How to Answer Queries over Web Services that return Incomplete Answers

The talk deals with how to answer a query over web services.The services expose access methods that may require input arguments. Users interact with the data by posing declarative queries written on the underlying relations, and the goal is to translate these queries into a procedural plan that issues calls to the services. An additional challenge is that some of the services may have a bound on the number of answers they return, and thus will return only a (non-deterministic) subset of the answers. In performing the translation, we will need to make use of background knowledge about the semantics of data, given as a collection of sentences in logic.

The focus of the talk is the theory of implementing queries over non-deterministic APIs, which connects to a number of issues in logic, particularly Craig interpolation and the analysis of guarded logics. This is joint work with Antoine Amarilli.