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 tennis. It is raining if and only if Elisabeth is playing a game. If David were a mechanic, then Elisabeth is playing a game. It is raining if and only if Charles is playing tennis.
If it rains, then Elisabeth is playing a game can be inferred via the biconditional elimination rule. If it rains, then Charles is playing tennis can be inferred via the biconditional elimination rule. If Elisabeth plays a game, then it is raining can be inferred via the biconditional elimination rule. If Charles plays tennis, then it is raining can be inferred via the biconditional elimination rule. It is not raining can be inferred via the biconditional elimination rule.