Consider the following premises. For all x_1, x_1 is a taxi driver if and only if x_1 is a sailor. There is at least one x_1 for which x_1 is a taxi driver if and only if x_1 is a carpenter. For all x_1, x_1 is a carpenter or x_1 is a sailor. Can we infer the following from them? There is at least one x_1 for which x_1 is a taxi driver.
 From the fact that for all x_1, x_1 is a taxi driver if and only if x_1 is a sailor we can infer that for all x_1, if x_1 were a sailor, then x_1 is a taxi driver. From the fact that there is at least one x_1 for which x_1 is a taxi driver if and only if x_1 is a carpenter we can infer that there is at least one x_1 for which if x_1 were a carpenter, then x_1 is a taxi driver. Finally, from the fact that there is at least one x_1 for which if x_1 were a carpenter, then x_1 is a taxi driver, that for all x_1, if x_1 were a sailor, then x_1 is a taxi driver, and that for all x_1, x_1 is a carpenter or x_1 is a sailor we can infer that there is at least one x_1 for which x_1 is a taxi driver. Therefore, the answer is yes.