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: For all x_15, x_15 is a doctor or x_15 is curious. There is at least one x_15 for which x_15 will play tennis if and only if x_15 will go running. For all x_15, x_15 is not a doctor. For all x_15, if x_15 were a janitor, then x_15 is not curious. For all x_15, x_15 is a janitor or x_15 will go running.
For all x_15, x_15 is curious can be inferred via the universal disjunctive syllogism rule. There is at least one x_15 for which if x_15 plays tennis, then x_15 is running can be inferred via the existential biconditional elimination rule. There is at least one x_15 for which if x_15 goes running, then x_15 is playing tennis can be inferred via the existential biconditional elimination rule.