It’s around the middle of the first act when you realize that, yes, David Auburn’s Pulitzer- and Tony-winning Proof is indeed a good, entertaining play. With a swift plot and the right mixture of the comic and the dramatic, Proof competently dissects familial relationships.

Playwrights and filmmakers have often examined the link between madness and genius, most recently looking at those with great artistic talent (Picasso, Jackson Pollock) and mathematical ability (John Nash). The consensus seems to be that from the same propensity for great intellectual achievement comes emotional and mental instability, the power of revolutionary ideas burning out the frail body and brain of the conduit. David Auburn picks up this idea and tracks, not the impact of madness on the genius, but the impact of the genius’ madness on those around him.

The play’s central character, Catherine, has spent years caring for her father, who was the world’s pre-eminent mathematician before his mental illness and death. The play opens on the eve of Catherine’s 25th birthday, when she must deal with the loss of her father, the arrival of her older sister Claire, and the sneaky Hal, one of her father’s Ph.D. students. When Hal finds an old notebook among Claire’s father’s papers containing an astonishing, undiscovered mathematical proof, determining its authorship tests the bonds between the two sisters and between Catherine and Hal, who have developed a romantic relationship. Catherine claims she discovered it but Claire thinks it is their father’s work, leaving Hal in the middle, seeking to discover the true author.

Set entirely on the back porch of the family home, the largely dramatic script is interspersed with humour so that the audience is never bogged down by the tensions between the characters. Auburn gets in many, but not too many, jokes about the secret party life of math geeks.

As the distraught younger daughter, Jennifer Paterson plays Catherine with humorous frumpiness. She contrasts well with Tamara Bernier (Claire), who is slick but unsubstantial. Bernier plays a clichéd big bad city girl, but adds depth by hinting at the bitterness she feels at not having Catherine’s intelligence or the special connection with their father that came with it.

The play raises the question of how we judge a person’s mental soundness, and doesn’t come up with a satisfactory answer. All three characters are constantly equating the father’s mental stability with his ability to work. The possibility exists that, while he may not be able to churn out ground-breaking formulae anymore, the father may have recovered his sanity. But his daughters and his student seem only interested in his intellectual worth, making them seem heartless when accompanied by the fact that none of them show much grief. They are all more eager to move on than to remember.

Photograph by David Cooper