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: It is raining or Charles is a lawyer. Robert is a carpenter if and only if it is raining. Robert is not a carpenter.
If Robert were a carpenter, then it is raining can be inferred via the biconditional elimination rule. If it rains, then Robert is a carpenter can be inferred via the biconditional elimination rule. It is not raining can be inferred via the biconditional elimination rule.