What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? It is sunny if and only if Richard is making tea. It is not sunny. Linda is sad. Richard is making tea or it is overcast.
It is not sunny and Linda is sad. Linda is sad and it is not sunny. If it is sunny, then Richard is making tea. If Richard makes tea, then it is sunny. Richard is not making tea.