Jarrett's classical debut

A third of Symphony Hall was empty last Friday for the classical debut of improvisational keyboard luminary Keith Jarrett. And more's the pity. A demanding, if slightly lopsided, repertoire of Scarlatti, Bach (both J.S. and C.P.E.), Beethoven, and Shostakovich showed Jarrett to be both keenly interpretive and technically sterling over a broad range.

Not that he was flawless. He lost his way in the Courante movement of Bach's French Suite (G major, No. 5) and had to start over. He muddied some fast passagework in both Bach and Scarlatti. And he out-and-out hit wrong notes in the Adagio of Beethoven's ''Pathetique,'' where right hand alternates melody back and forth with the left hand.

But overall, this performance showed supreme confidence, coupled with an almost childlike reserve not to take chances with tempo and phrasing. These were pure, almost raw interpretations, lacking romantic embellishment - almost as if the established master of improv needed to prove he can take on the discipline of sticking tightly to someone else's time-honored texts. Which is exactly what he must do now, alongside pianist heavyweights from Ashkenazy to Watts.

That proof will be a long time coming. But based on his performance - and hints of his cocky, self-assured presence - you get the feeling he can, and will , do anything he sets his mind to.