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: If Richard were an office clerk, then Barbara is fast. Richard is an office clerk if and only if Barbara is fast. Barbara is fast.
If Richard were an office clerk, then Barbara is fast can be inferred via the biconditional elimination rule. If Barbara were fast, then Richard is an office clerk can be inferred via the biconditional elimination rule.