Section 1.3 Ordered Structures
Tuples: Have order and can have repetitions. For example, (6, 7, 6) is a 3-tuple and ( ) is
the empty tuple. We write (x1, , xn) = (y1, , yn) to mean xi = yi for 1 i n.
Cartesian Product: A B = cfw_(x, y) | x A and y B. The