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RDF and ontology mappings

From NeoWiki Demo

Every NeoWiki page's Subjects are available as RDF. The same data is offered in two ways:

  • A native projection in NeoWiki's own vocabulary. Lossless, always available, no setup.
  • Ontology projections that re-express the data in an established vocabulary such as the Europeana Data Model (EDM). Each one is defined by a Mapping page.

Each export is produced on demand from the page's current data and downloads as a Turtle or TriG file. A projection can also be kept in a SPARQL store and queried live. This wiki has such a store: see SPARQL queries. The store holds the native and the EDM projection side by side, so a query can join across both — see EDM queries.

The Mapping page

Each Mapping page targets one ontology, named by the page title, and holds an entry for every mapped Schema. Special:Mappings lists them all; this wiki ships two:

  • Mapping:EDM: the Person, City, Place, Artwork and Artist Schemas mapped to EDM; the Birth Schema, deliberately given no EDM class, instead contributes flat triples to the people it points at
  • Mapping:CIDOC-CRM: the same Schemas mapped to CIDOC CRM, which routes birth and production through event nodes that NeoWiki's data does not hold and the Mapping synthesizes

Explore the projections

Follow these in order; each link downloads the projection so you can read it.

You don't need these links to reach an export: on any subject page, the Data tab offers per-projection downloads (Turtle or TriG) and a copy-IRI control, and the sidebar has a View RDF link.

  1. Pablo Picasso, native vs EDM: the native file has everything, including the two-layer "Born in" relation and the page metadata; the EDM file is an edm:Agent carrying only the mapped vocabulary, with the unmapped Source absent.
  2. Málaga, EDM: an edm:Place with the very same entity IRI that Picasso's rdaGr2:placeOfBirth points at, because sibling projections share entity IRIs.
  3. The Milkmaid, EDM: an edm:ProvidedCHO whose dc:creator is the IRI of Vermeer (an edm:Agent) and whose edm:currentLocation is the Rijksmuseum.
  4. Johann Sebastian Bach, EDM: Bach's birth is modelled as its own Birth Subject instead of flat fields. The EDM Mapping collapses it back to flat rdaGr2:dateOfBirth and rdaGr2:placeOfBirth, but the Birth page emits those triples, so this page's export does not show them — a store or bulk dump holding both graphs does.
  5. Pablo Picasso, CIDOC CRM: the same flat birth fields go the other way. CIDOC routes birth through an E67_Birth event and an E52_Time-Span, neither of which exists in the data, so the Mapping synthesizes both and hangs the date and the place off them.
  6. ACME Inc, EDM: its Company Schema has no EDM Mapping, so the EDM projection comes back empty. An unmapped Schema is simply left out, so the projection stays conformant.

Learn more

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