Remarks
The number of coincident points depends on the resolution of the coordinate system, and on the basis pairs used
Generally, all combination of points should be used as basis pairs, resulting in comparing reference frame systems
Using all combinations might introduce redundancy. Let (ai,ak) and (bj,bl) be the basis pairs, and (ar,bu) and (as,bv) both coincide. Then it is likely that the same coincidence set is found if (ar,as) and (bu,bv) are used as basis. Note however that similarity and not exact equality is used