ABSTRACT
If the Maxwell convention is operating, then it is the Ul axis, the conflict set, which is of most interest and jumps wi 11 take place as the trajectory crosses that axis.
Thi sis an appropri ate point to introduce sone useful terminology of Zeeman's (1977-A) in relation to control variables. For this cusp case, he calls Ul the 'splitting factor' and U2 the 'normal factor'. This is because it is the value of Ul which determines whether a trajectory is in a region where the surface is folded. Wi th the coordinates chosen here, if Ul > 0, then the surface is single valued, but it is two-valued within the region for whi ch Uj < O. In the case of the normal factor, U2' x changes monotonically as U2 changes, and continuously except for jumps at the bifurcation points. 1.3.6 The remaining elementary and higher
order catastrophes The seven elementary catastrophes are listed in Table 1.1.
