What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? John is drinking water. Michael is running if and only if it is cloudy. Charles is writing a letter if and only if it is cloudy. Charles is not writing a letter.
John is drinking water and Charles is not writing a letter. Charles is not writing a letter and John is drinking water. If Michael goes running, then it is cloudy. If Charles writes a letter, then it is cloudy. If it is cloudy, then Michael is running. If it is cloudy, then Charles is writing a letter. It is not cloudy.