What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Barbara is not a mechanic. For all y_2, y_2 is a mechanic if and only if y_2 is an office clerk.
For all y_2, if y_2 were a mechanic, then y_2 is an office clerk. For all y_2, if y_2 were an office clerk, then y_2 is a mechanic.