Sam Rivers and Dave Holland have played jazz together on and off for 10 years. For the last three years, they have played only with each other -- either as a duo or as the core of larger groups. Last night they appeared as a duo in the first of two evenings at D.C. Space. Their unusually long and close association has created music that sounds like an intensely personal and original dialogue.

In the first set, they played for an uninterrupted hour. During Holland's acoustic bass solos, Rivers switched from sax to piano to flute. He played a tender tenor sax and a patient piano to make Holland's sliding, bending and bowed bass notes an equal partner in the sound mix. Both were technically impeccable.

The duo's professed aim is to attain true improvisation that is free of all past jazz cliches, even the unorthodox cliches of the recent avant garde. Last night they succeeded.

They worked against their own reflexive habits to create an austere music free of repetition and style but full of feeling and exploration. Each musician closed his eyes in obvious concentration, listening carefully to himself and his partner. As each lost himself in a creative trance, the music improved unmistakably as the night progressed.