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: David is fast if and only if Michael is a nurse. If it is cloudy, then Michael is a nurse. If David were fast, then it is cloudy.
If David were fast, then Michael is a nurse can be inferred via the transitivity rule. If David were fast, then Michael is a nurse can be inferred via the biconditional elimination rule. If Michael were a nurse, then David is fast can be inferred via the biconditional elimination rule.