%%%% File: Music World

%% Facts...

% chopin(N, piece(L), year(M)) :: N is the name of the composer, L is the type of piece, and M is
% year that is was created.


piece(chopin,type(etude), number(2), key(c)).
piece(chopin,type(etude),number(3), key(a)).
piece(chopin,type(scherzo),number(3), key(g)).
piece(chopin,type(sonata),number(1), key(bfl)).
piece(chopin,type(prelude),number(4), key(gfl)).
piece(liszt,type(concerto),number(2), key(a)).
piece(liszt,type(sonata), number(1), key(f)).

% notes(N, beats(L), key(M)) :: N is the name of the note, L is the number of beats, and M is the
% name of the key.
note(quarter, beat(1), pitch(a)).
note(whole, beat(4), pitch(b)).
note(half, beat(2), pitch(c)).
note(quarter, beat(1), pitch(d)).
note(whole, beat(4), pitch(e)).
note(half, beat(2), pitch(f)).
note(half, beat(2), pitch(g)).


%% Rules . . .
% pieces :: all those items listed are types of pieces.
pieces :- piece(_,type(Name),_,_),write(Name),nl,fail.
pieces.

% composers :: all those items listed are the composers in the KB.
composers :- piece(Composer,_,_,_),write(Composer),nl,fail.
composers. 

% Notes :: all those items listed are notes
note :- note(_, _, pitch(Name)), write(Name),nl,fail.
note.

%%Quarter notes :: The specific pitch printed is a quarter note.
quarter(Name) :- note(quarter,_, pitch(Name)),write(Name),nl,fail.

%%Half notes :: The specific pitch printed is a half note.
half(Name) :- note(half,_, pitch(Name)),write(Name),nl,fail.

%%Whole notes :: The specific pitch printed is a whole note.
whole(Name) :- note(whole,_, pitch(Name)),write(Name),nl,fail.

%beats(Name, A) :: A is the number of beats of the specified note which is Name.
beats(Name, A) :- note(Name, beat(B), _), A is B.

%beats_of_pitch(Name, A) :: A is the number of beats of the specified pitch.
beats_of_pitch(Name, A) :- note(_, beat(B), pitch(Name)), A is B.