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, if x_2 were poor, then x_2 is bored. For all x_2, if x_2 were bored, then x_2 is a mechanic. For all x_2, if x_2 were a mechanic, then x_2 is bored. There is at least one x_2 for which x_2 is a server or x_2 is not a mechanic.
For all x_2, if x_2 were poor, then x_2 is a mechanic can be inferred via the universal transitivity rule. There is at least one x_2 for which if x_2 were a mechanic, then x_2 is a server can be inferred via the existential rewriting rule. For all x_2, x_2 is bored if and only if x_2 is a mechanic can be inferred via the universal biconditional introduction rule. For all x_2, x_2 is a mechanic if and only if x_2 is bored can be inferred via the universal biconditional introduction rule.