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, x is a police officer if and only if x will play squash. For all x, x is not a police officer. For all x, x will play squash if and only if x is a police officer.
For all x, if x were a police officer, then x is playing squash can be inferred via the universal biconditional elimination rule. For all x, if x plays squash, then x is a police officer can be inferred via the universal biconditional elimination rule. For all x, if x plays squash, then x is a police officer can be inferred via the universal biconditional elimination rule. For all x, if x were a police officer, then x is playing squash can be inferred via the universal biconditional elimination rule. For all x, x will not play squash can be inferred via the universal biconditional elimination rule. For all x, x will not play squash can be inferred via the universal biconditional elimination rule.