Consider the following premises. For all x_26, if x_26 were a scientist, then x_26 is fast. It is overcast and Barbara is climbing a mountain. For all x_26, if x_26 were fast, then x_26 is sad. For all x_26, if x_26 drinks water, then x_26 is fast. For all x_26, x_26 will drink water or x_26 is a scientist. Can we infer the following from them? If we can, name the inference rule being used: It is not overcast.
 From the fact that for all x_26, if x_26 drinks water, then x_26 is fast, that for all x_26, if x_26 were a scientist, then x_26 is fast, and that for all x_26, x_26 will drink water or x_26 is a scientist we can infer that for all x_26, x_26 is fast via universal disjunction elimination. Finally, from the fact that it is overcast and Barbara is climbing a mountain we can infer that it is overcast via simplification, which contradicts that It is not overcast. Therefore, the answer is no.