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: Charles is not a mechanic. For all z, z is a mechanic or z is not a bartender. For all z, if z were a mechanic, then z is a bartender.
For all z, if z were a bartender, then z is a mechanic can be inferred via the universal rewriting rule.