For the dramatic substance that gives each bill distinction, you must wait, in both cases, nearly to the end. Lynn Nottage's Banana Beer Bath (Program A), a monologue played with stunning exactitude by Elain Graham, describes a near-miraculous rescue, darkened by bitter grief, with the seemingly artless straightforwardness of a folk tale. Kia Corthron's more self-consciously cunning Dialectic, which closes Program B, postulates a debate, in the afterlife, between an abortion-clinic client and an anti-abortion terrorist. Don't, in either case, expect predictability. In playwriting as in other arts, it's not ethnicity or gender but imaginative power that breaks the routine.