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 z, if z were a politician, then z is taking a plane. For all z, z is not a politician. For all z, if z takes a plane, then z is a scientist. There is at least one z for which z is a politician or z is not a scientist.
For all z, if z were a politician, then z is a scientist can be inferred via the universal transitivity rule. There is at least one z for which if z were a scientist, then z is a politician can be inferred via the existential rewriting rule.