Consider the following premises. For all y, y is not a soldier. Richard is playing squash if and only if Jennifer is climbing a mountain. If Richard plays squash, then David is a soldier. Can we infer the following from them? If we can, name the inference rule being used: Jennifer is not climbing a mountain.
 From the fact that for all y, y is not a soldier we can infer that David is not a soldier via universal instantiation. From the fact that if Richard plays squash, then David is a soldier, and that David is not a soldier we can infer that Richard is not playing squash via modus tollens. Finally, from the fact that Richard is playing squash if and only if Jennifer is climbing a mountain, and that Richard is not playing squash we can infer that Jennifer is not climbing a mountain via biconditional elimination. Therefore, the answer is yes.