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: Joseph is a mechanic or John is making tea. If Joseph were a mechanic, then Karen is working. If Richard were a nurse, then Karen is not working. If it is cloudy, then Karen is working. If John makes tea, then it is cloudy. If Karen works, then it is cloudy.
If Joseph were a mechanic, then it is cloudy can be inferred via the transitivity rule. If John makes tea, then Karen is working can be inferred via the transitivity rule. It is cloudy if and only if Karen is working can be inferred via the biconditional introduction rule. Karen is working if and only if it is cloudy can be inferred via the biconditional introduction rule.