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 Barbara plays tennis, then it is snowing. If Jessica makes tea, then Barbara is playing tennis. If it is not overcast, then Jessica is making tea. John is not running. John is running if and only if it is overcast.
If Jessica makes tea, then it is snowing can be inferred via the transitivity rule. If it is not overcast, then Barbara is playing tennis can be inferred via the transitivity rule. If John goes running, then it is overcast can be inferred via the biconditional elimination rule. If it is overcast, then John is running can be inferred via the biconditional elimination rule. It is not overcast can be inferred via the biconditional elimination rule.