theorem :: MCART_1:93

for x1, x2, x3, x4, y1, y2, y3, y4 being object st [[x1,x2],[x3,x4]] = [[y1,y2],[y3,y4]] holds
( x1 = y1 & x2 = y2 & x3 = y3 & x4 = y4 )