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 writes a letter, then x_6 is taking a plane. There is at least one x_6 for which if x_6 cooks, then x_6 is an astronaut. For all x_6, x_6 is an electrician or x_6 will write a letter. For all x_6, x_6 is not an electrician or x_6 will cook. For all x_6, if x_6 takes a plane, then x_6 is an astronaut.
For all x_6, if x_6 writes a letter, then x_6 is an astronaut can be inferred via the universal transitivity rule. For all x_6, x_6 will write a letter or x_6 will cook can be inferred via the universal resolution rule.