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: Linda is a taxi driver if and only if it is overcast. If Karen were a carpenter, then Susan is not poor. If Linda were a taxi driver, then Karen is a carpenter. Susan is poor.
Karen is not a carpenter can be inferred via the modus tollens rule. If Linda were a taxi driver, then Susan is not poor can be inferred via the transitivity rule. If Linda were a taxi driver, then it is overcast can be inferred via the biconditional elimination rule. If it is overcast, then Linda is a taxi driver can be inferred via the biconditional elimination rule.