Real-linear isometries between certain subspaces of continuous functions

In this paper we first consider a real-linear isometry T from a certain subspace A of C ( X ) (endowed with supremum norm) into C ( Y ) where X and Y are compact Hausdorff spaces and give a result concerning the description of T whenever A is a uniform algebra on X . The result is improved for the case where T ( A ) is, in addition, a complex subspace of C ( Y ). We also give a similar description for the case where A is a function space on X and the range of T is a real subspace of C ( Y ) satisfying a ceratin separating property. Next similar results are obtained for real-linear isometries between spaces of Lipschitz functions on compact metric spaces endowed with a certain complete norm.