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 will play tennis if and only if x_6 is a mechanic. For all x_6, x_6 is excited or x_6 is not a mechanic.
For all x_6, if x_6 were a mechanic, then x_6 is excited can be inferred via the universal rewriting rule. For all x_6, if x_6 plays tennis, then x_6 is a mechanic can be inferred via the universal biconditional elimination rule. For all x_6, if x_6 were a mechanic, then x_6 is playing tennis can be inferred via the universal biconditional elimination rule.