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: Susan is not an office clerk. James is not reading a book. Robert is sleeping if and only if Susan is an office clerk. If Susan cooks, then Mary is not climbing a mountain. If it is late, then James is reading a book. Robert is sleeping or Mary is climbing a mountain.
It is not late can be inferred via the modus tollens rule. Susan is not an office clerk and James is not reading a book can be inferred via the conjunction rule. James is not reading a book and Susan is not an office clerk can be inferred via the conjunction rule. If Robert sleeps, then Susan is an office clerk can be inferred via the biconditional elimination rule. If Susan were an office clerk, then Robert is sleeping can be inferred via the biconditional elimination rule. Robert is not sleeping can be inferred via the biconditional elimination rule.