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: It is not cloudy. If it is cloudy, then Patricia is a writer. If Patricia were a writer, then it is cloudy. Patricia is a writer if and only if Barbara is working.
Patricia is not a writer can be inferred via the modus tollens rule. It is cloudy if and only if Patricia is a writer can be inferred via the biconditional introduction rule. Patricia is a writer if and only if it is cloudy can be inferred via the biconditional introduction rule. If Patricia were a writer, then Barbara is working can be inferred via the biconditional elimination rule. If Barbara works, then Patricia is a writer can be inferred via the biconditional elimination rule.