What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? If Robert were a janitor, then Barbara is a lawyer. Linda is an astronaut if and only if Barbara is a lawyer. Robert is a janitor if and only if it is snowing. If Linda were an astronaut, then it is snowing.
If Linda were an astronaut, then Barbara is a lawyer. If Robert were a janitor, then it is snowing. If Barbara were a lawyer, then Linda is an astronaut. If it snows, then Robert is a janitor.