Masterful composer, conductor, and thinker Pierre Boulez died in January 2016 at the age of 91 after decades of revolutionizing classical music and propelling it to radical new extremes. As a conductor he had a long, fruitful relationship with Chicago, beginning with a two-week subscription series leading the Chicago Symphony Orchestra in 1969, during which his piece Livre Pour Cordes received its U.S. premiere. Nineteen years passed before he conducted the CSO again, but beginning in 1993 Boulez began making annual visits that continued until 2010, displaying his sophisticated aesthetic with programs that balanced new work with 19th- and 20th-century staples. It’s fitting that this homage to his genius as part of the MusicNow series includes two later works, both of which used materials from earlier compositions. Derived from Répons (1981) and Messagesquisse (1976-77), Dérive 1 (1984) is a short sextet piece with an opening six-note chord that serves as a kernel for several ravishing minutes of fluttering piano, flute, clarinet, violin, vibraphone, and cello. Mémoriale (1985) expands a passage from his 1972 trio work  . . . Explosante-Fixe . . . into a haunting, tension-riddled octet marked by impressionistic flute. The solo piano work 12 Notations (1945) is a rigorous study that draws upon serialism and demands a vibrant percussive touch. The program is rounded out by two world-premiere commissions: For Two or Three Instruments, one of the last works from the brilliant Pauline Oliveros—who died last November—and Shadows of Listening, a piece by former Chicagoan Marcos Balter that serves as an homage to both Boulez and Oliveros.   v