Sasa Buvac and John McCarthy
It is often necessary to combine objects that were not designed to work together. These objects may be databases of facts, programs, hardware or plans. Even if the objects were intended to be used together, maintenaince of adherence to their specifications and ensuring the consistency of terminology through time is often difficult. Each object was developed in a context, and these contexts differ, either slightly or greatly. The terminology within each subcontext is likely to be specialized, and making them work together requires some generalization. We describe an approach based on our formal theory of context, the basic papers about which were written starting in 1993. An umbrella context refers to the subcontexts as first class objects, andd the basic relations are ist(c,p), meaning that the proposition p is true in the context c. and also value(c, e), designating the value of the term e in the context c. Besides these there are lifting formulas that relate the propositions and terms in subcontexts to possibly more general propositions and terms in the outer context. Subcontexts are often specialized with regard to time, place and terminology. The goal is that no matter what corners the specialists paint themselves into, what they do can be lifted out and used in a more general context.