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_4, x_4 will take a plane. There is at least one x_4 for which if x_4 climbs a mountain, then x_4 is playing squash. For all x_4, x_4 will climb a mountain.
There is at least one x_4 for which x_4 will play squash can be inferred via the existential modus ponens rule. For all x_4, x_4 will take a plane and x_4 will climb a mountain can be inferred via the universal conjunction rule. For all x_4, x_4 will climb a mountain and x_4 will take a plane can be inferred via the universal conjunction rule.