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: If Elisabeth were an astronaut, then John is making tea. If John makes tea, then Elisabeth is an astronaut. If John makes tea, then Elisabeth is an astronaut.
Elisabeth is an astronaut if and only if John is making tea can be inferred via the biconditional introduction rule. Elisabeth is an astronaut if and only if John is making tea can be inferred via the biconditional introduction rule. John is making tea if and only if Elisabeth is an astronaut can be inferred via the biconditional introduction rule. John is making tea if and only if Elisabeth is an astronaut can be inferred via the biconditional introduction rule.