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, if x_8 climbs a mountain, then x_8 is a soldier. For all x_8, if x_8 were a soldier, then x_8 is climbing a mountain. Elisabeth is a soldier if and only if Thomas is playing tennis. Thomas is not playing tennis.
If Elisabeth were a soldier, then Thomas is playing tennis can be inferred via the biconditional elimination rule. If Thomas plays tennis, then Elisabeth is a soldier can be inferred via the biconditional elimination rule. Elisabeth is not a soldier can be inferred via the biconditional elimination rule. For all x_8, x_8 will climb a mountain if and only if x_8 is a soldier can be inferred via the universal biconditional introduction rule. For all x_8, x_8 is a soldier if and only if x_8 will climb a mountain can be inferred via the universal biconditional introduction rule.