What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Name the inference rule being used: If John drinks water, then John is a nurse. Mary is not sleeping. It is late or John is drinking water. Mary is sleeping if and only if it is late.
If Mary sleeps, then it is late can be inferred via the biconditional elimination rule. If it is late, then Mary is sleeping can be inferred via the biconditional elimination rule. It is not late can be inferred via the biconditional elimination rule.