初次适用prolog

# writer(A, B) A是书B的作者
writer('Kenneth', 'C').
writer('Brice A.Tate', 'Seven').
writer('Harold Abelson Gerald', 'SICP').
writer('BobDay', 'a').
writer('BobDay', 'b').

# musician(A, B). A会弹奏B
musician(a, guiter).
musician(a, piano).
musician(a, drum).
musician(b, piano).
musician(b, violin).
musician(c, guiter).

# style(A, B). A的音乐风格是B
style(a, flexible).
style(b, classic).
style(c, pop).