What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Barbara is a bartender if and only if it is late. For all x, x will not sleep. Barbara is a bartender if and only if Susan is sleeping.
If Barbara were a bartender, then it is late. If Barbara were a bartender, then Susan is sleeping. If it is late, then Barbara is a bartender. If Susan sleeps, then Barbara is a bartender.