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, x is fast if and only if x is an astronaut. For all x, x is an astronaut.
For all x, if x were fast, then x is an astronaut can be inferred via the universal biconditional elimination rule. For all x, if x were an astronaut, then x is fast can be inferred via the universal biconditional elimination rule.