The intersection of two ringed surfaces

Presents an efficient and robust algorithm to compute the intersection curve of two ringed surfaces, each being the sweep ∪ _uC^u generated by a moving circle. Given two ringed surfaces ∪_uC₁^u and ∪_vC₂^v, we formulate the condition C ₁^u∩C₂^v≠Ø (i.e. that the intersection of the two circles C₁^u and C ₂^v is non-empty) as a bivariate equation λ(u,v)= 0 of relatively low degree. Except for some redundant solutions and degenerate cases, there is a rational map from each solution of λ(u,v)=0 to the intersection point C₁^u∩C₂^v. Thus, it is trivial to construct the intersection curve once we have computed the zero-set of λ(u,v)=0. We also analyze some exceptional cases and consider how to construct the corresponding intersection curves