If R1 and R2 are two union compatible relations or functions, then the result of R3 = R1 ∩R2 is the relation that contains all tuples that are in both the relations In other words, R3will have tuples such that R3 = {t | R1 ∋ t ∧ R2 ∋ t}.

Example:

 R1

  R2                     

R3 = R1 ∩ R2 is

Note: 1) Intersection is an associative operation, i.e., R1 ∩ (R2 ∩ R3) = (R1 ∩ R2) ∩ R3

2) Intersection is a commutative operation, i.e., R1 ∩ R2 = R2 ∩ R1