After a sabbatical of nearly two years, this New York trio has pretty much picked up where it left off. While the stripped-down music of bassists Sasha Frere-Jones and Wilbo Wright and drummer Clem Waldmann remains rooted in the early-80s avant-funk of ESG and Liquid Liquid, computer editing and an expanded instrumental palette that includes guitar, electronics, horns, and keyboards have made the last couple records--1998's Lifelike and the new EP, The Iron Apple, both on Southern--harder to pin down than earlier recordings. The Iron Apple (named in tribute to the late apple farmer who let the band practice in his Pennsylvania cider house) opens with "Mrs. Lady Lady," one of the group's most detailed and articulate tunes: a busy but infectious groove is overlaid with a gnarled synth melody, gentle guitar arpeggios, upright-bass counterpoint, brittle six-string-bass funk, and what sounds like washes of accordion. Flecks of dub and prog rock drift in and out, adding complexity but rarely disturbing the hypnotic sense of propulsion. From there on out the disc is pretty much an exercise in theme and variation: "Ms. Lady" is a remix, isolating elements of the first track and moving them around in a beatless setting. The other three pieces are "Blue Pietro," "Golden Pietro," and "Run, Pietro," but I have no idea which, if any, is the "original." I'm not sure how Ui will pull this concept off onstage or if they'll even try, but they've proven before that their tough rhythmic attack alone can carry a show. Friday, 5 PM, Reckless Records, 1532 N. Milwaukee; 773-235-3727. Friday, 10 PM, Empty Bottle, 1035 N. Western; 773-276-3600.