Survey updates knowledge on homogeneous Einstein spaces.
problem Understanding homogeneous Einstein spaces.
method Building on previous surveys by Wang and Lauret.
result Current state of homogeneous Einstein spaces.
New formula for Lichnerowicz Laplacian on homogeneous spaces.
problem Finding new Einstein metrics on homogeneous spaces.
method Using Casimir operators to derive a new formula for the Lichnerowicz Laplacian.
result Derives many new Einstein metrics stable in the Einstein-Hilbert sense.
We show that homogeneous Einstein metrics on Euclidean spaces are Einstein solvmanifolds, using that they admit periodic, integrally minimal foliations by homogeneous hypersurfaces. For the geometric flow induced by the orbit-Einstein condition, we construct a Lyapunov function based on curvature estimates which come f…
In this article, we study Einstein Kropina metrics on Lie groups and homogeneous spaces. We give a method to construct Einstein Kropina metrics on Lie groups. As an example of this method, a family of non-Riemannian Einstein Kropina metrics on the special orthogonal group SO(n) is given. Then, we classify all left in…
Study on stability of non-diagonal Einstein metrics on specific homogeneous spaces.
problem Stability analysis of non-diagonal Einstein metrics on HimesH/ΔK. method Formula for scalar curvature, study of stability with Hilbert action.
result Non-diagonal Einstein metrics on M are unstable with different coindexes. Einstein metrics on homogeneous torus bundles
problem Einstein metrics on total space of homogeneous torus bundles
method Descend to common base and establish estimates
result Prove precompactness theorem for Einstein manifolds
New proof shows no negative curvature Einstein metrics in specific dimensions.
problem Proving nonexistence of certain Einstein metrics in 9 and 10 dimensions.
method Cohomogeneity-one approach to show nonexistence of negative curvature Einstein metrics.
result Noncompact homogeneous spaces not diffeomorphic to Euclidean space of dimension 9 or 10 admit no homogeneous Einstein metrics of negative Ricci curvature, with only three potential exceptions.
Study the stability of Einstein metrics on homogeneous spaces.
problem Classify Einstein metrics on homogeneous spaces.
method Analyze the scalar curvature functional to understand stability.
result Identify the nature of each Einstein metric as a critical point.
Study stability of Einstein metrics on homogeneous spaces.
problem Stability of Einstein metrics on homogeneous spaces.
method Formula for Lichnerowicz Laplacian of G-invariant TT-tensors to study stability.
result Detailed study of naturally reductive Einstein metrics.
Graev's nerve implies invariant Einstein metrics on homogeneous spaces.
problem Existence of invariant Einstein metrics on homogeneous spaces.
method Lie-theoretic definition of Graev's nerve and curvature estimates.
result Detailed description of Graev's work and curvature estimates.
The paper studies Einstein metrics on homogeneous supermanifolds.
problem The finiteness conjecture from classical homogeneous geometry fails on supermanifolds.
method Explicit curvature formulas and construction of homogeneous supermanifolds using Dynkin diagrams.
result Examples of compact homogeneous supermanifolds with no solutions, discrete and continuous families of solutions.
The paper studies stability of Einstein metrics on non-simple Lie group homogeneous spaces.
problem Classifying compact homogeneous spaces with standard Einstein metrics.
method Analysis of scalar curvature functional and coindex.
result Most standard Einstein metrics on non-simple Lie group homogeneous spaces are unstable.
Study Einstein metrics on aligned homogeneous spaces with maximal third Betti number.
problem Existence and classification of Einstein metrics on specific homogeneous spaces.
method Analysis of isotropy representation and computation of Ricci curvature.
result Computation of Ricci curvature formulas for aligned homogeneous spaces.
Study on stability of minimal submanifolds in specific Einstein manifolds.
problem Investigating stability of minimal submanifolds in Einstein manifolds.
method Analyzing homogeneous minimal hypersurfaces in Page space and Sasaki-Einstein manifolds, computing stability operators and indices.
result Determined all homogeneous, minimal hypersurfaces and computed their stability operators and indices.
In this paper we consider connections between Ricci solitons and Einstein metrics on homogeneous spaces. We show that a semi-algebraic Ricci soliton admits an Einstein one-dimensional extension if the soliton derivation can be chosen to be normal. Using our previous work on warped product Einstein metrics, we show that…
Study on Einstein metrics on specific homogeneous spaces.
problem Existence of invariant Einstein metrics on aligned homogeneous spaces.
method Analysis of G_1xG_2-invariant Einstein metrics on G_1/K x G_2/K for compact Lie groups.
result Existence of Einstein metrics is equivalent to a real root of a quartic polynomial.
It is an important problem in differential geometry to find non-naturally reductive homogeneous Einstein metrics on homogeneous manifolds. In this paper, we consider this problem for some coset spaces of compact simple Lie groups. A new method to construct invariant non-naturally reductive Einstein metrics on normal ho…
In this work we study the existence of homogeneous Einstein metrics on the total space of homogeneous fibrations such that the fibers are totally geodesic manifolds. We obtain the Ricci curvature of an invariant metric with totally geodesic fibers and some necessary conditions for such a metric to be Einstein in terms …
We give an overview of progress on homogeneous Einstein metrics on large classes of homogeneous manifolds, such as generalized flag manifolds and Stiefel manifolds. The main difference between these two classes of homogeneous spaces is that their isotropy representation does not contain/contain equivalent summands. We …
Upper bounds on Einstein metrics on homogeneous spaces.
problem Counting isolated homogeneous Einstein metrics on compact spaces.
method Combinatorial volume computation of polytopes, algebraic statistics, numerical algebraic geometry.
result Explicit upper bounds confirmed for Einstein metrics on specific spaces.
Study Einstein metrics on HimesH/ΔK spaces.
problem Existence and classification of invariant Einstein metrics on HimesH/ΔK. method Investigate HimesH-invariant Einstein metrics on M=HimesH/ΔK. result Find unstable Einstein metrics on M for many spaces H/K. The study examines conical Kähler-Einstein metrics on specific Fano manifolds and their behavior at the limit angle.
problem Analyzing conical Kähler-Einstein metrics on rank one horosymmetric Fano manifolds.
method Investigates the convergence of these metrics as the cone angle approaches zero, focusing on the behavior on the complement of a codimension one orbit.
result The metrics converge to the Kähler-Einstein metric on the basis and Stenzel's Ricci flat Kähler metrics on the fibers.
Formula for Lichnerowicz Laplacian on invariant metrics, deducing stability of Einstein manifolds.
problem Stability of Einstein manifolds in homogeneous spaces.
method Formula for Lichnerowicz Laplacian, computation of spectra, analysis of scalar curvature.
result Deduction of G-stability and critical point types of Einstein metrics. We examine the space of solutions to the affine quasi--Einstein equation in the context of homogeneous surfaces. As these spaces can be used to create gradient Yamabe solitions, conformally Einstein metrics, and warped product Einstein manifolds using the modified Riemannian extension, we provide very explicit descript…
A Riemannian manifold (M,ρ) is called Einstein if the metric ρ satisfies the condition $\Ric (ρ)=c\cdot ρ$ for some constant c. This paper is devoted to the investigation of G-invariant Einstein metrics with additional symmetries, on some homogeneous spaces G/H of classical groups. As a consequence, we obtain…
Let G be a simple compact connected Lie group. We study homogeneous Einstein metrics for a class of compact homogeneous spaces, namely generalized flag manifolds G/H with second Betti number b2(G/H)=1. There are 8 infinite families G/H corresponding to a classical simple Lie group G and 25 exceptional flag…
Study finds homogeneous spaces with geodesic orbits but no integrable distributions.
problem Characterizing homogeneous spaces with specific geometric properties.
method Examined Lie groups with compact stabilizers and classified spaces based on geodesic orbits and integrable distributions.
result Identified homogeneous spaces with geodesic orbits but lacking integrable invariant distributions.
Existence and convergence of ancient Ricci flow solutions on compact homogeneous spaces.
problem Existence and characterization of ancient solutions to the Ricci flow on compact homogeneous spaces.
method General existence theorem and Gromov-Hausdorff convergence under rescaling.
result Convergence of collapsed ancient solutions to Einstein metrics on torus fibrations.
Study rigidifies Einstein manifolds with symmetry, proving conjecture.
problem Einstein manifolds with negative scalar curvature and Lie group action.
method Rigidity result for nilradical action and minimal Einstein submanifolds.
result Alekseevskii conjecture proven for negative scalar curvature homogeneous manifolds.
In this paper, we consider half-flat SU(3)-structures and the subclasses of coupled and double structures. In the general case we show that the intrinsic torsion form w1− is constant in each of the two subclasses. We then consider the problem of finding half-flat structures inducing Einstein metrics on homogeneou…
Study proves structure results for homogeneous spaces supporting specific equations.
problem Proving structure results for homogeneous spaces supporting specific equations.
method Analyzing homogeneous spaces with non-constant solutions to two general classes of equations involving the Hessian and an invariant 2-tensor.
result Generalizes rigidity results for gradient Ricci solitons and warped product Einstein metrics.
Researchers find solutions to Einstein equations in higher dimensions.
problem Finding spatially homogeneous solutions to vacuum Einstein equations in general dimensions.
method Assumed spatially homogeneous spacetime, solved Einstein equations for globally hyperbolic spacetimes with specific symmetry groups.
result Spatially homogeneous solutions found, corresponding to Bianchi type II in 4D, and constraints on spacetime expansion.
We construct new homogeneous Einstein spaces with negative Ricci curvature in two ways: First, we give a method for classifying and constructing a class of rank one Einstein solvmanifolds whose derived algebras are two-step nilpotent. As an application, we describe an explicit continuous family of ten-dimensional Einst…
Study homogeneous Einstein metrics on specific non-Kähler C-spaces.
problem Classify and analyze homogeneous Einstein metrics on non-Kähler C-spaces.
method Use painted Dynkin diagrams and mapping degree theory to classify and find Einstein metrics.
result Existence and classification of invariant Einstein metrics on specific spaces.
A method, due to Élie Cartan, is used to give an algebraic classification of the non-reductive homogeneous pseudo-Riemannian manifolds of dimension four. Only one case with Lorentz signature can be Einstein without having constant curvature, and two cases with (2,2) signature are Einstein of which one is Ricci-flat. If…
We classify non-reductive four-dimensional homogeneous conformally Einstein manifolds.
Local Sasaki-Ricci solitons are η-Einstein in certain fiber products of homogeneous Sasakian manifolds.
problem Characterizing local immersions of Sasaki-Ricci solitons into homogeneous Sasakian manifolds.
method Analyzing local Sasakian immersions of Sasaki-Ricci solitons into fiber products of homogeneous Sasakian manifolds.
result Sasaki-Ricci solitons are η-Einstein in certain fiber products of homogeneous Sasakian manifolds. In this article we study homogeneous warped product Einstein metrics and its connections with homogeneous Ricci solitons. We show that homogeneous (λ,n+m)-Einstein manifolds (which are the bases of homogeneous warped product Einstein metrics) are one-dimensional extensions of algebraic solitons. This answers a questi…
Unique domain found in Einstein universe, simplifying manifold classification.
problem Classifying closed conformally flat manifolds with proper development.
method Identifying and analyzing almost-homogeneous domains in the Einstein universe.
result Found a unique domain (diamond) in the Einstein universe that simplifies manifold classification.
We classify noncompact homogeneous spaces which are Einstein and asymptotically harmonic. This completes the classification of Riemannian harmonic spaces in the homogeneous case: Any simply connected homogeneous harmonic space is flat, or rank-one symmetric, or a nonsymmetric Damek-Ricci space. Independently, Y. Nikola…
The Ricci flow is a parabolic evolution equation in the space of Riemannian metrics of a smooth manifold. To some extent, Einstein equations give rise to a similar hyperbolic evolution. The present text is an introductory exposition to Bianchi-Ricci and Bianchi-Einstein flows, that is, the restricted finitely dimension…
In this paper, we study the solvmanifolds constructed from any parabolic subalgebras of any semisimple Lie algebras. These solvmanifolds are naturally homogeneous submanifolds of symmetric spaces of noncompact type. We show that the Ricci curvatures of our solvmanifolds coincide with the restrictions of the Ricci curva…
Compact quasi-Einstein metrics with constant scalar curvature are locally homogeneous in 3D.
problem Characterize compact quasi-Einstein metrics with constant scalar curvature.
method Connection to Sasakian geometry and circle bundles over Einstein metrics.
result Compact quasi-Einstein metrics with constant scalar curvature are locally homogeneous in 3D.
Researchers prove spectral uniqueness of complex/quaternionic structures on manifolds.
problem Spectral uniqueness of complex/quaternionic structures on manifolds.
method Explicit expression for smallest positive eigenvalue of Laplace-Beltrami operator.
result Irreducible symmetric spaces are spectrally unique within families of homogeneous metrics.
The paper proves rigidity theorems on holomorphic isometries into homogeneous domains.
problem Characterizing and comparing holomorphic isometries into homogeneous bounded domains.
method Two rigidity theorems on holomorphic isometries into homogeneous bounded domains.
result The flat (definite or indefinite) complex Euclidean space is not a relative of a homogeneous bounded domain.
Given a non compact semisimple Lie group G we describe all homogeneous spaces G/L carrying an invariant almost Kähler structure (ω,J). When L is abelian and G is of classical type, we classify all such spaces which are Chern-Einstein, i.e. which satisfy ρ=λω for some λ∈R, where ρ is the Ricci…
The paper proves stability of a Ricci flat metric on a product of Einstein homogeneous spaces.
problem Stability of Bismut Ricci flat metrics on product spaces.
method Generalized Ricci flow on aligned homogeneous spaces.
result The Bismut Ricci flat metric is asymptotically and globally stable under the generalized Ricci flow.
The paper studies Einstein metrics on specific manifolds and their rigidity properties.
problem Investigating rigidity of Einstein metrics on homogeneous Gray manifolds.
method Computing coindex and analyzing infinitesimal deformations of Einstein metrics.
result Infinitesimal Einstein deformations on F1,2=SU(3)/T2 are not integrable.