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 not overcast. It is windy if and only if it is overcast. Robert is working if and only if it is windy. If it is windy, then it is overcast.
It is not windy can be inferred via the modus tollens rule. If it is windy, then it is overcast can be inferred via the biconditional elimination rule. If Robert works, then it is windy can be inferred via the biconditional elimination rule. If it is overcast, then it is windy can be inferred via the biconditional elimination rule. If it is windy, then Robert is working can be inferred via the biconditional elimination rule. It is not windy can be inferred via the biconditional elimination rule.