What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Name the inference rule being used: There is at least one x_5 for which if x_5 were a taxi driver, then x_5 is a server. For all x_5, if x_5 were a server, then x_5 is a writer. For all x_5, x_5 is a soldier if and only if x_5 is a writer.
There is at least one x_5 for which if x_5 were a taxi driver, then x_5 is a writer can be inferred via the existential transitivity rule. For all x_5, if x_5 were a soldier, then x_5 is a writer can be inferred via the universal biconditional elimination rule. For all x_5, if x_5 were a writer, then x_5 is a soldier can be inferred via the universal biconditional elimination rule.