Consider the following premises. For all x_6, if x_6 plays a game, then x_6 is drinking water. Elisabeth is not playing a game. For all x_6, x_6 will drink water if and only if x_6 will play a game. Can we infer the following from them? Elisabeth is not drinking water.
 From the fact that for all x_6, x_6 will drink water if and only if x_6 will play a game we can infer that for all x_6, if x_6 drinks water, then x_6 is playing a game. From the fact that for all x_6, if x_6 drinks water, then x_6 is playing a game, and that for all x_6, if x_6 plays a game, then x_6 is drinking water we can infer that for all x_6, x_6 will drink water if and only if x_6 will play a game. From the fact that for all x_6, x_6 will drink water if and only if x_6 will play a game we can infer that Elisabeth is drinking water if and only if Elisabeth is playing a game. Finally, from the fact that Elisabeth is drinking water if and only if Elisabeth is playing a game, and that Elisabeth is not playing a game we can infer that Elisabeth is not drinking water. Therefore, the answer is yes.