It's that breed of verbal swordplay that so impresses on stage while seeming so redundant and brittle on screen.

... Proof seems like no more than a fraction of a cinematic experience, a string of emotional calculations that fails to provide a satisfying solution.

Madden stages the action with a minimum of imagination and gets a career-worst performance out of Davis in a key role, but the material still sputters to life on the strength of the writing and Paltrow's commitment to the part.

An unlovely film about an unlovely group of people.