What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? John is an artist if and only if it is sunny. Robert is not climbing a mountain. If it is late, then Robert is climbing a mountain. If it is sunny, then it is late.
It is not late. If it is sunny, then Robert is climbing a mountain. If John were an artist, then it is sunny. If it is sunny, then John is an artist.