% Define the parent relationship parent(alice, bob). parent(alice, charlie). parent(bob, david). parent(bob, emily). parent(charlie, frank). parent(charlie, grace). % Define the male and female relationships male(bob). male(charlie). male(david). male(frank). female(alice). female(emily). female(grace). % Define the sister relationship sister(X, Y) :- female(X), parent(Z, X), % X and Y have the same parent parent(Z, Y), % Y and X have the same parent X \= Y. % X and Y are different individuals % Query to find sisters ?- sister(X, Y).
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Prolog (Programming in Logic) is a logic programming language associated with artificial intelligence and computational linguistics. It works through facts, rules, and queries, using a form of symbolic reasoning known as backward chaining. Prolog is declarative, meaning you describe what you want instead of how to compute it.
The following is a simple Prolog program that prints a greeting:
:- initialization(main).
main :-
write('Hello, World!').
Facts represent basic assertions about the world.
likes(alice, pizza).
likes(bob, pasta).
Rules define logical relationships using facts.
friends(X, Y) :- likes(X, Z), likes(Y, Z).
Queries are used to find information based on facts and rules.
?- likes(alice, What).
Operator | Description |
---|---|
:- | Rule definition |
, | Logical AND |
; | Logical OR |
= | Unification |
member(X, [X|_]).
member(X, [_|T]) :- member(X, T).
Prolog heavily relies on recursion.
factorial(0, 1).
factorial(N, F) :-
N > 0,
N1 is N - 1,
factorial(N1, F1),
F is N * F1.
This guide provides a quick reference to Prolog programming syntax and features. Start writing Prolog code using OneCompiler’s Prolog online compiler today!