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: If Mary were a carpenter, then Barbara is working. Barbara is working if and only if Mary is a carpenter.
If Barbara works, then Mary is a carpenter can be inferred via the biconditional elimination rule. If Mary were a carpenter, then Barbara is working can be inferred via the biconditional elimination rule.