Here is a summary of the result, illustrated by means of a digraph picture, where the "no change" element <math>(\operatorname{d}x)(\operatorname{d}y)</math> is drawn as a loop at the point <math>x~y.</math> | Here is a summary of the result, illustrated by means of a digraph picture, where the "no change" element <math>(\operatorname{d}x)(\operatorname{d}y)</math> is drawn as a loop at the point <math>x~y.</math> |