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 y_1, if y_1 were a soldier, then y_1 is running. For all y_1, y_1 is a sailor. For all y_1, y_1 will go running if and only if y_1 is a soldier. For all y_1, if y_1 were a soldier, then y_1 is not a sailor.
For all y_1, y_1 is not a soldier can be inferred via the universal modus tollens rule. For all y_1, if y_1 goes running, then y_1 is a soldier can be inferred via the universal biconditional elimination rule. For all y_1, if y_1 were a soldier, then y_1 is running can be inferred via the universal biconditional elimination rule.