Avant-garde art seems to revolve around The Concept. The concept is not only an idea, it's a motivating force, an animating entity that gives form and substance to the artistic product. At times, it is the artistic product -- for better and worse.

Composer Rhys Chatham's is reductionism -- as in reducing compositions to certain basic rhythmic and sonorous levels or textures, as in playing the same basic musical idea for three-quarters of an hour.

His show at the 9:30 club Saturday night began with Chatham hammering out dissonant chords on his electric guitar while a drummer attempted (unsuccessfully) to maintain a steady beat. The remainder of the performance featured Chatham and four additional musicians hammering out dissonant chords on their electric guitars while the drummer attempted (unsuccessfully) to maintain a steady beat.

At the core of this electronic mishmashery was the notion that instrumental and rhythmic structures have an intrinsic power of their own, that complexity is possible within a simplistic setting, and, no doubt, several other intriguing ideas.

Whatever. Chatham's performance failed to engage the mind, the feet or the soul. Perhaps it was a good concept, badly executed . . . or possibly, it was a bad concept, badly executed . . . or, zzzzzzzzzzz . . .