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 reads a book, then x is driving a car. There is at least one x for which if x climbs a mountain, then x is reading a book. For all x, x is fast if and only if x will climb a mountain.
There is at least one x for which if x climbs a mountain, then x is driving a car can be inferred via the existential transitivity rule. For all x, if x were fast, then x is climbing a mountain can be inferred via the universal biconditional elimination rule. For all x, if x climbs a mountain, then x is fast can be inferred via the universal biconditional elimination rule.