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: q_4 or t. ~s_1. s_1 <-> q_4.
s_1 -> q_4 can be inferred via the biconditional elimination rule. q_4 -> s_1 can be inferred via the biconditional elimination rule. ~q_4 can be inferred via the biconditional elimination rule.