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 is a soldier or x_6 will climb a mountain. For all x_6, x_6 is fast or x_6 is not an artist. There is at least one x_6 for which if x_6 were a soldier, then x_6 is fast. For all x_6, if x_6 climbs a mountain, then x_6 is an artist.
For all x_6, if x_6 were an artist, then x_6 is fast can be inferred via the universal rewriting rule.