What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all x_4, x_4 will not climb a mountain. Linda is a cashier if and only if David is a carpenter. For all x_4, x_4 is a carpenter if and only if x_4 will climb a mountain.
If Linda were a cashier, then David is a carpenter. If David were a carpenter, then Linda is a cashier. For all x_4, if x_4 were a carpenter, then x_4 is climbing a mountain. For all x_4, if x_4 climbs a mountain, then x_4 is a carpenter. For all x_4, x_4 is not a carpenter.