We give a sharp extrinsic lower bound for the first eigenvalues of the intrinsic Dirac operator of certain hypersurfaces bounding a compact domain in a spin manifold of negative scalar curvature. Limiting-cases are characterized by the existence, on the domain, of imaginary Killing spinors. Some geometrical applications, as an Alexandrov type theorem, are… (More)
— Using the idea of approach space due to Robert Lowen [Approach spaces. The missing link in the topology-uniformity-metric triad], we define the notion of fuzzy approach spaces as a natural generalization of fuzzy metric spaces due to Kramosil and Michalek [Kybernetika , 11, 1975, 336–344] and prove some properties of fuzzy approach spaces.