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 Sarah cooks, then Sarah is excited. For all x_1, x_1 will cook if and only if x_1 is excited.
For all x_1, if x_1 cooks, then x_1 is excited can be inferred via the universal biconditional elimination rule. For all x_1, if x_1 were excited, then x_1 is cooking can be inferred via the universal biconditional elimination rule.