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: James is playing squash if and only if David is playing tennis. For all x, x is not a bartender. For all x, if x plays tennis, then x is a bartender.
If James plays squash, then David is playing tennis can be inferred via the biconditional elimination rule. If David plays tennis, then James is playing squash can be inferred via the biconditional elimination rule. For all x, x will not play tennis can be inferred via the universal modus tollens rule.