Bryan Lopez's charm seems key to enjoying the Playcrafters Barn Theatre's production of Proof. That's not to say that he's the only reason to take in director Steve Parmley's presentation of author David Auburn's material, but I do want to acknowledge that it's his character's grace and agreeableness that draw you into the play, as he's our sympathetic and likable connection to the plot's proceedings. During Friday's performance, the eagerness with which Lopez's Hal tried to lure Stephanie Moeller's Katherine out of her house to hear his band of math geeks perform held such sincerity that I hoped she'd say yes solely for his sake.