What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? David is poor or Barbara is not reading a book. For all x_13, if x_13 were poor, then x_13 is an astronaut. For all x_13, if x_13 were an astronaut, then x_13 is poor.
If Barbara reads a book, then David is poor. For all x_13, x_13 is poor if and only if x_13 is an astronaut. For all x_13, x_13 is an astronaut if and only if x_13 is poor.