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_8, x_8 is not a carpenter. For all x_8, x_8 will take a plane. For all x_8, x_8 will climb a mountain if and only if x_8 is a carpenter. For all x_8, x_8 will climb a mountain or x_8 will play tennis.
For all x_8, if x_8 climbs a mountain, then x_8 is a carpenter can be inferred via the universal biconditional elimination rule. For all x_8, if x_8 were a carpenter, then x_8 is climbing a mountain can be inferred via the universal biconditional elimination rule. For all x_8, x_8 will not climb a mountain can be inferred via the universal biconditional elimination rule.