How do you achieve coherence in an art that moves through time? Throughout history composers of music have grappled with this problem, and every age has found its favorite solution, developing one or another of the structural forms that are a legacy to the contemporary composer.

The program that the Contemporary Music Forum performed at the Corcoran last night provided a well-conceived sampling of some modern solutions to this problem.

The stage was set by Elliott Carter's Sonata for Cello and Piano, an extreme example of intricate, highly intellectual structuring that involves not only thematic development and transformations, but rhythmic as well.

With all this it is also a highly charged and evocative work, and it was played with great conviction (if occasional cello inaccuracies) by cellist Evelyn Elsing and pianist Barbro Dahlman.

The other end of the scale was represented by George Crumb's "Eleven Echoes of Autumn," a hauntingly delicate, free investigation of pure sounds. Here every effort is made to avoid any hint of architectural shape. There is no rhythmic pulse, no developed themes, although ideas like descending violin slides and throbbing tones do reappear. The focus, instead, is on sound for its own sake.

In between were two offshoots. "Cuatris" by Leonardo Balada, a delightful, almost programmatic work for piano, flute, cello and clarinet, used sounds in a pictoral sense, its five short movements resembling quick sketches.

Joel Chadabe's "Street Scene" for English horn and tape is entirely programmatic, a lone personality passing through a city street full of life without every interacting with it. Its structure is its story.

The performances, as is usual for this group, were well thought out and beautifully prepared. Dahlman, as always, was anchorwoman and renewed the impression she usually makes of unusual versatility and musicianship.