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: There is at least one x for which x will work if and only if x will go running. For all x, x will work or x is not a cashier. For all x, if x plays tennis, then x is a cashier.
For all x, if x were a cashier, then x is working can be inferred via the universal rewriting rule. There is at least one x for which if x works, then x is running can be inferred via the existential biconditional elimination rule. There is at least one x for which if x goes running, then x is working can be inferred via the existential biconditional elimination rule.