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, if x works, then x is fast. For all x, x will work or x will not climb a mountain. For all x, if x were fast, then x is working. For all x, if x were a musician, then x is climbing a mountain.
For all x, if x climbs a mountain, then x is working can be inferred via the universal rewriting rule. For all x, x will work if and only if x is fast can be inferred via the universal biconditional introduction rule. For all x, x is fast if and only if x will work can be inferred via the universal biconditional introduction rule.