Parts Unknown: Mereologies for Solid Physical Objects

When describing a mereological relationship, the use of the word “part” to whole hides the intended semantics of the parthood relations. Existing studies in mereology usually present part of as a general top level mereology relation, and all other mereological relations are sub-relations under it. We present an alternative approach of mereological pluralism, in which each mereological relation corresponds to one characteristic of the solid physical object, and the characteristics are formalized in different modules within an upper ontology. A general suite of upper ontology modules is proposed in this paper to support the specification of the parthood relations for solid physical objects. We name the union of these modules Ontology of Solid Physical Objects (OPO).