What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? If Mary were an artist, then Mary is an electrician. Mary is not an electrician. Mary is an artist or Mary is not an electrician. Barbara is poor if and only if Mary is an artist.
Mary is not an artist. If Mary were an electrician, then Mary is an artist. If Barbara were poor, then Mary is an artist. If Mary were an artist, then Barbara is poor.