Differential Geometry and its Applications最新文献

Previously we finish the establishment of the transversality of the general part of the Vafa-Witten moduli spaces, in this paper, we deal with the rest, i.e., the reduced part. We consider Vafa-Witten equation on closed, oriented and smooth Riemann 4-manifolds with $C\equiv 0$, and construct perturbation to establish the transversality of the perturbed equation. We show that for a generic choice of the perturbation terms, the moduli space of solutions to the perturbed reduced Vafa-Witten equation for the structure group $SU\left(2\right)$ or $SO\left(3\right)$ on a closed 4-manifold is a smooth manifold of dimension zero. Finally we prove that for two generic orientation-preserving parameters, the corresponding moduli spaces are cobordant, and the method can also be applied to the general part.

Let $P:=U(p+q)/U\left(p\right)\times U\left(q\right)$ be the complex Grassmann manifold and $F:T^{1,0}P\to [0,+\infty )$ be an arbitrary $U(p+q)$-invariant strongly pseudoconvex complex Finsler metric. We prove that F is necessary a Kähler-Berwald metric which is not necessary Hermitian quadratic. We also prove that F is Hermitian quadratic if and only if F is a constant multiple of the canonical $U(p+q)$-invariant Kähler metric on $P$. In particular on the complex projective space ${\mathrm{CP}}^n=U(n+1)/U\left(n\right)\times U\left(1\right)$, there exists no $U(n+1)$-invariant strongly pseudoconvex complex Finsler metric other than a constant multiple of the Fubini-Study metric. These invariant metrics are of particular interesting since they are the most important examples of strongly pseudoconvex complex Finsler metrics on $P$ which are elliptic metrics in the sense that they enjoy very similar holomorphic sectional curvature and bisectional curvature properties as that of the $U(p+q)$-invariant Kähler metrics on $P$, nevertheless, these invariant metrics are not necessary Hermitian quadratic, hence provide nontrivial explicit examples for complex Finsler geometry in the compact cases.

This study is focused on the investigation of lightlike hypersurfaces of a generalized Robertson-Walker (GRW) spacetime. Recently, Poyraz (2022) [51], [52] established some basic inequalities involving various curvature invariants of screen homothetic lightlike hypersurfaces of GRW spacetimes, like k-scalar curvature and k-Ricci curvature. In this work, we consider other basic curvature invariants, namely the scalar curvature and δ-Casorati curvatures, and derive new inequalities for such hypersurfaces of a GRW spacetime. We also find the conditions for which the equality cases in these inequalities hold and give some applications in Lorentzian geometry.

In this paper, we find a new tensor which is responsible for Finsler metrics with reversible geodesics. Using this tensor, we can prove that Finsler metrics are Douglas metrics if and only if they have reversible geodesics and Douglas curvature. Further, we focus on Finsler metrics with reversible Douglas curvature.

We study the Gromov–Hausdorff convergence of metric pairs and metric tuples and prove the equivalence of different natural definitions of this concept. We also prove embedding, completeness and compactness theorems in this setting. Finally, we get a relative version of Fukaya's theorem about quotient spaces under Gromov–Hausdorff equivariant convergence and a version of Grove–Petersen–Wu's finiteness theorem for stratified spaces.

We study geometric structures arising from Hermitian forms on linear spaces over real algebras beyond the division ones. Our focus is on the dual numbers, the split-complex numbers, and the split-quaternions. The corresponding geometric structures are employed to describe the spaces of oriented geodesics in the hyperbolic plane, the Euclidean plane, and the round 2-sphere. We also introduce a simple and natural geometric transition between these spaces. Finally, we present a projective model for the hyperbolic bidisc, that is, the Riemannian product of two hyperbolic discs.

In this paper, we achieve a Reilly type integral formula associated with the ϕ-Laplacian. As its applications, we obtain Heintze-Karcher and Minkowski type inequalities. Furthermore, almost Schur lemmas are also given. They recover the partial results of Li and Xia in [17]. On the other hand, we also study eigenvalue problem for Wentzell boundary conditions and obtain eigenvalue relationships.

We study sequences of immersions respecting bounds coming from Riemannian geometry and apply the ensuing results to the study of sequences of submanifolds of symplectic and contact manifolds. This allows us to study the subtle interaction between the Hausdorff metric and the Lagrangian Hofer and spectral metrics. In the process, we get proofs of metric versions of the nearby Lagrangian conjecture and of the Viterbo conjecture on the spectral norm. We also get $C^0$-rigidity results for a vast class of important submanifolds of symplectic and contact manifolds in the presence of Riemannian bounds. Likewise, we get a Lagrangian generalization of results of Hofer [19] and Viterbo [42] on simultaneous $C^0$ and Hofer/spectral limits — even without any such bounds.

We characterize the vanishing of the shifted Courant-Nijenhuis torsion as the strongest tensorial integrability condition that can be imposed on a skew-symmetric endomorphism of the generalized tangent bundle.

In this paper, we define and characterize 3-Sasakian statistical manifolds and then investigate statistical submersions from 3-Sasakian statistical manifolds. We prove that invariant statistical submersions from 3-Sasakian statistical manifolds with vertical structure vector fields have 3-Sasakian statistical totally geodesic fibers. Moreover, the base space admits a quaternionic Kähler statistical structure. We construct non-trivial examples to illustrate some results of the paper.