SIGNATURE SetByPredConstr[data1, data2]

--

-- Parameter
SORT data1 data2

IMPORT SetByPred[data1] ONLY set
       SetByPred[data2]  ONLY set
       SetByPred[pair[data1,data2]] ONLY set
       SetByPred[union[data1, data2]] ONLY set
       Pair[data1, data2] ONLY pair
       Union2[data1, data2] ONLY union

-- cartesian product
FUN x : set[data1] ** set[data2] -> set[pair[data1, data2]]
-- x in A and y in B <=> x & y in A x B

-- disjoint union
FUN U : set[data1] ** set[data2] -> set[union[data1, data2]]
-- x in A and y in B <=> data1(x) in A U B and data2(y) in A U B