It's possible that I'm not understanding the diagram and their reasoning, but I wanted to check with some people here before I come to a conclusion. 1. The problem statement, all variables and given/known data 2. Relevant equations 3. The attempt at a solution I don't understand why the book says the formula is false, yet there is a "T" at the bottom of the computation. The book is, Understanding Symbolic Logic, 5th ed. by Virginia Klenk.