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, y_2 is rich if and only if y_2 is a mechanic. For all y_2, y_2 is rich if and only if y_2 is sad.
For all y_2, if y_2 were rich, then y_2 is a mechanic can be inferred via the universal biconditional elimination rule. For all y_2, if y_2 were rich, then y_2 is sad can be inferred via the universal biconditional elimination rule. For all y_2, if y_2 were a mechanic, then y_2 is rich can be inferred via the universal biconditional elimination rule. For all y_2, if y_2 were sad, then y_2 is rich can be inferred via the universal biconditional elimination rule.