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_5, x_5 will take a plane or x_5 is a doctor. For all x_5, x_5 will not make tea. There is at least one x_5 for which x_5 will make tea if and only if x_5 will take a plane.
There is at least one x_5 for which if x_5 makes tea, then x_5 is taking a plane can be inferred via the existential biconditional elimination rule. There is at least one x_5 for which if x_5 takes a plane, then x_5 is making tea can be inferred via the existential biconditional elimination rule. There is at least one x_5 for which x_5 will not take a plane can be inferred via the existential biconditional elimination rule.