In this paper we investigate their global geometry systematically. The total Gaussian curvature is related with the surface topology as well as the indic…

In this paper, we establish equiform differential geometry of space and timelike curves in 4-dimensional Minkowski space. We obtain some conditions for these curves. Also, general helices with respect to their equiform curvatures are characterized.

Using 4-dimensional arithmetic hyperbolic manifolds, we construct some new homological quantum error correcting codes. They are LDPC codes with linear rate and distance $n^ε$. Their rate is evaluated via Euler characteristic arguments and their distance using $\mathbb{Z}_2$-systolic geometry. This construction answers …

Study linear perturbations in Schwarzschild black hole spacetime.

Study 4D steady gradient Ricci solitons reducing to 3D manifolds.

The conformal geometry of spacelike surfaces in 4-dimensional Lorentzian space forms has been studied by the authors in a previous paper, where the so-called polar transform was introduced. Here it is shown that this transform preserves spacelike conformal isothermic surfaces. We relate this new transform with the know…

4-dimensional spaces equipped with 2-dimensional (complex holomorphic or real smooth) completely integrable distributions are considered. The integral manifolds of such distributions are totally null and totally geodesics 2-dimensional surfaces which are called the null strings. Properties of congruences (foliations) o…

Study perturbs Dirac operator on 4D manifolds, proving Kastler-Kalau-Walze theorems.

Spacelike Willmore surfaces in 4-dimensional Lorentzian space forms, a topic in Lorentzian conformal geometry which parallels the theory of Willmore surfaces in $S^4$, are studied in this paper. We define two kinds of transforms for such a surface, which produce the so-called left/right polar surfaces and the adjoint s…

Flat minimal hypersurfaces in 4D space are always flat.

The paper defines marginal tubes and proves their null nature.

We study the spectral geometry of the conformal Jacobi operator on a 4-dimensional Riemannian manifold (M,g). We show that (M,g) is conformally Osserman if and only if (M,g) is self-dual or anti self-dual. Equivalently, this means that the curvature tensor of (M,g) is given by a quaternionic structure, at least pointwi…

In low dimensional topology, we have some invariants defined by using solutions of some nonlinear elliptic operators. The invariants could be understood as Euler class or degree in the ordinary cohomology, in infinite dimensional setting. Instead of looking at the solutions, if we can regard some kind of homotopy class…

Study on 4D Lie groups and related almost hypercomplex manifolds.

Study on rotating surfaces in 4D space with matrices.

Study of symmetries in 4D Lie groups.

We show that if $M$ is an orientable 4-dimensional infrasolvmanifold and either $β=β_1(M;\mathbb{Q})\geq2$ or $M$ is a $\mathbb{S}ol_0^4$- or a $\mathbb{S}ol_{m,n}^4$-manifold (with $m\not=n$) then $M$ is parallelizable. There are non-parallelizable examples with $β=1$ for each of the other solvable Lie geometries $\ma…

New universal invariant operators are introduced in a class of geometries which include the quaternionic structures and their generalisations as well as 4-dimensional conformal (spin) geometries. It is shown that, in a broad sense, all invariants and invariant operators arise from these universal operators and that the…

The paper studies projectively equivalent para-Kaehler metrics in 4D.

New flow connects symplectic maps to hyperKähler geometry.

The purpose of this article is to view Penrose rhombus tilings from the perspective of symplectic geometry. We show that each thick rhombus in such a tiling can be naturally associated to a highly singular 4-dimensional compact symplectic space, while each thin rhombus can be associated to another such space; both spac…

The paper disproves some implications in convex projective geometry.

Classifies all toric Kahler surfaces with twistor 2-forms.

We study 4-dimensional homology cobordisms without 3-handles, showing that they interact nicely with Thurston geometries, character varieties, and instanton and Heegaard Floer homologies. Using these, we derive obstructions to such cobordisms. As one example of these obstructions, we generalize other recent results on …

4D gradient solitons with constant curvature are rigid.

Study on 4D Einstein manifolds with Kähler conformal geometry.

The target space of a (4,0) supersymmetric two-dimensional sigma model with Wess-Zumino term has a connection with totally skew-symmetric torsion and holonomy contained in Sp(n).Sp(1), QKT-connection. We study the geometry of QKT-connections. We find conditions to the existence of a QKT-connection and prove that if it …

Survey of recent progress in gravitational instantons

Study 4D solitons with specific curvature properties, proving curvature bounds and classifying solutions.

We show that symplectic forms taming complex structures on compact manifolds are related to special types of almost generalized Kähler structures. By considering the commutator $Q$ of the two associated almost complex structures $J_{\pm}$, we prove that if either the manifold is 4-dimensional or the distribution ${Im} …

We find G2-manifolds with specific asymptotic properties.

Defines and proves generalized noncommutative residue theorems for specific dimensions.

A smooth five-dimensional s-cobordism becomes a smooth product if stabilized by a finite number n of $S^2xS^2x[0,1]$'s. We show that for amenable fundamental groups, the minimal n is subextensive in covers, i.e., n(cover)/index(cover) has limit 0. We focus on the notion of sweepout width, which is a bridge between 4-di…

Any oriented 4-dimensional real vector bundle is naturally a line bundle over a bundle of quaternion algebras. In this paper we give an account of modules over bundles of quaternion algebras, discussing Morita equivalence, characteristic classes and K-theory. The results have been used to describe obstructions for the …

Proof outlined for 4D smooth Poincaré conjecture.

Study non-Weinstein Liouville geometry via hyperbolic dynamics, proving rigidity results.

Modeling curvature-sensitive cells in visual cortex using manifold geometry.