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: Karen is a taxi driver if and only if Thomas is playing squash. If Charles were a nurse, then Thomas is playing squash. It is cloudy or Karen is a taxi driver. It is not cloudy or Charles is a nurse.
Karen is a taxi driver or Charles is a nurse can be inferred via the resolution rule. If Karen were a taxi driver, then Thomas is playing squash can be inferred via the biconditional elimination rule. If Thomas plays squash, then Karen is a taxi driver can be inferred via the biconditional elimination rule.