Centre for Intelligent Systems and their ApplicationsBoth semantic web applications and individuals are in need of knowledge infrastructures that can be used in dynamic and distributed environments where autonomous entities create knowledge and build their own view of a domain. The prevailing view today is that the process of ontology evolution is difficult to monitor and control, so few efforts have been made to support such a controlled process formally involving several ontologies. The new paradigm we propose is to use an infrastructure mechanism that processes ontology change proposals from autonomous entities while maintaining user-defined consistency between the ontologies of these entities. This makes so called semantic autonomy possible. A core invention of our approach is to formalise consistency constraints as so called spheres of consistency that define 1) knowledge regions within which consistency is maintained and 2) a variable degree of proof-bounded consistency within these regions. Our infrastructure formalism defines a protocol and its computational semantics, as well as a model theory and proof theory for the reasoning layer of the mechanism. The conclusion of this thesis is that this new paradigm is possible and beneficial, assuming that the knowledge representation is kept simple, the ontology evolution operations are kept simple and one proposal is processed at a tim
