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: It is overcast if and only if it is cold. If William plays tennis, then it is overcast. Charles is not a sailor. If it is cold, then Charles is a sailor.
It is not cold can be inferred via the modus tollens rule. If it is overcast, then it is cold can be inferred via the biconditional elimination rule. If it is cold, then it is overcast can be inferred via the biconditional elimination rule.