Chandler, Joe, Monica, Phoebe, Rachel, Ross celebrated at the restaurant Ross' promotion. After a couple of days, they remember:
Chandler: “Joe sat to my right”.
Joe: “To my right sat Phoebe“.
Monica: ”To my left was Rachel“.
Phoebe: ”I sat to the right of Chandler”.
Rachel: ”To my right sat Ross.”.
Ross: ”I sat to the left of Monica”.
Exactly 2 of them are lying.
I need to translate this problem into FOL. Next, I need to prove 2 theorems from the scenario above using resolution algorithm.
My question is, What is classified as a theorem? Is it a theorem the fact that to Rachel's right Ross was sitting, or that, for example, Chandler is lying?