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 a sailor, then x_6 is a scientist. For all x_6, x_6 is a sailor or x_6 will play squash. For all x_6, x_6 is a mechanic or x_6 will not play squash. There is at least one x_6 for which if x_6 were a scientist, then x_6 is a mechanic.
There is at least one x_6 for which if x_6 were a sailor, then x_6 is a mechanic can be inferred via the existential transitivity rule. For all x_6, if x_6 plays squash, then x_6 is a mechanic can be inferred via the universal rewriting rule.