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, if x_6 were an electrician, then x_6 is sleeping. For all x_6, if x_6 sleeps, then x_6 is a sailor. For all x_6, if x_6 were an astronaut, then x_6 is an electrician. There is at least one x_6 for which if x_6 were a sailor, then x_6 is an astronaut.
For all x_6, if x_6 were an electrician, then x_6 is a sailor can be inferred via the universal transitivity rule. For all x_6, if x_6 were an astronaut, then x_6 is sleeping can be inferred via the universal transitivity rule. There is at least one x_6 for which if x_6 were a sailor, then x_6 is an electrician can be inferred via the existential transitivity rule. There is at least one x_6 for which if x_6 sleeps, then x_6 is an astronaut can be inferred via the existential transitivity rule.