The Copenhagen String Trio made a very agreeable Washington debut at the Corcoran last night. Violinist Kim Sjogren, violist Bjarne Boie Rasmussen and cellist Lars Holm Johansen collectively displayed an outgoing musical personality and a rhythmic vigor that were very pleasing in works of Mozart and Beethoven.

Mozart's late Divertimento, K. 563 in E-flat, was a joy of fluid string playing, paced like a long, light meal sprinkled with witty conversation. Johansen's voluptuous cello provided the work's only somber colors in the adagio, as the rest of the music buoyed happily through less than ideal circumstances: The enthusiastic audience of novices insisted on applauding after each of the six movements, and it applauded more still as a standee accidentally elbowed the light switch off and plunged the auditorium into darkness in the final allegro. No matter, the trio picked up where darkness had stopped it and breezed through the last pages. It was fun.

After intermission came a lively reading of Beethoven's Trio in G, Op. 9 No. 1. Then pianist Bodil Frolund joined the string players for Mozart's Quartet in G Minor, K. 478. Hers was an assured keyboard style, less careful of rhythms but quite strong in the outer movements. At times Frolund's eager pedaling tended to cloud Mozart's thoughts. But she was a sensitive collaborator, and the light reading the quartet received nicely matched the evening's mood.