Put in catch-conditions to preclude R2Up moves being performed on 0- and 1-crossing diagrams because the regions method returns incorrect results in these (and only these) cases, in a way that disrupts only the proper functioning of R2Up moves. Note further that the diagram obtained from a 0-crossing or 1-crossing diagram by an R2Up move can also be obtained by a sequence of two R1Up moves, and by a sequence of two R1Up moves followed by an R3 move, respectively.