title: General covariance and harmonic maps.
abstract: The principle of general covariance is used to derive the conditions for a map to be harmonic. Modification to the harmonic map equations due to the presence of a Yang-Mills field is described.
authors.affiliation: Department of Mathematics, Harvard University, Cambridge, MA 02138, USA.
authors.forename: S
authors.initials: S
authors.lastname: Sternberg