Intrinsic Flat Stability of Manifolds with Boundary where Volume Converges and Distance is Bounded Below
Brian Allen, Raquel Perales
TL;DR
The paper proves volume-preserving intrinsic flat convergence of a sequence of compact oriented manifolds with boundary under lower metric bounds $g_j\ge g_0$, uniform diameter bounds, and convergence of volumes, along with boundary metric convergence in $L^{\frac{m-1}{2}}$ (and in stronger $L^{\frac{m}{2}}$ cases). It extends the boundary-free VADB framework to manifolds with boundary via a delta-doubling construction and almost-everywhere distance convergence, then embeds the manifolds into a common space to obtain VF convergence to the prescribed limit $(M,g_0)$. The work includes new boundary-extended theorems, revisits the core VADB machinery, and develops a detailed proof strategy that culminates in applications to the intrinsic flat stability of the positive mass theorem for graphs. The results demonstrate that VF convergence, rather than Gromov-Hausdorff convergence, is the natural notion in this boundary-rich setting and provide a robust method for proving PMT stability in graph and related geometries.
Abstract
Given a compact, connected, and oriented manifold with boundary $M$ and a sequence of smooth Riemannian metrics defined on it, $g_j$, we prove volume preserving intrinsic flat convergence of the sequence to the smooth Riemannian metric $g_0$ provided $g_j$ always measures vectors strictly larger than or equal to $g_0$, the diameter of $g_j$ is uniformly bounded, the volume of $g_j$ converges to the volume of $g_0$, and $L^{\frac{m-1}{2}}$ convergence of the metrics restricted to the boundary. Many examples are reviewed which justify and explain the intuition behind these hypotheses. These examples also show that uniform, Lipschitz, and Gromov-Hausdorff convergence are not appropriate in this setting. Our results provide a new rigorous method of proving some special cases of the intrinsic flat stability of the positive mass theorem.
