Respuesta :
AXB= {(4,1),(4,5),(4,7),(8,1),(8,5),(8,7),(12,1),(12,5),(12,7)}
BXA = {(1,4),(1,8),(1,12),(5,4),(5,8),(5,12),(7,4),(7,8),(7,12)}
AXA = {(4,4),(4,8),(4,12),(8,4),(8,8),(8,12),(12,4),(12,8)(12,12)}
BXB={(1,1),(1,5),(1,7),(5,1),(5,5),(5,7),(7,1),(7,5),(7,7)}
BXA = {(1,4),(1,8),(1,12),(5,4),(5,8),(5,12),(7,4),(7,8),(7,12)}
AXA = {(4,4),(4,8),(4,12),(8,4),(8,8),(8,12),(12,4),(12,8)(12,12)}
BXB={(1,1),(1,5),(1,7),(5,1),(5,5),(5,7),(7,1),(7,5),(7,7)}