GEOMETRICAL AND ANALYTICAL PROPERTIES OF CHEBYSHEV SETS IN RIEMANNIAN MANIFOLDS.

We discuss Chebyshev sets of Riemannian manifolds. These are closed sets characterized by the existence of a well-defined distance-realizing projection onto them. The results we establish relate analytical properties of the distance function to these sets to their geometrical properties. They are extensions of some theorems on Chebyshev sets in Euclidean space to the context of Riemannian manifolds. [ABSTRACT FROM AUTHOR]