New Perspectives on Computer Concepts 2013: Comprehensive 15th Edition by June Jamrich Parsons,Dan Oja

Exercise 35

While browsing through several programs posted online, you come across the following code and realize it is written using the programming language.
male(frodo).
male(mungo).
male(largo).
male(balbo).
female(berylla).
female(belladonna).
female(primula).
female(sella).
parents(mungo,berylla,balbo).
parents(frodo,primula,drogo).
parents(largo,berylla,balbo).
parents(sella,berylla,balbo).
brother_of(X,Y):-
male(Y),
parents(X,Mother,Father),
parents(Y,Mother,Father).