What can we learn from Ontologists
when constructing UBL?  [2]
• Theory of formal distinctions & connections about
entities, relations, categories
• Properties: identity, rigidity, unity; what changes, what
remains same?
• Part-whole relations: mereotopology, aggregation,
mass/count (plurality)
• Levels: physical, functional, biological, intentional,
social
• Taxonomic constraints
• Property analysis: legal agent, group, social entity,
organization