What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? David is running if and only if it is late. It is cloudy if and only if Susan is a bartender. Susan is not a bartender. David is not running.
Susan is not a bartender and David is not running. David is not running and Susan is not a bartender. If David goes running, then it is late. If it is cloudy, then Susan is a bartender. If it is late, then David is running. If Susan were a bartender, then it is cloudy. It is not late. It is not cloudy.