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_10, if x_10 were excited, then x_10 is a writer. For all x_10, if x_10 were a writer, then x_10 is a police officer. There is at least one x_10 for which x_10 is not an electrician. For all x_10, x_10 is an electrician if and only if x_10 is a police officer.
For all x_10, if x_10 were excited, then x_10 is a police officer can be inferred via the universal transitivity rule. For all x_10, if x_10 were an electrician, then x_10 is a police officer can be inferred via the universal biconditional elimination rule. For all x_10, if x_10 were a police officer, then x_10 is an electrician can be inferred via the universal biconditional elimination rule. There is at least one x_10 for which x_10 is not a police officer can be inferred via the existential biconditional elimination rule.