What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? If it is cold, then Robert is sleeping. If Richard were a cashier, then Barbara is working. If Robert sleeps, then Michael is writing a letter. Richard is a cashier or it is cold. Michael is writing a letter or Barbara is not working.
If it is cold, then Michael is writing a letter. If Barbara works, then Michael is writing a letter.