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, if x were a police officer, then x is working. For all x, if x works, then x is a police officer. For all x, if x were a police officer, then x is working.
For all x, x is a police officer if and only if x will work can be inferred via the universal biconditional introduction rule. For all x, x will work if and only if x is a police officer can be inferred via the universal biconditional introduction rule. For all x, x will work if and only if x is a police officer can be inferred via the universal biconditional introduction rule. For all x, x is a police officer if and only if x will work can be inferred via the universal biconditional introduction rule.