What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Robert is a musician if and only if John is writing a letter. It is raining. John is not writing a letter. For all x_17, if x_17 sleeps, then x_17 is a musician. For all x_17, if x_17 were a musician, then x_17 is sleeping.
It is raining and John is not writing a letter. John is not writing a letter and it is raining. If Robert were a musician, then John is writing a letter. If John writes a letter, then Robert is a musician. Robert is not a musician. For all x_17, x_17 will sleep if and only if x_17 is a musician. For all x_17, x_17 is a musician if and only if x_17 will sleep.