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 climbs a mountain, then y is a police officer. For all y, y is a police officer if and only if y is sad. There is at least one y for which if y plays squash, then y is a police officer. For all y, y is sad or y will play squash. For all y, if y were sad, then y is climbing a mountain.
For all y, if y were sad, then y is a police officer. For all y, if y were a police officer, then y is sad. For all y, if y were sad, then y is a police officer.