If jazz and modern dance were once like rebellious teenagers breaking their classic parents' rules, then improvisation was their slang, a common language that took them far past the old ways of expression and into the future. It comes as no surprise that these two forms continue to speak that language as they emerge into their "adulthood," and B>Trisha Brown Company$>'s upcoming critically acclaimed jazz trilogy uses movement to echo the kind of planned spontaneity that underlies the music. Brown's three-part collaboration with jazz trumpeter Dave Douglas was launched in I>Five Part Weather Invention$> in 1999, and continued with I>Rapture to Leon James$>, a work inspired by the famous lindy hopper and Savoy Ballroom dancer Leon James. The full trilogy, including the final unnamed work, will run Thursday, June 29, through Saturday, July 1, in Page Auditorium on Duke's West Campus. Aficionados should also check out the seminar about modern dance and jazz the choreographer and composer will be leading on July 1 at 11 a.m. in the Nelson Music Room on Duke's East Campus. Performance tickets are $34, $25 and $19\m>call 684-6444. For more information on ADF, call 684-6402.