Jazz pianists Marion McPartland and Dick Hyman and classical pianist Ruth Laredo explore the borderland between composed and improvised music in Three Piano Crossover at the Carpenter Center Jan. 29. "The point of the trio is to show what classical and jazz piano have in common, to blur the distinctions," say Hyman. The three musicians bring strong credentials in their respective disciplines. Dick Hyman's nearly half-century career is the embodiment of "crossover," with more than 100 recordings released under his own name, and many more in support of other artists. His work includes compositions for large and chamber ensembles, accompaniment of vocalists from Tony Bennett to Barry Manilow, and film scores including "Moonstruck" and many Woody Allen films. There is a lot of variety, but a common foundation. "For me," Hyman says, "jazz piano is the fundamental thing," Marion McPartland's is one of the most recognizable voices in jazz. She has done much to bring a wider audience to the music through her informal and informative weekly program on National Public Radio, "Piano Jazz." "She keeps a very heavy performance schedule," Hyman says with admiration. Most recently she appeared for several days at the new Penthouse at Lincoln Center, playing completely improvised sets with characteristic elegance and grace. Ruth Laredo made her reputation playing the piano works of Rachmaninov and Scriabin. (Now being rereleased on CD.) "I'm not an improviser, Laredo admits. "Classical improvisation has become a lost art, there are very few people who can do it." But she is masterful at working within the structure of notated music. And, Hyman says, "she plays a mean boogie-woogie." The three originally joined forces for part of New York City's acclaimed Jazz in July series, for which Hyman is artistic director. "We are all fans of each other," Hyman says. "The idea is based on Ruth's appearance on Marion's Piano Jazz program. Ruth would play one of her classical things, and Marion would improvise. From that we all got the idea, and mounted it as a performance." Since then, the trio has performed throughout the United States and in Europe. "It's very enjoyable, the performance is different every time," Laredo says. The atmosphere of the concert is anything but stuffy. "We talk to each other it's quite informal and relaxed." The program is divided into two parts, each consisting of a series of solos and duets. The music is drawn from jazz standards and the classical cannon, with thematic groupings, including Latin music and the blues. Sometimes surprising parallels are revealed. Antonio Carlos Jobim's bossa-nova hit "Wave" shares a melody with a Chopin prelude; the theme from an intricate and beautiful Scriabin piece is reincarnated as "Stella by Starlight." One section of the program consists of the pianists playing portraits of each other. The late, great George Shearing wrote the pieces for McPartland and Hyman. McPartland improvises a new portrait of Laredo for every performance. "One version was written down," Laredo recalls. "Marion says she'd like to play it again sometime." Each set climaxes with all three pianists playing together: "Caravan" in the first half, Thelonious Monk's "Straight No Chaser" in the second. "While we play for each other" Hyman confides, "we really play for the audience. We take them into our confidence and share our thoughts."