What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? David is reading a book or it is late. James is an astronaut if and only if it is late. Patricia is not drinking water. If David reads a book, then Patricia is drinking water.
David is not reading a book. If James were an astronaut, then it is late. If it is late, then James is an astronaut.