Answer:
Unification may be a process by which two logical individual atomic expressions, identical by replacing with a correct substitution. within the unification process, two literals are taken as input and made identical using the substitution process. There are some rules of substitution that has got to be kept in mind:
The predicate symbol must be an equivalent for substitution to require place.
The number of arguments that are present in both expressions must be equivalent.
Two similar variables can't be present within the same expression
Explanation:
a. American (Bob), American (y):-
In this scenario, Unification is feasible consistent with the principle. The substitution list is going to be [y/Bob].
b. Enemy (Nono, America), Enemy(x,y):-
In this scenario, the Unification is feasible consistent with the principles. The substitution list is going to be [x/Nono, y/America].
c. Weapon (Missile), soldTo (Missile, y), Weapon (x), soldTo (x, Nono):-
In this scenario, the Unification isn't possible because the predicate is different i.e. Weapon and soldTo.
d. L(x, y), (L(y, x) ^ L(A, B)):-
In this scenario, Unification isn't possible because the number of arguments is different within the given expression