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: William is a politician or Robert is not sleeping. It is sunny if and only if it is windy. William is not a politician. If Robert doesn't sleep, then it is sunny.
Robert is not sleeping can be inferred via the disjunctive syllogism rule. If Robert sleeps, then William is a politician can be inferred via the rewriting rule. If it is sunny, then it is windy can be inferred via the biconditional elimination rule. If it is windy, then it is sunny can be inferred via the biconditional elimination rule.