Final answer:
The symmetricDifference predicate in SWI-Prolog calculates the symmetric difference of two sets provided as lists. It uses the built-in subtract predicate to remove common elements and then appends the resultant lists to get the final set.
Step-by-step explanation:
The symmetric difference of two sets A and B is the set of elements that are in either of the sets and not in their intersection. In Prolog, we can define a predicate symmetricDifference/3 that computes this for two lists representing the sets. Below is one way to write the symmetricDifference predicate in SWI-Prolog.
symmetricDifference(A, B, C) :-
subtract(A, B, AB),
subtract(B, A, BA),
append(AB, BA, C).
The predicate subtract is a built-in SWI-Prolog predicate which subtracts the second list from the first. append is another built-in predicate used to concatenate lists. Here, AB would be the elements in A but not in B, and BA vice versa. The resulting lists AB and BA are then concatenated to form the symmetric difference, C.