Few things in music are as dramatic as a true give-and-take dialogue between talented musicians. Last night Keith Jarrett opened a four-day jazz festival with a full evening of solo piano improvisations. But a fascinating musical diaglogue developed between Jarrett's left hand and his right.

Jarrett entered the black-curtained stage's only spotlight dressed in jeans and jogging shoes. After running in place to loosen up and bowing his head to concentrate, his right hand fingered a chord to begin a 45-minute chain reaction of tabla rasa improvisations.

His left hand hammered out repeated figures like a fool's rhythm section. His right hand would begin everchanging melodic themes only to return to the original chord with the musical tension still taut. A lush Debussy-like passage followed: the left hand anchored it in somber chords while the right hand rippled through quick triplets. Then came a hypnotic drone section in which tightly clustered arpeggios held by the pedal created an unusual organ tone.

Finally came a stomping blues section where each hand challenged the other with rhythmic variations on the catchy chord phrases. Jarrett rose out of his seat to play standing up while twisting and turning to the music. He even sang in a wordless cry.

In recent interviews, Jarrett has come off as a pompous, pretentious "artistie." But last night he created music that was bravely adventurous and richly generous.