Bill Evans, who turns 65 in a matter of days, is still performing at an age when other dancers have long since retired. Trained in ballet, modern, and jazz, he revolted against the discipline of holding in his stomach (which inhibits deep breathing) and "working through" injuries (i.e., ignoring them) at about 30, when he realized that chronic physical problems were threatening his career. He started thinking about what it felt like to tap-dance as a kid (at the age of three he put marbles between his toes so he could sound like Fred Astaire), remembering his free flow of movement and lack of concern about how he looked. Then he put those principles to work in his modern dance company, founded in 1975, coming up with the now widely used "release technique" for modern dancers. Years later, in 1992, he started a tap-dance troupe. Now Chicago Tap Theatre artistic director Mark Yonally--who performed in Evans's company and who detailed Evans's evolution in Dance Spirit Magazine five years ago--has brought his teacher and mentor here for a tribute to his work. When Evans toured India in the mid-90s he found that audiences really responded to the pure rhythms of tap dance; one work he's performing here is How to Name It, a certified oddity that incorporates mudras and bharata natyam-style gestures. Also on the program are a number of Evans's other dances, both solos and ensemble works, plus some from Yonally's repertoire and his new piece honoring Evans, which includes a paean to stillness and silence. Fri-Sat 4/1-4/2, 8 PM, Harold Washington Library Center, auditorium, 400 S. State, 773-655-1175, $15-$25.