What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? There is at least one z for which z is bored if and only if z is a mechanic. For all z, z is not bored.
There is at least one z for which if z were bored, then z is a mechanic. There is at least one z for which if z were a mechanic, then z is bored. There is at least one z for which z is not a mechanic.