An arrangement of pseudocircles is a finite collection of Jordan curves in the plane with the additional properties that (i) every two curves meet in at most two points; and (ii) if two curves meet in a point p, then they cross at p. We say that two arrangements C = (c1, . . . , cn) and D = (d1, . . . , dn) are equivalent if there is a homeomorphism φ of the plane onto itself such that φ[ci] = ...