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_11 <-> r_1. ~r. w -> p_11. r_1 -> r. p_11 <-> w.
~r_1 can be inferred via the modus tollens rule. p_11 -> r_1 can be inferred via the biconditional elimination rule. p_11 -> w can be inferred via the biconditional elimination rule. r_1 -> p_11 can be inferred via the biconditional elimination rule. w -> p_11 can be inferred via the biconditional elimination rule.