ABSTRACT

There exist different types of singularities. Assume that M = (xo, yo) is a singularity of y and some second derivatives of the function p do not vanish at M. Let us introduce some notations:

There are three cases with respect to D:

(a) if D > 0, then M is called an isolated point of y (Figure 9. la); (h) if D < 0, then M is called a point of self-intersection of y (Figure 9.lb); (c) if D = 0, then M is either an isolatedpoint, or a cusp, which can be of two types,

or an osculate point of y (Figure 9. lc).