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 it is overcast, then Elisabeth is running. For all z, z is not rich. John is rich if and only if Elisabeth is running.
If John were rich, then Elisabeth is running can be inferred via the biconditional elimination rule. If Elisabeth goes running, then John is rich can be inferred via the biconditional elimination rule.