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: If David plays a game, then it is late. It is not raining. If Mary cooks, then David is playing a game. It is raining if and only if it is late.
If it rains, then it is late can be inferred via the biconditional elimination rule. If it is late, then it is raining can be inferred via the biconditional elimination rule. It is not late can be inferred via the biconditional elimination rule.