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 cooking if and only if Barbara is a sailor. If Richard doesn't cook, then Michael is playing a game. Barbara is not a sailor.
If Richard cooks, then Barbara is a sailor can be inferred via the biconditional elimination rule. If Barbara were a sailor, then Richard is cooking can be inferred via the biconditional elimination rule. Richard is not cooking can be inferred via the biconditional elimination rule.