inter is:exact

Some general transformation where the arguments that are not present are calculated from the one data argument a being just present. Can be used to contstruct function a -> d from some additional ideas.
inter c0 c1 is a list of all possible points of intersection between curves c0 and c1 : if (u,v,w,x) is returned by inter, then curve c0 may intersect with c1 between parameter values u and v, which corresponds to parameter values between w and x for c1. The implementation guarantees that all actual solutions are found, but possibly false solutions may also be returned.