What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all y, y is an astronaut if and only if y is a doctor. For all y, if y reads a book, then y is an astronaut. There is at least one y for which y will read a book.
There is at least one y for which y is an astronaut. For all y, if y were an astronaut, then y is a doctor. For all y, if y were a doctor, then y is an astronaut.