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 Joseph were a lawyer, then James is a nurse. It is not windy. If Charles were not an astronaut, then Joseph is a lawyer. Charles is an astronaut if and only if it is windy.
If Charles were not an astronaut, then James is a nurse can be inferred via the transitivity rule. If Charles were an astronaut, then it is windy can be inferred via the biconditional elimination rule. If it is windy, then Charles is an astronaut can be inferred via the biconditional elimination rule. Charles is not an astronaut can be inferred via the biconditional elimination rule.