2016/06/06 by Pro, Curtis, Wilhelm, Frederick
#53C20 #Differential Geometry (math.DG) #FOS: Mathematics
paper · doi:10.48550/arxiv.1606.01828
Given k∈ ℝ, v, D>0, and n∈ ℕ, let \ Mα\ α=1∞ be a Gromov-Hausdorff convergent sequence of Riemannian n--manifolds with sectional curvature ≥ k, volume >v, and diameter ≤ D. Perelman's Stability Theorem implies that all but finitely many of the Mαs are homeomorphic. The Diffeomorphism Stability Question asks whether all but finitely many of the Mαs are diffeomorphic. We answer this question affirmatively in the special case when all of the singularities of the limit space occur along smoothly and isometrically embedded Riemannian manifolds of codimension ≤ 3. We then describe several applications. For instance, if the limit space is an orbit space whose singular strata are of codimension at ≤ 3, then all but finitely many of the Mαs are diffeomorphic.