In our work we extend the traditional bipartite model of ontologies with the social dimension, leading to a tripartite model
of actors, concepts and instances. We demonstrate the application of this representation by showing how community-based semantics
emerges from this model through a process of graph transformation. We illustrate ontology emergence by two case studies, an
analysis of a large scale folksonomy system and a novel method for the extraction of community-based ontologies from Web pages.