Weve had more than our share of realistic living rooms in this theater season: living rooms of the rich and famous, living rooms of the poor and obscure, living rooms in Manhattan and London and Paris. As for real innovation in set design, well, for that there was Scott Coopers intrepidly abstract environment for Caryl Churchills A Number. Coopers daring set consisted of a tilted, circular stage behind which were colored panels in a modernistic array evoking, for a play about cloning and multiple selves, the sense of a world whose soul was increasingly mathematical. In this bizarre, unsettling space, a man named Salter confronted his three sons only one of whom was biological and tried to find peace in a world out of balance. Did the last century of innovation in set design occur or not? Thanks to Cooper, we can now say: maybe.