The silky dynamics of pianist Ahmad Jamal's music haven't really changed throughout his career; parceling space and measuring notes in a way that echoes Count Basie and Miles Davis (whose respect for Jamal's music led him to name a tune for the pianist), he remains among the foremost jazz minimalists. Although he gained his fame in the 50s, Jamal never really belonged to either of that generation's prominent jazz waves, hard bop or cool jazz. Nor in his improvising does he pursue the extended development sought by his contemporaries. Instead his solos comprise discrete segments--many of them Jamal trademarks--which he employs the way a big band uses preset riffs, and on which he spins discriminating, slightly nuanced variations. And in stacking these segments to achieve power and excitement, he is really updating a technique almost as old as jazz itself. Jamal's idiosyncratic subtleties strike some as the very definition of jazz elegance, and others as swingingly banal; the difference depends on whether you embrace the minimalist aesthetic at the core of his music. Jamal's Chicago connections run deep; he lived here in the 1950s, and it was here that he recorded his landmark hit "Poinciana" at the old Pershing, Lounge in 1958. Thirty-four years later, in 1992, he recorded another club date in town--the impressive Chicago Revisited (Telarc)--and this extended (two-week) engagement marks his return to the scene of that triumph. Friday through Sunday and Tuesday through next Sunday, October 31, Joe Segal's Jazz Showcase, Blackstone Hotel, 636 S. Michigan; 427-4846.