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: John is sleeping if and only if it is windy. It is windy or Linda is poor. David is a nurse. John is not sleeping.
David is a nurse and John is not sleeping can be inferred via the conjunction rule. John is not sleeping and David is a nurse can be inferred via the conjunction rule. If John sleeps, then it is windy can be inferred via the biconditional elimination rule. If it is windy, then John is sleeping can be inferred via the biconditional elimination rule. It is not windy can be inferred via the biconditional elimination rule.