Reasoning with "or" claims

The concept that I thought was the most interesting would have to be reasoning with “or” claims in chapter 6 of the Epstein text.  This is used after we decide if the argument is valid or weak by having a looking at the compound claim, if it has one.  A valid argument is when the premises cannot be true or the conclusion to be false at the same time, while a weak argument is when the premises can be true and the conclusion can be false at the same time. The book states that the valid argument form: A or B, not B, therefore A. This is excluding possibilities. The letters are used as claim A or Claim B.  Sometimes we can reduce the possibility. There is many possibilities with the way A or B are placed. It could A or B or C, not A, not B, therefore C.