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_6, x_6 will not take a plane. For all x_6, if x_6 were happy, then x_6 is a sailor. For all x_6, if x_6 were a sailor, then x_6 is taking a plane. For all x_6, x_6 is happy or x_6 is not a sailor.
For all x_6, x_6 is not a sailor can be inferred via the universal modus tollens rule. For all x_6, if x_6 were happy, then x_6 is taking a plane can be inferred via the universal transitivity rule. For all x_6, if x_6 were a sailor, then x_6 is happy can be inferred via the universal rewriting rule.