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_2, x_2 is a sailor or x_2 is fast. For all x_2, x_2 is fast if and only if x_2 is a carpenter. For all x_2, x_2 is not a sailor.
For all x_2, x_2 is fast can be inferred via the universal disjunctive syllogism rule. For all x_2, if x_2 were fast, then x_2 is a carpenter can be inferred via the universal biconditional elimination rule. For all x_2, if x_2 were a carpenter, then x_2 is fast can be inferred via the universal biconditional elimination rule.