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: For all y, if y plays squash, then y is climbing a mountain. Michael is playing squash or William is working. Michael is not climbing a mountain. For all y, if y climbs a mountain, then y is playing squash.
For all y, y will play squash if and only if y will climb a mountain can be inferred via the universal biconditional introduction rule. For all y, y will climb a mountain if and only if y will play squash can be inferred via the universal biconditional introduction rule.