Consider the following premises. For all x_13, x_13 is a scientist or x_13 is a taxi driver. Mary is a taxi driver if and only if Barbara is running. Mary is a scientist if and only if Barbara is running. Can we infer the following from them? Barbara is not running.
 From the fact that for all x_13, x_13 is a scientist or x_13 is a taxi driver we can infer that Mary is a scientist or Mary is a taxi driver. From the fact that Mary is a scientist if and only if Barbara is running we can infer that if Mary were a scientist, then Barbara is running. From the fact that Mary is a taxi driver if and only if Barbara is running we can infer that if Mary were a taxi driver, then Barbara is running. Finally, from the fact that if Mary were a scientist, then Barbara is running, that if Mary were a taxi driver, then Barbara is running, and that Mary is a scientist or Mary is a taxi driver we can infer that Barbara is running, which contradicts that Barbara is not running. Therefore, the answer is no.