English

Diameter Controls and Smooth Convergence away from Singular Sets

Differential Geometry 2018-07-24 v2

Abstract

We prove that if a family of metrics, gig_i, on a compact Riemannian manifold, MnM^n, have a uniform lower Ricci curvature bound and converge to gg_\infty smoothly away from a singular set, SS, with Hausdorff measure, Hn1(S)=0H^{n-1}(S) = 0, and if there exists connected precompact exhaustion, WjW_j, of MnSM^n \setminus S satisfying \diamgi(Mn)D0\diam_{g_i}(M^n) \le D_0 , \volgi(Wj)A0\vol_{g_i}(\partial W_j) \le A_0 and \volgi(MnWj)VjwherelimjVj=0\vol_{g_i}(M^n \setminus W_j) \le V_j where \lim_{j\to\infty}V_j=0 then the Gromov-Hausdorff limit exists and agrees with the metric completion of (MnS,g)(M^n \setminus S, g_\infty). Recall that in the prior work with Sormani the same conclusion is reached but the singular set is assumed to be a submanifold of codimension two. We have a second main theorem in which the Hausdorff measure condition on SS is replaced by diameter estimates on the connected components of the boundary of the exhaustion, Wj\partial W_j. In addition, we show that the uniform lower Ricci curvature bounds in these theorems can be replaced by the existence of a uniform linear contractibility function. If this condition is removed altogether, then we prove that limjdF(Mj,N)=0\lim_{j\to \infty} d_{\mathcal{F}}(M_j', N')=0, in which MjM_j' and NN' are the settled completions of (M,gj)(M, g_j) and (MS,g)(M_\infty\setminus S, g_\infty) respectively and dFd_{\mathcal{F}} is the Sormani-Wenger Intrinsic Flat distance. We present examples demonstrating the necessity of many of the hypotheses in our theorems.

Keywords

Cite

@article{arxiv.1210.0957,
  title  = {Diameter Controls and Smooth Convergence away from Singular Sets},
  author = {Sajjad Lakzian},
  journal= {arXiv preprint arXiv:1210.0957},
  year   = {2018}
}

Comments

36 pages, 1 Figure; revised: Application section added

R2 v1 2026-06-21T22:15:05.062Z