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_2, if y_2 were curious, then y_2 is bored. For all y_2, if y_2 were bored, then y_2 is curious. For all y_2, if y_2 were bored, then y_2 is curious.
For all y_2, y_2 is curious if and only if y_2 is bored can be inferred via the universal biconditional introduction rule. For all y_2, y_2 is curious if and only if y_2 is bored can be inferred via the universal biconditional introduction rule. For all y_2, y_2 is bored if and only if y_2 is curious can be inferred via the universal biconditional introduction rule. For all y_2, y_2 is bored if and only if y_2 is curious can be inferred via the universal biconditional introduction rule.