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 a sailor. There is at least one x_8 for which if x_8 were a police officer, then x_8 is not playing squash. For all x_8, x_8 will play squash if and only if x_8 is a sailor.
For all x_8, if x_8 plays squash, then x_8 is a sailor can be inferred via the universal biconditional elimination rule. For all x_8, if x_8 were a sailor, then x_8 is playing squash can be inferred via the universal biconditional elimination rule.