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_19 for which x_19 will play tennis if and only if x_19 is sad. For all x_19, x_19 will not cook or x_19 will go running. For all x_19, x_19 is not sad. For all x_19, x_19 will cook or x_19 will play tennis. For all x_19, x_19 will make tea.
For all x_19, x_19 will play tennis or x_19 will go running can be inferred via the universal resolution rule. There is at least one x_19 for which if x_19 plays tennis, then x_19 is sad can be inferred via the existential biconditional elimination rule. There is at least one x_19 for which if x_19 were sad, then x_19 is playing tennis can be inferred via the existential biconditional elimination rule. There is at least one x_19 for which x_19 will not play tennis can be inferred via the existential biconditional elimination rule.