There may be no more exciting pianist in jazz than Marilyn Crispell. Perhaps you (like me) hate statements that bold--especially about someone you've never heard of; the proper response would be to check her out tomorrow and see if I'm not right. Crispell can boast an impressively clearheaded musical vision that is particularly well served by her explosive technique. As is always the case with a pianist working on the "free jazz" frontier, Crispell begs comparison with Cecil Taylor, the grand master of unconventionally structured improvisation; in fact, Crispell herself lauds Taylor as an inspirational influence. But while she uses the crashing note clusters, the aggressive cross rhythms, and the mercurial attack that you'd identify with Taylor, Marilyn Crispell really has a different idea altogether. Her structures are more transparent; she hears a wider range of melody; and, as she has stated, "I'm not really interested in playing free jazz per se; I'm interested in playing against different rhythms that don't have to lock into a groove. Even when they don't, Crispell's music has an ineradicable rhythmic strength that alone is worth the price of admission. She appeared at Ravinia in August as part of Anthony Braxton's quartet; her return marks her solo-piano debut in Chicago. Saturday, 8 PM, Elbo Room, 2871 N. Lincoln; 667-1469 or 549-5549.