This document discusses BestMap, an approach for mapping between SKOS vocabularies that takes an extensional view. BestMap models mappings as OWL classes that classify resources annotated using one vocabulary and infer annotations using the other vocabulary. It allows for many-to-many mappings between concepts and integrates with SKOS by connecting concepts to resources. BestMap provides a flexible and reusable way to map between vocabularies while remaining compatible with SKOS semantics.