What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all x_13, if x_13 drinks water, then x_13 is reading a book. For all x_13, if x_13 reads a book, then x_13 is drinking water. Charles is reading a book or Richard is not a janitor.
If Richard were a janitor, then Charles is reading a book. For all x_13, x_13 will drink water if and only if x_13 will read a book. For all x_13, x_13 will read a book if and only if x_13 will drink water.