In this paper, we study the evolving behaviors of the first eigenvalue of Laplace-Beltrami operator under the normalized Ricci flow of model geometries. In every Bianchi class, we estimate the derivative of the eigenvalue. Then we construct monotonic quantities under the Ricci flow and obtain upper and lower bounds for the eigenvalue.
In this paper, we study the evolving behaviors of the first eigenvalue of Laplace-Beltrami operator under the normalized backward Ricci flow, construct various quantities which are monotonic under the backward Ricci flow and get upper and lower bounds. We prove that in cases where the backward Ricci flow converges to a sub-Riemannian geometry after a proper rescaling, the eigenvalue evolves toward zero.
In this paper, we study monotonicity for the first eigenvalue of a class of $(p,q)$-Laplacian. We find the first variation formula for the first eigenvalue of $(p,q)$-Laplacian on a closed Riemannian manifold evolving by the Ricci-harmonic flow and construct various monotic quantities by imposing some conditions on initial manifold.
On closed Riemannian manifolds with Bakry-Émery Ricci curvature bounded from below and bounded gradient of the potential function, we obtain lower bounds for all positive eigenvalues of the Beltrami-Laplacian instead of the drifted Laplacian. The lower bound of the $k$th eigenvalue depends on $k$, Bakry-Émery Ricci curvature lower bound, the gradient bound of the potential function, and the dimension and diameter upper bound of the manifold, but the volume of the manifold is not involved. Especially, these results apply to closed manifolds with Ricci curvature bounded from below.
Considering the almost rigidity of the Obata theorem, we generalize Petersen and Aubry's sphere theorem about eigenvalue pinching without assuming the positivity of Ricci curvature, only assuming $Ric\geq-Kg$ and $diam\leq D$ for some positive constants $K>0$ and $D>0$.
We consider complete Riemannian $3$-manifolds whose Ricci tensors have constant eigenvalues $(λ, λ, 0)$. When $π_1$ is finitely generated, we classify the topology of such manifolds by showing that they have a free fundamental group if non-trivial and that every free group is obtained. We give a description up to isometry, when the metric is locally irreducible or when it is analytic.
Let $λ(t)$ be the first eigenvalue of $-Δ+aR\, (a>0)$ under the backward Ricci flow on locally homogeneous 3-manifolds, where $R$ is the scalar curvature. In the Bianchi case, we get the upper and lower bounds of $λ(t)$. In particular, we show that when the the backward Ricci flow converges to a sub-Riemannian geometry after a proper re-scaling, $λ^{+}(t)$ approaches zero, where $λ^{+}(t)=\max\{λ(t),0\}$.
Let $M$ be an $n$-dimensional closed Riemannian manifold with metric $g$, $dμ=e^{-ϕ(x)}dν$ be the weighted measure and $Δ_{p,ϕ}$ be the weighted $p$-Laplacian. In this article we will investigate monotonicity for the first eigenvalue problem of the weighted $p$-Laplace operator acting on the space of functions along the Ricci-Bourguignon flow on closed Riemannian manifolds. We find the first variation formula for the eigenvalues of the weighted $p$-Laplacian on a closed Riemannian manifold evolving by the Ricci-Bourguignon flow and we obtain various monotonic quantities. At the end we find som…
We establish a lower bound for the real eigenvalues of a Laplace-Beltrami operator with an $L^\infty$-drift term. We make no assumptions that the operator is self-adjoint or that the drift has any additional regularity. In the case where the operator is self-adjoint, this establishes a lower bound on the spectrum without assuming a lower bound for the Bakry-Emery Ricci tensor. Put colloquially, this result states that no matter which way the wind blows, heat will diffuse at a definite rate depending only on the geometry of the underlying space and the maximal wind speed.
Eigenvalue comparison theorems for the Witten-Laplacian and the weighted $p$-Laplacian on complete manifolds with a modified Ricci curvature bounded from below
Faculty of Mathematics and Statistics, Key Laboratory of Applied Mathematics of Hubei Province, Hubei University(湖北大学数学与统计学学院,湖北省应用数学重点实验室);Key Laboratory of Intelligent Sensing System and Security (Hubei University), Ministry of Education(教育部智能感知系统与安全重点实验室(湖北大学))
Eigenvalue Estimates for Schrödinger Operators on Ricci Shrinkers
Instituto de Matemática e Estatística, Universidade Federal Fluminense(弗鲁米嫩塞联邦大学数学与统计研究所);Departamento de Matemática, Universidade Federal de Sergipe(塞尔希培联邦大学数学系);Universidade Federal do Amazonas Instituto de Ciências Exatas(亚马孙联邦大学理学院)
Eigenvalue monotonicity for the Ricci-Hamilton flow, revised version
这是我们的短文[arxiv.math.DG/0403065]的一个修正版本,其中我们讨论了紧致或完备非紧致黎曼流形上Laplacian算子的特征值对Ricci-Hamilton流的单调性。我们证明了当数量曲率有一个非负的下界且Einstein张量不太负时,紧区域上Lapacian算子的特征值是非减的.这一结果对研究Ricci-Hamilton流的爆破模型是有用的。我们注意到,利用我们的思想,D.Kokotov和D.Korotkin [Normalized Ricci Flow on Riemann Surfaces and Determinant of Laplacian,Letters in数学物理,71(3)(2005)241-242]可以给出一个简单的证明,证明任意亏格g的紧致Riemann曲面上光滑度量中Laplace算子的行列式在归一化里奇流下单调增长.结合Hamilton和B.Chow的结果,在正规化里奇流的作用下,光滑度量渐近地趋向于常曲率度量,这导致Osgood-Phillips-Sarnak定理的简单证明,该定理指出在具有固定共形类和固定体积的光滑度量类内,拉普拉斯算子的行列式在常曲率度量上是最大的。人们可以考虑其他几何流和其他椭圆算子的类似问题,如Yamabe流或Kahler-里奇流。