pricediscount CUST Y pricediscount CUST Z Y Z f a X g Y b p X Y o test relation f a b 3 mary female a b p X foo bar john believes p X q X some constant d some constant d unequal x person some constant d some function arg1 arg2 arg3 some other function arg4 arg5 arg6 friend t b x y Steph o unequal