The music of pianist Monty Alexander clearly shows the influence of several true jazz legends, but I place more importance on his proven success in absorbing their lessons. Lots of pianists have displayed the influence of Oscar Peterson's relentlessly swinging, seamless bebop lines, for instance, but bassist Ray Brown and vibraphonist Milt Jackson--both longtime associates of Peterson--have each used Alexander in their own groups for extended periods. Many musicians speak highly of the deceptively light touch that Nat "King" Cole brought to the piano; Alexander has incorporated enough of Cole's muse to structure a fairly successful onstage tribute, replete with his own similarly dry and wispy vocals. While he doesn't flash it around, he has a keen appreciation for the spirit (if not the letter) of Art Tatum's rococo stylings, and the calypso music that formed the first impressions of his Jamaican childhood comes frequently to the fore in his sets. Despite that, Alexander is more than the sum of these parts; he stitches together his various influences with sharply etched harmonies and a fearless technique, and interlaces even straight-ahead tunes with a rhythmic bounce derived from his Caribbean roots. A last-minute replacement for the seriously ill Joe Pass, Alexander offers a cheering presence that will no doubt soar higher thanks to the Jazz Showcase's new seven-foot grand. Through Sunday, Joe Segal's Jazz Showcase, Blackstone Hotel, 636 S. Michigan; 427-4846.