Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userRobust index bounds for minimal hypersurfaces of isoparametric submanifolds and symmetric spaces
78
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We find many examples of compact Riemannian manifolds $(M,g)$ whose closed minimal hypersurfaces satisfy a lower bound on their index that is linear in their first Betti number. Moreover, we show that these bounds remain valid when the metric $g$ is replaced with $g$ in a neighbourhood of $g$. Our examples $(M,g)$ consist of certain minimal isoparametric hypersurfaces of spheres; their focal manifolds; the Lie groups $SU(n)$ for $nleq 17$, and $Sp(n)$ for all $n$; and all quaternionic Grassmannians.
rate research
Read More
An isoparametric hypersurface in unit spheres has two focal submanifolds. Condition A plays a crucial role in the classification theory of isoparametric hypersurfaces in [CCJ07], [Chi16] and [Miy13]. This paper determines $C_A$, the set of points with Condition A in focal submanifolds. It turns out that the points in $C_A$ reach an upper bound of the normal scalar curvature $rho^{bot}$ (sharper than that in DDVV inequality [GT08], [Lu11]). We also determine the sets $C_P$ (points with parallel second fundamental form) and $C_E$ (points with Einstein condition), which achieve two lower bounds of $rho^{bot}$.
For any smooth Riemannian metric on an $(n+1)$-dimensional compact manifold with boundary $(M,partial M)$ where $3leq (n+1)leq 7$, we establish general upper bounds for the Morse index of free boundary minimal hypersurfaces produced by min-max theory in the Almgren-Pitts setting. We apply our Morse index estimates to prove that for almost every (in the $C^infty$ Baire sense) Riemannan metric, the union of all compact, properly embedded free boundary minimal hypersurfaces is dense in $M$. If $partial M$ is further assumed to have a strictly mean convex point, we show the existence of infinitely many compact, properly embedded free boundary minimal hypersurfaces whose boundaries are non-empty. Our results prove a conjecture of Yau for generic metrics in the free boundary setting.
A submanifold in space forms is isoparametric if the normal bundle is flat and principal curvatures along any parallel normal fields are constant. We study the mean curvature flow with initial data an isoparametric submanifold in Euclidean space and sphere. We show that the mean curvature flow preserves the isoparametric condition, develops singularities in finite time, and converges in finite time to a smooth submanifold of lower dimension. We also give a precise description of the collapsing.
For a closed hypersurface $M^nsubset S^{n+1}(1)$ with constant mean curvature and constant non-negative scalar curvature, the present paper shows that if $mathrm{tr}(mathcal{A}^k)$ are constants for $k=3,ldots, n-1$ for shape operator $mathcal{A}$, then $M$ is isoparametric. The result generalizes the theorem of de Almeida and Brito cite{dB90} for $n=3$ to any dimension $n$, strongly supporting Cherns conjecture.
We revisit Allendoerfer-Weils formula for the Euler characteristic of embedded hypersurfaces in constant sectional curvature manifolds, first taking some time to re-prove it while demonstrating techniques of [2] and then applying it to gain new understanding of isoparametric hypersurfaces.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
