set: {3,1,4,5} = {1,3,4,5}			orderless, 	no duplicates			very common in computing


multiset: {2,2,2,3,3}				orderless, 	duplicates matter		rare in computing


sequence: (3,1,4,1,5) ≠ (1,3,4,5)	ordered, 		duplicates matter		common in computing


Cartesian Product
	A × B = { (a,b) | a ∈ A  ∧  b ∈ B }
	A × B × C = { (a,b,c) | a ∈ A  ∧  b ∈ B  ∧ c ∈ C }
	A³ = A × A × A = { (x,y,z) | x ∈ A  ∧  y ∈ A  ∧ z ∈ A }

{0,1}³ = set of all sequences of 3 0s and 1s {"000", "001", "010", ..., "111"}