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: If it is sunny, then Robert is reading a book. Patricia is cooking or it is sunny. If Patricia cooks, then Robert is reading a book. If Robert reads a book, then Patricia is cooking.
If it is sunny, then Patricia is cooking can be inferred via the transitivity rule. Robert is reading a book can be inferred via the disjunction elimination rule. Patricia is cooking if and only if Robert is reading a book can be inferred via the biconditional introduction rule. Robert is reading a book if and only if Patricia is cooking can be inferred via the biconditional introduction rule.