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 z, z is not fast. For all z, if z were fast, then z is a mechanic. For all z, z is a mechanic if and only if z is fast.
For all z, if z were a mechanic, then z is fast can be inferred via the universal biconditional elimination rule. For all z, if z were fast, then z is a mechanic can be inferred via the universal biconditional elimination rule. For all z, z is not a mechanic can be inferred via the universal biconditional elimination rule.