Eavesdropping on two generations. `Checkmates' shows black couples coping with ever-changing times

Checkmates Comedy by Ron Milner. Directed by Woodie King Jr. Stars Paul Winfield, Ruby Dee, Marsha Jackson, and Denzel Washington. ``Checkmates,'' at the 46th Street Theatre, presents an entertaining case for the proposition that two plus two produces dramatic equilibrium. With the aid of a splendid acting quartet directed by Woodie King Jr., Ron Milner illustrates how changing times have molded the experiences and differentiated the expectations of two black couples representing successive generations. While the tone is prevailingly comic, Mr. Milner covers a fairly wide emotional range, particularly in his emphasis on the poignant cost of success to his upscale young achievers.

Detroit (``or just about any other American metropolis,'' as the program says) provides the urban milieu for ``Checkmates.'' Young marrieds Sylvester Williams (Denzel Washington) and Laura McClellan-Williams (Marsha Jackson) rent the upstairs apartment of a pleasant two-family house owned by Frank and Mattie Cooper (Paul Winfield and Ruby Dee), who occupy the ground-floor flat.

The Williamses are beginning to make it in a world undreamed of by their more down-to-earth elders. Laura sees her promotion to buyer as merely the first step to future entrepreneurship. Sylvester is wheeling and dealing his way upward in the retail liquor business. Apart from their brief but intense sexual encounters, however, their driven self-preoccupation gradually alienates them from each other. Sylvester's belated discovery that his wife has had an abortion rather than risk damaging her career signals the approaching end of a troubled relationship.

Contented veterans of a 45-year marriage, Frank and Mattie are more than merely two bemused observers of an incomprehensible younger generation. Frank returned from World War II to find that his service had earned him no compensating opportunities in a racist America. While accepting low-paid menial employment, he put his Army-acquired construction knowledge to work and became a successful contractor, a business from which he has retired. Though both Frank and Mattie have been briefly unfaithful, their loving partnership has survived and deepened as they have become parents and grandparents.

Milner alternates between the two households with considerable adroitness. While the Williamses' drama unfolds in the present, Mattie and Frank's past emerges through a series of flashbacks. Under Mr. King's guidance, Miss Dee and Mr. Winfield make the transitions easily, using the recollected scenes to enrich their warm and appealing characterizations. Equally effective in a contrasting way are Mr. Washington - as physically nimble as he is eloquent - and Miss Jackson, whose determined but bewildered young career woman discovers that her ideas of a shared partnership aren't shared by her partner. As the dialogues unfold, Mattie finds herself befriending Laura, while Frank and Sylvester have a wonderfully funny scene of conversational cross-purposes.

Edward Burbridge's trim scenic design places the Cooper and Williams premises side by side on the stage, leaving the spectator to imagine the upstairs-downstairs configuration. The attractive production was costumed by Judy Dearing and lighted by Ronald Wallace.