Reprinted from yesterday's late editions.

Guitarist Jim Hall and bassist Red Mitchell, who opened Monday night at Blues Alley for a three-night engagement, demonstrated what jass is all about - spontaneity, surprise and subtle interplay.

Banking on a friendship that dates back 22 years, the duo personified a chamber jazz sound. The pair also showed that two superb jazz men can play rhythm for each other. Each is a master of the shadings of color and dynamics. At times, they played with the roar of a large ensemble, and there were moments when they sounded like the duo they were.

Much of the first set, performed before a half-full quiet house in the 200-seat club, was made up of improvisations on popular standards. They took songs like "There Is No Greater Love," "Time After Time" and "Embraceable You" and transformed them into fresh views of the familiar.

The current engagement marks a reunion of the two old friends. Until recently, Mitchell had been living in Stockholm since 1968 in protest of the war in Vietnam and the barren jazz scene in this country. Hall had been working in recording studios. To our benefit, they have decided to perform together - for how long, they don't know.