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 Robert drives a car, then Mary is cooking. For all x_14, if x_14 were a politician, then x_14 is driving a car. Barbara is sad or Robert is a politician. If Barbara were sad, then Robert is driving a car.
If Robert were an artist, then Barbara is sad can be inferred via the rewriting rule.