 Z = 0, then we have the two-form
It also has been seen that formula_31, and so the two-form becomes
This is degenerate as a two-form if, and only if, there exists non-zero "X" for which it is zero for all "Y".Since "h" is non-degenerate it must be that formula_47 and formula_48.So the singularity is degenerate if, and only if, the ambient point "x" lies on the affine normal line to "p" and the reciprocal of its distance from "p" is an eigenvalue of "S", i.e.