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_9 for which if x_9 goes running, then x_9 is playing squash. For all x_9, x_9 will not go running. For all x_9, x_9 will play squash if and only if x_9 is a doctor. For all x_9, if x_9 plays squash, then x_9 is running.
For all x_9, x_9 will not play squash can be inferred via the universal modus tollens rule. There is at least one x_9 for which x_9 will go running if and only if x_9 will play squash can be inferred via the existential biconditional introduction rule. There is at least one x_9 for which x_9 will play squash if and only if x_9 will go running can be inferred via the existential biconditional introduction rule. For all x_9, if x_9 plays squash, then x_9 is a doctor can be inferred via the universal biconditional elimination rule. For all x_9, if x_9 were a doctor, then x_9 is playing squash can be inferred via the universal biconditional elimination rule.