Partial extensions of jets and the polar distribution on Grassmannians of non-maximal integral elements
Keywords: 14M15; 35A99; 35A30; 57R99; 53B25; 58A05; 58A15; 58A17; 58A20; 58A30; 58A32; 58C99; 58J99; Jet spaces; Exterior differential systems; Geometry of PDEs;