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: Charles is not playing a game. If Charles plays a game, then William is a poet. If Charles plays a game, then William is a poet. If William were a poet, then Charles is playing a game.
William is not a poet can be inferred via the modus tollens rule. Charles is playing a game if and only if William is a poet can be inferred via the biconditional introduction rule. Charles is playing a game if and only if William is a poet can be inferred via the biconditional introduction rule. William is a poet if and only if Charles is playing a game can be inferred via the biconditional introduction rule. William is a poet if and only if Charles is playing a game can be inferred via the biconditional introduction rule.