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: For all x, if x makes tea, then x is a taxi driver. For all x, if x were bored, then x is making tea. There is at least one x for which x is a sailor if and only if x is a taxi driver.
For all x, if x were bored, then x is a taxi driver can be inferred via the universal transitivity rule. There is at least one x for which if x were a sailor, then x is a taxi driver can be inferred via the existential biconditional elimination rule. There is at least one x for which if x were a taxi driver, then x is a sailor can be inferred via the existential biconditional elimination rule.