I am interested in the concept of how music is created based on structures and rules but also those boundaries are constantly being tested throughout music history. Music composition became much less restricted by rules and structures in the Romantic period than the earlier Classical and Baroque period. And later came Schonberg's twelve-tone music and minimalists' process music in the early 20th century. Avant-Garde musicians continuously challenge the definition of music and progress the way music is perceived by breaking old traditions and inventing new rules.
There is a spectrum between predictability and variability when we judge a piece of musically pleasing or not. Musicians and listeners can fall anywhere on this spectrum, which determines a musician's style and listener's tastes.