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 sleeps, then y is making tea. Barbara is sleeping if and only if Barbara is making tea. Barbara is not sleeping.
If Barbara sleeps, then Barbara is making tea can be inferred via the biconditional elimination rule. If Barbara makes tea, then Barbara is sleeping can be inferred via the biconditional elimination rule.