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, if x_9 were an artist, then x_9 is a soldier. For all x_9, if x_9 were a soldier, then x_9 is a musician. For all x_9, x_9 will not play tennis. There is at least one x_9 for which x_9 will play tennis if and only if x_9 is a musician.
For all x_9, if x_9 were an artist, then x_9 is a musician can be inferred via the universal transitivity rule. There is at least one x_9 for which if x_9 plays tennis, then x_9 is a musician can be inferred via the existential biconditional elimination rule. There is at least one x_9 for which if x_9 were a musician, then x_9 is playing tennis can be inferred via the existential biconditional elimination rule. There is at least one x_9 for which x_9 is not a musician can be inferred via the existential biconditional elimination rule.