SKOS — When You Don't Need OWL

SKOS is the right answer more often than you think

SKOS (Simple Knowledge Organization System) models concept schemes — thesauri, subject headings, controlled vocabularies — with three core relations:

• skos:broader / skos:narrower — hierarchy
• skos:related — non-hierarchical association
• skos:exactMatch / skos:closeMatch — mappings across schemes

It avoids OWL's subsumption semantics entirely — skos:broader does NOT mean rdfs:subClassOf. That's a feature: it lets you build navigable taxonomies without committing to formal class subsumption you don't actually want.

Rule of thumb: if your domain is terminological (UNESCO subjects, library categories, product taxonomies, medical headings) — start with SKOS. Upgrade to OWL only when you genuinely need DL reasoning.

SKOS is the library card catalogue; OWL is the legal code. Both organise concepts. A card catalogue cheerfully tells you that 'Cookery > French Cookery > Bouillabaisse' — for navigation. It does NOT claim that every French Cookery item is, by formal subsumption, 'a Cookery'; you might want to file a documentary about French cookery under Film instead. A legal code (OWL) DOES claim formal subsumption: if Bouillabaisse ⊑ French Cookery ⊑ Cookery, then every reasoner everywhere will infer the chain. Pick the artefact that matches the commitment you actually want to make.