Queries

For each required function of the interface, we should define a specific query. The query consists of three parts. The first is the predicate name, which obviously should have a relation to the intended function. The second part consists of the input arguments, which are used to pass information from the outside to the problem solver. The structure of these arguments should be as simple as possible, easy to generate and to analyze. The third part consists of the output arguments, which are used to pass information from the problem solver back to the calling interface. When calling the query these arguments will be free variables, which are instantiated inside the solver to some result data structure. The critical issue in defining the queries lies in identifying which data are required and/or produced, without building an actual implementation of the system. Another issue is the format of the data, which should allow a simple and efficient implementation without extra overhead for data manipulation. It is most important to get this interface right from the start, as any change will create re-work and problems integrating different versions of the software.