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, y will sleep if and only if y will climb a mountain. There is at least one y for which y will sleep.
For all y, if y sleeps, then y is climbing a mountain can be inferred via the universal biconditional elimination rule. For all y, if y climbs a mountain, then y is sleeping can be inferred via the universal biconditional elimination rule.