Fig. 4: Turning a specific edge/corner block to the desired position.

a Replacing an edge block in the fluid path. The algorithm for this change: M′D′MS′. b Replacing a corner block in the fluid path. The algorithm for this change: RDR′. The bottom illustrations represent the twisting procedure, where we wish to substitute the red block with the green block while keeping the blue blocks unchanged. Explanations of the notations can be found in ref. 26