Writing the program for Friday night's Twilight concert at the Pa Acacemy of Music becomes a bit of a challenge when the performance is jazz pianist David Leonhardt. How do you pin down a guy who thrives on spontaneity and musical improvisation? Well, you don’t. Kristin Young, associate dean at the academy came up with a working solution. “We’ll just put “Selections may include...’,” she explains. Because basically, what Leonhardt plays all depends on how Leonhardt feels at the time. There’s never any knowing where he and his musical maverick side-kicks will go. “I think that will be interesting for the audience. It leaves you in suspense,” she adds. The David Leonhardt Jazz Trio performance is the second of eight Twilight Series concerts scheduled at the academy through May, 2003. Leonhardt was in town most recently in June to perform at Long’s Park’s Jazz Sunday. But his improvisational tendencies make the jazz man’s performance a bit different than most at PAM. “Dave Leonhardt is an extremely versatile musician,” says Young. “Having him here offers a different musical experience.” Still, she says, there’s not that big a leap from classical to jazz. “Many jazz musicians are trained both classically and in jazz. It’s interesting to see how the two genres overlap and how you can really learn from both.” Plus, the interplay so evident between jazz musicians is common between chamber musicians, as well, says Young.