Mathematics plus romance can appear to be an unlikely equation. But David Auburn's "Proof" shows that calculating the unknowns of love can be as difficult and complex as finding the missing variable.

Under the direction of Theatre Arts professor and actor Rhonnie Washington, three drama students explored the intricacies of relationships, family ties, mental illness and sexism, while delivering an emotionally engaging rendition of Auburn's Tony award-and Pulitzer Prize-winning play in the Little Theatre Oct. 10.

"'Proof' is an amazing relationship play," said senior Kelly Sanchez, who plays Hal, a slightly geeky grad student with an endearing academic charm and a fanatical passion for math. "It really maps the relationship between two people and is all about family."

Aside from the obvious mathematical theme that strings the characters together, the play is essentially a character study that explores the formula for love, trust and loyalty, while delving into the dark corners of human flaws and insecurities.

The story revolves around junior Whitney Thomas's character, Catherine. The troubled young woman has spent the last four years of her life taking care of her mentally unstable father, Robert (Washington), a prolific mathematician who revolutionized the field with his work.

"Proof" takes place in Chicago and commences with the appearance of Robert's spirit on his daughter's birthday, a month after the degenerated mathematician passed away.

While mourning Robert's death, Catherine is left to manage her own volatile emotions, and the valid fear that she will suffer the same predicament as her famous father.

"In some way, Catherine is trying to say no to her first love -- math," said Washington, who delivered a stellar performance of Catherine's loving father in a set of flashbacks and imaginary conversations. "She fears that she will end up like her father, a math genius who went crazy."

While the play is heavy and emotionally-laden up to this point, the appearance of Catherine's estranged sister, Claire, played by Sam Jackson, becomes a welcoming breeze of comic relief.

Claire's business suit and metropolitan demeanor offers a counterpoint to the insecure and intellectual Catherine. Claire is a stereotypical New York executive who tries to monetarily compensate for her guilt for not being there during her father's illness.

The appearance of Hal, Robert's student prodigy, adds another essential dimension to the already complex story -- the fragile line between love and trust.

"People always tell me I'm so much like the character -- geeky and dorky," Sanchez said. "Character-wise, I thought I had a great shot at the role."

With his awkward charm and whining about passing his mathematical prime at age 23, Hal not only wins over Catherine's heart, but reminds her that she is destined to carry on her father's legacy.

The plot thickens when Hal finds a ground-breaking mathematical proof among Catherine's father's incoherent notebooks, which the young mathematician believes to have been written during the one year that Robert experienced a remission of his mental illness.

When Catherine claims that the proof is her work, she is forced not only to overcome her vulnerability and fear of accepting math as her true calling, but is met with adversity from both her own sister and Hal. In a climaxing moment marked by Thomas' highly emotional performance, Catherine questions the trust of her loved ones, as well as the faith that she has in herself.

"It's mostly men who make a breakthrough in math," Washington said. "It's sexism on Hal's part because he can't wrap his head around the fact that Catherine may have written the proof."

Performing alongside his talented students, Washington stepped aside to let his students take over.

"It never occurred to me that I would be taking over a role," said Washington about taking on the role of Robert. "It's an enhanced learning experience if your professor is in the mix."

For some, acting with their professor was both exciting and unusual.

"It's been very educational and inspiring for us to work with a professional actor," Jackson said.

"It was also very sobering for us. He'd mess up and drop his lines just as much as we do, if not more," added Sanchez jokingly. "It reminds us that we are not so far away from it."

Students watching the performance felt that the rendition of the well-known play was executed quite well.

"It's a difficult play and they did a great job," said actor Ron Dritz, 61, who works in musical theater. "I loved the stage, I loved the line-up, I loved the soundtrack -- that's an amazing amount of work to pull off."

With a green light from the professionals, "Proof" definitely proves itself to be one of the great productions of the semester.

Performances continue until Oct. 18, with prices ranging from $8-$15. For more information go to http://creativearts.sfsu.edu.