lecture.pl

% The sum and subset sum functions were taken from
% Borrowed from https://github.com/jdan/code/blob/master/prolog/subset_sum.pl

% Atoms

good.
bad.

% Writing output
% write(...) Does not work in user mode

% Functors
goes(mary, college).
goes(john, school).
goes(jennifer, college).

% Variables
% goes(Who, Where).
% goes(Who, college).

% Tree ancestor
child(t, a, b).
child(t, a, c).

child(t, b, d).
child(t, b, e).

child(t, c, f).
child(t, c, g).

ancestor(T, X, Y) :- child(T, X, Y). 
ancestor(T, X, Y) :- child(T, X, Z), ancestor(T, Z, Y).

% Tree leaf

leaf(T, X) :- child(T, _, X), not(child(T, X, _)).

% Arithmetic

% N is 5 + 1.
% Y is 6*8*9.

% Sum 
% sum(L, N) :- sum of elements in L is equal to N
sum([], 0).
sum([H|T], N) :- sum(T, N1), N is N1 + H.

% Power function
power(_, 0, 1).
power(X, K, Y) :- K_pred is (K - 1), power(X, K_pred, Y_div), Y is Y_div * X.

% Graph cycle

edge(g1, a, b).
edge(g1, b, c).
edge(g1, c, d).
edge(g1, d, a).

edge(g2, a, b).
edge(g2, b, c).
edge(g2, c, d).


connected(G, X, Y) :- edge(G, X, Y).
connected(G, X, Y) :- edge(G, X, Z), connected(G, Z, Y).

cycle(G) :- connected(G, X, X).

% Example of cut operator
fire(charmander).
fire(charizard).

water(squirtle).
water(blastoise).

grass(bulbasaur).
grass(venasaur).

% Cut operator

good_team :- fire(X), grass(Y), water(Z).
% good_team :- fire(X), ! ,grass(Y), water(Z).