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 y, if y were an astronaut, then y is making tea. There is at least one y for which if y were a politician, then y is making tea. For all y, if y makes tea, then y is an astronaut. For all y, if y were an astronaut, then y is a politician.
For all y, if y makes tea, then y is a politician can be inferred via the universal transitivity rule. There is at least one y for which if y were a politician, then y is an astronaut can be inferred via the existential transitivity rule. There is at least one y for which if y were an astronaut, then y is making tea can be inferred via the existential transitivity rule. For all y, y is an astronaut if and only if y will make tea can be inferred via the universal biconditional introduction rule. For all y, y will make tea if and only if y is an astronaut can be inferred via the universal biconditional introduction rule.