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: p_6 -> q_6. ~s_1. q_6 -> p_6. s_1 <-> q_6.
p_6 <-> q_6 can be inferred via the biconditional introduction rule. q_6 <-> p_6 can be inferred via the biconditional introduction rule. s_1 -> q_6 can be inferred via the biconditional elimination rule. q_6 -> s_1 can be inferred via the biconditional elimination rule. ~q_6 can be inferred via the biconditional elimination rule.