With speed at an ever-increasing premium in so many pursuits, it was probably inevitable that such acceleration would come to bear on music composition. Such is the rationale behind the Rapido! composition contest, the northeast regional semifinalists of which were premiered by Boston Musica Viva and conductor Richard Pittman in their Friday night season-opening concert.

The contest's parameters — a mere fortnight between the announcement of a theme (dance, this year) and an instrumentation (violin, cello, oboe, and piano) and the deadline for entries — practically ensures some measure of musical sketchiness, but also reveals a composer's priorities: Each of Friday's three works was impressive and unfinished in individual ways.