Consider the following premises. For all x_12, x_12 is a carpenter if and only if x_12 is an office clerk. For all z_1, z_1 is not a bartender. Linda is a bartender if and only if Robert is an office clerk. Can we infer the following from them? If we can, name the inference rule being used: Robert is a carpenter.
 From the fact that for all x_12, x_12 is a carpenter if and only if x_12 is an office clerk we can infer that Robert is a carpenter if and only if Robert is an office clerk via universal instantiation. From the fact that for all z_1, z_1 is not a bartender we can infer that Linda is not a bartender via universal instantiation. From the fact that Linda is a bartender if and only if Robert is an office clerk, and that Linda is not a bartender we can infer that Robert is not an office clerk via biconditional elimination. Finally, from the fact that Robert is a carpenter if and only if Robert is an office clerk, and that Robert is not an office clerk we can infer that Robert is not a carpenter via biconditional elimination, which contradicts that Robert is a carpenter. Therefore, the answer is no.