What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? If Barbara were a bartender, then Mary is a politician. If Mary were a politician, then John is a musician. If it is late, then Barbara is a bartender. If John were a musician, then it is late.
If Barbara were a bartender, then John is a musician. If Mary were a politician, then it is late. If it is late, then Mary is a politician. If John were a musician, then Barbara is a bartender.