  We consider answering queries on data available through access methods, that
provide lookup access to the tuples matching a given binding. Such interfaces
are common on the Web; further, they often have bounds on how many results they
can return, e.g., because of pagination or rate limits. We thus study
result-bounded methods, which may return only a limited number of tuples. We
study how to decide if a query is answerable using result-bounded methods,
i.e., how to compute a plan that returns all answers to the query using the
methods, assuming that the underlying data satisfies some integrity
constraints. We first show how to reduce answerability to a query containment
problem with constraints. Second, we show "schema simplification" theorems
describing when and how result-bounded services can be used. Finally, we use
these theorems to give decidability and complexity results about answerability
for common constraint classes.
