  We implement Groenendijk and Stokhof's partition semantics of questions in a
simple question answering algorithm. The algorithm is sound, complete, and
based on tableau theorem proving. The algorithm relies on a syntactic
characterization of answerhood: Any answer to a question is equivalent to some
formula built up only from instances of the question. We prove this
characterization by translating the logic of interrogation to classical
predicate logic and applying Craig's interpolation theorem.
