What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Name the inference rule being used: Richard is a musician if and only if Patricia is reading a book. If Richard were a musician, then it is not late. It is late.
Richard is not a musician can be inferred via the modus tollens rule. If Richard were a musician, then Patricia is reading a book can be inferred via the biconditional elimination rule. If Patricia reads a book, then Richard is a musician can be inferred via the biconditional elimination rule.