What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all x_15, x_15 is a mechanic if and only if x_15 will climb a mountain. There is at least one x_15 for which x_15 is not a mechanic. For all x_15, x_15 will climb a mountain or x_15 is a scientist. For all x_15, if x_15 sleeps, then x_15 is not a scientist.
For all x_15, if x_15 were a mechanic, then x_15 is climbing a mountain. For all x_15, if x_15 climbs a mountain, then x_15 is a mechanic. There is at least one x_15 for which x_15 will not climb a mountain.