David Auburn’s “Proof,” which won a Tony and a Pulitzer and is making its Utah debut at Pioneer Theatre Company, is a play that would be difficult to ruin. The script is deceptively simple, brightly funny and often quite touching. If the four actors performing it are even competent, the brilliance of Auburn’s words will shine through.

At PTC, the actors are more than competent, and Charles Morey’s direction is steady. The Broadway production is not appreciably better than this one; you would do well to see it and save yourself a trip to New York.

The story is of Catherine (Michelle Six), whose father (Noble Shropshire) has died a week before her 25th birthday. She knows she inherited much of her father’s considerable mathematical genius; she fears she may have also gotten some of the less savory aspects of his personality. The insanity, for example.

At present, one of her father’s best students, a jittery graduate student named Hal (Joey Collins), is going through the old man’s notebooks. Many are filled with ramblings; Hal feels compelled to determine whether there’s anything valuable in there. In his day, Catherine’s father was a legend among mathematicians. To overlook any of his final contributions would be a shame.

What is in the notebooks becomes an issue in the second act, but the play’s focus remains on Catherine. With sardonicism heightened by her self-consciousness at being, at this point in her life, completely directionless, Catherine isn’t afraid to cut people down with withering remarks. It is her only defense against her well-meaning but ineffectual sister, Claire (Gloria Biegler), who fears Catherine’s going insane even more than Catherine does.

Michelle Six carries the play as Catherine. She has affected a screechy voice that is somewhere between “precocious little girl” and Roseanne Barr, but she uses it to nail every one of her lines, from the witty to the sad. Her range is impressive.

Gloria Biegler is well-grounded as Claire, and Noble Shropshire — seen in flashbacks and imaginations as Dad — conveys fatherhood, genius and encroaching madness all at once.

I am less pleased with Joey Collins, who overdoes Hal. Collins’ attempts to make the character seem awkward and nerdy have instead caused him to sound like the sort of person who ought to be saying “dude” a lot. There are people who speak and act like this, but Collins does not seem like one of them, nor is Hal written to be one. Collins is funny, and he grows on you, but his interpretation lessens the character’s potential.

No matter, though. Auburn’s words — well-chosen, conversational and effective — are what constitute the play’s greatness. They allow for humor in the midst of pathos, without ever seeming to “set up” a joke. They draw us in with hints of dramatic intrigue, and keep us listening because we can’t bear not to know what will become of these people. Conveyed to the audience with compassion and skill, the words of “Proof” will ring true.

Should you go? Yes. It is smart but accessible to casual theater-goers, too.

I saw this show on Broadway in 2000 and remarked then that it was "mathtastic." The PTC production was just about as good.