Catherine has inherited her late father’s mathematical brilliance, but she is haunted by the fear that she might also share his debilitating mental illness. She has spent years caring for her now-deceased father, and upon his death, she feels left alone to pick up the pieces of her life without him. Caught between a new-found connection with Hal, one of her father’s former students, and the reappearance of her sister, Claire, Catherine finds both her world and her mind growing increasingly unstable. Then Hal discovers a groundbreaking proof among the 103 notebooks Catherine’s father left behind, and Catherine is forced to further question how much of her father’s genius or madness will she inherit. Winner of the Pulitzer Prize for Drama, David Auburn’s Proof is a passionate, intelligent story about fathers and daughters, the nature of genius, and the power of love.
Catherine - A young woman, 25 years old, who inherited much of her father's mathematical genius, and, she fears, his "instability" as well; she gave up her life and schooling to take care of her father until his recent death.
Claire - Catherine's older sister, a practical and business-minded woman who has been comfortably successful in her work and relationships. She left Robert and Catherine behind, distancing herself from the run-down family home of her youth. She left the family to make a new life for herself in New York City. (29 to 35)
Robert - A recently deceased mathematician praised for his groundbreaking work in his youth, but whose later years were plagued by delusional mental illness; he is seen in Catherine's imagination and in flashbacks. (50s-60s)
Harold (Hal) Dobbs - One of Robert's last Ph.D. students during the one year his idol and mentor's illness went into remission, at least enabling Robert to teach, if not continue his own creative mathematical work. Late 20s.