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