SIerra Stages presents Proof, May 1st -18th at Off Center Stage in Grass Valley. A special presentation of the Tony Award and Pulitzer Prize-Winning Play. David Auburn’s PROOF is an elegant and engaging story of passion, genius, and family bonds. Catherine has inherited her late father’s mathematical brilliance, but does she also share his madness? When one of his graduate students discovers a groundbreaking proof among the professor’s notebooks, Catherine must face the legacy her father has left behind.