Founded in 1960 by poet and Senegalese leader Leopold Senghor, Le Ballet National du Senegal performs exuberant and authentic traditional West African dances with the same hard discipline and sheer agility demanded of any other classical ballet troupe. They'll do just that, backed ably by an ensemble of Senegalese musicians. The program, called Pangols, is a reference to a tribal word that defines man's relationship to his environment.