Abstract: A composition conditioning system selects a music structure from a music structure database. The selected music structure specifies a first condition of music composition. A style input specifies a second condition of music composition. A melody rhythm composer retrieves, from a rhythm pattern database, an appropriate rhythm pattern for the composition condition. A chord progression composer retrieves, from a chord progression database, a suitable chord progression for the composition condition. A melody pitch composer generates a pitch candidate for a new melody note from an old melody note pitch and a current music progression (tonality and chord). A pattern recognizing module analyzes a melody up to the candidate into a melody pattern. A test module searches through a melody pattern rule base for the analyzed melody pattern.