The music of Viennese composer Karlheinz Essl is a case study in the disintegration of boundaries between improvisation and composition. On the 1995 compilation Rudiments (TONOS), which includes several examples of his imaginative abstract writing (“Met Him Pike Trousers,” “Helix 1.0”), Essl travels easily between the two modes, particularly on “Close the Gap,” a composition for three tenor saxophones. Though it’s driven by an unmistakable logic, the piece nevertheless reveals many hallmarks of the extended technique practiced by improvisers–the percussive pops, the legato arcs, and the staccato unisons. For his Chicago debut, with local composer and clarinetist Gene Coleman and his Ensemble Noamnesia, Essl will present several improv-based compositions. These include two versions of his 1998 piece “Champ d’Action,” the first with saxophonist Jeremy Ruthrauff, bassist Michael Cameron, and percussionist Steve Butters, and the second with flutist Lisa Goethe, oboist Kyle Bruckmann, Coleman on bass clarinet, and Jeremy Ronkin on French horn. The musicians will be “conducted” by Essl, via a network of laptops, with graphic, verbal, and notated instructions; they’ll be given 30 seconds to assimilate these into the performance, and their contributions must be sensitive to what the other musicians are playing at the time. Also on the program is a piece called “Flock,” whose score is basically a timetable that tells the musicians (Ronkin, Butters, Essl on electronics, clarinetist Mwata Bowden, and bassist Harrison Bankhead) when to improvise. Admission is free. Sunday, 3 PM, Chicago Cultural Center, 78 E. Washington; 312-744-6630. PETER MARGASAK

Art accompanying story in printed newspaper (not available in this archive): photo by Ali Schafler.