Consider the following premises. For all z_4, z_4 will drink water or z_4 is not an artist. For all z_4, if z_4 were a scientist, then z_4 is an artist. For all z_4, z_4 is a scientist if and only if z_4 will drink water. Can we infer the following from them? For all z_4, z_4 will drink water if and only if z_4 is a scientist.
 From the fact that for all z_4, z_4 will drink water or z_4 is not an artist we can infer that for all z_4, if z_4 were an artist, then z_4 is drinking water. From the fact that for all z_4, if z_4 were a scientist, then z_4 is an artist, and that for all z_4, if z_4 were an artist, then z_4 is drinking water we can infer that for all z_4, if z_4 were a scientist, then z_4 is drinking water. From the fact that for all z_4, z_4 is a scientist if and only if z_4 will drink water we can infer that for all z_4, if z_4 drinks water, then z_4 is a scientist. Finally, from the fact that for all z_4, if z_4 drinks water, then z_4 is a scientist, and that for all z_4, if z_4 were a scientist, then z_4 is drinking water we can infer that for all z_4, z_4 will drink water if and only if z_4 is a scientist. Therefore, the answer is yes.