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: Susan is taking a plane if and only if Charles is playing a game. For all y, if y were a poet, then y is playing a game. Susan is not a soldier. Susan is a soldier if and only if Susan is taking a plane.
If Susan takes a plane, then Charles is playing a game can be inferred via the biconditional elimination rule. If Susan were a soldier, then Susan is taking a plane can be inferred via the biconditional elimination rule. If Charles plays a game, then Susan is taking a plane can be inferred via the biconditional elimination rule. If Susan takes a plane, then Susan is a soldier can be inferred via the biconditional elimination rule. Susan is not taking a plane can be inferred via the biconditional elimination rule.