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_9, x_9 is curious or x_9 will make tea. There is at least one x_9 for which x_9 is happy if and only if x_9 will make tea. For all x_9, x_9 is not curious.
For all x_9, x_9 will make tea can be inferred via the universal disjunctive syllogism rule. There is at least one x_9 for which if x_9 were happy, then x_9 is making tea can be inferred via the existential biconditional elimination rule. There is at least one x_9 for which if x_9 makes tea, then x_9 is happy can be inferred via the existential biconditional elimination rule.