"The quality of an idea or a technique or even a piece of equipment that attracts me," the British guitarist Derek Bailey has stated, "is its malleability." His own ideas and techniques, and even the contexts in which he makes music, bear this out. His guitar style is a primer on "extended technique": the inclusion (and frequently the invention) of unorthodox practices to obtain sounds outside what we expect to hear from a given instrument. Indeed, Bailey supplements his spartan tone and explosive linear outbursts with a collection of scrapes, scratches, pinches, and thuds. (His legacy extends directly to younger guitarists Henry Kaiser and, to a lesser degree, Fred Frith.) Following such impulses without regard to "career" considerations, Bailey (along with saxophonist Evan Parker) has served as a guiding beacon for the British progressive music community since the mid-1960s. His stature stems in no small part from Company, the free-improvisation, freely arrayed concert format he created in 1976, which has attracted such musical heavyweights as Misha Mengleberg, Steve Lacy, Dave Holland, and even Bill Laswell. Bailey presents an annual Company event in London and occasionally takes it on the road; this weekend Company's coming to Chicago for the first time. Friday night will focus on solo guitar and duos starring Gregg Bendian, a percussionist and composer no less daring for his rigorous attention to formal detail. On Saturday night and Sunday afternoon, this open-ended musical discussion continues with a midwest cast, including legendary Art Ensemble of Chicago saxophonist Roscoe Mitchell; reedman Gene Coleman, equally at home in jazz and new-music contexts, who'll perform exclusively on bass clarinet; classical violinist Dorothy Martirano; and guitarist Jim O'Rourke (along with Bendian). Friday and Saturday at 9 and Sunday at 3, HotHouse, 1565 N. Milwaukee; 235-2334. Saturday afternoon Bailey conducts an improvisation workshop (it's $40; to enroll call 227-2215).