What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? If Thomas were sad, then John is reading a book. Thomas is not sad. If Thomas were sad, then John is reading a book. If John reads a book, then Thomas is sad.
John is not reading a book. Thomas is sad if and only if John is reading a book. Thomas is sad if and only if John is reading a book. John is reading a book if and only if Thomas is sad. John is reading a book if and only if Thomas is sad.