What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all y, if y works, then y is climbing a mountain. There is at least one y for which y is not a nurse. For all y, if y climbs a mountain, then y is working. For all y, y will climb a mountain if and only if y is a nurse.
For all y, y will work if and only if y will climb a mountain. For all y, y will climb a mountain if and only if y will work. For all y, if y climbs a mountain, then y is a nurse. For all y, if y were a nurse, then y is climbing a mountain. There is at least one y for which y will not climb a mountain.