Assume given a set of facts in PROLOG of the form father(person1,person2) % person1 is the father of person2

Define a predicate brother(X,Y) which holds iff X and Y are brothers.

Define a predicate cousin(X,Y) which holds iff X and Y are cousins.

Define a predicate grandson(X,Y) which holds iff X is a grandson of Y.

Define a predicate descendent(X,Y) which holds iff X is a descendent of Y.

Consider the following family tree: father(a,b).

father(a,c).

father(b,d).

father(b,e).

father(c,f).

Say which answers, and in which order, are generated by your definitions for the queries

?- brother(X,Y).

?- cousin(X,Y).

?- grandson(X,Y).

?- descendent(X,Y).