What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? It is not snowing. Richard is sleeping if and only if Elisabeth is taking a plane. Charles is happy if and only if Michael is excited. Charles is happy if and only if it is snowing. Richard is sleeping if and only if Michael is excited.
If Richard sleeps, then Elisabeth is taking a plane. If Charles were happy, then Michael is excited. If Charles were happy, then it is snowing. If Richard sleeps, then Michael is excited. If Elisabeth takes a plane, then Richard is sleeping. If Michael were excited, then Charles is happy. If it snows, then Charles is happy. If Michael were excited, then Richard is sleeping. Charles is not happy.