Grid manifolds
S. A. Robertson · Journal of Differential Geometry · 1970
This paper is intended to correlate the work of several authors on Riemannian manifolds on which there are defined systems of parallel fields of tangent planes.The main facts in this area are the reducibility theorem of de Rham [8] and the fibring theorems of Walker [14].In order to make the exposition as simple as possible, we introduce the concepts of local-product and grid.Our principal result includes a 'grid' version of de Rham's theorem.