When combining data from distinct sources, there is a need to share
meta-data and other knowledge about various source domains. Due to
semantic inconsistencies, problems arise when combining knowledge
across domains when the knowledge is simply merged.   Also, knowledge
that is irrelevant to the task of interoperation  will be included,
making the result unnecessarily complex.  An algebra over
domain ontologies has been proposed to  support disciplined
manipulation among heterogeneous systems. 
This  paper describes the domain ontology algebra and the use of 
articulation rules to link  declarative interfaces. In particular, it
discusses the articulation's implementation as part of CLIPS production
system capable of operating over the ontologies described by the
interfaces of objects registered in multiple CORBA servers.