eyeprolog

RDF 1.2 annotations

Who said this, and when?

Alice’s name is recorded as “Alice”, and the same statement is annotated with who stated it and when it was recorded. EyeProlog recovers the statement together with its annotations, as one auditable claim.

Run it in the playground · Source

The question

Which asserted statements carry provenance, and what is it?

This is one of a family of RDF 1.2 examples. RDF data arrives as rdf(Subject, Predicate, Object, Graph) facts, as produced by rdf-prolog-interchange, and results are printed in the same shape.

The data

rdf(iri('https://example.org/alice'), iri('https://example.org/name'), literal('Alice', datatype('http://www.w3.org/2001/XMLSchema#string')), default_graph).
rdf(iri('https://example.org/claim1'), iri('http://www.w3.org/1999/02/22-rdf-syntax-ns#reifies'), triple(iri('https://example.org/alice'), iri('https://example.org/name'), literal('Alice', datatype('http://www.w3.org/2001/XMLSchema#string'))), default_graph).
rdf(iri('https://example.org/claim1'), iri('https://example.org/statedBy'), iri('https://example.org/carol'), default_graph).
rdf(iri('https://example.org/claim1'), iri('https://example.org/recorded'), literal('2025-01-15', datatype('http://www.w3.org/2001/XMLSchema#date')), default_graph).

An RDF 1.2 annotation asserts a triple and also describes it. A reifier (claim1) stands for the statement through rdf:reifies, and ordinary triples about the reifier carry the metadata: Carol stated it, on 15 January 2025.

The rule

annotated_claim(S, P, O, Reifier, Source, Date) :-
  rdf(S, P, O, default_graph),
  rdf(
    Reifier,
    iri('http://www.w3.org/1999/02/22-rdf-syntax-ns#reifies'),
    triple(S, P, O),
    default_graph
  ),
  rdf(
    Reifier,
    iri('https://example.org/statedBy'),
    Source,
    default_graph
  ),
  rdf(
    Reifier,
    iri('https://example.org/recorded'),
    Date,
    default_graph
  ).

An annotated claim needs four things to line up: the asserted triple, a reifier that points to that very triple, a source, and a date. The shared variables S, P, O and Reifier do the joining.

The answer

eyeprolog examples/rdf12-annotation.pl

result_rdf(iri('https://example.org/alice'), iri('https://example.org/name'), literal('Alice', datatype('http://www.w3.org/2001/XMLSchema#string')), default_graph).
result_rdf(iri('https://example.org/claim1'), iri('http://www.w3.org/1999/02/22-rdf-syntax-ns#reifies'), triple(iri('https://example.org/alice'), iri('https://example.org/name'), literal('Alice', datatype('http://www.w3.org/2001/XMLSchema#string'))), default_graph).
result_rdf(iri('https://example.org/claim1'), iri('https://example.org/statedBy'), iri('https://example.org/carol'), default_graph).
result_rdf(iri('https://example.org/claim1'), iri('https://example.org/recorded'), literal('2025-01-15', datatype('http://www.w3.org/2001/XMLSchema#date')), default_graph).

Four results: the statement and its three annotation triples, written back as RDF.

The reason

step(result_rdf(iri('https://example.org/alice'), iri('https://example.org/name'), literal('Alice', datatype('http://www.w3.org/2001/XMLSchema#string')), default_graph),
     rule(6),
     ['S' = iri('https://example.org/alice'),
      'P' = iri('https://example.org/name'),
      'O' = literal('Alice', datatype('http://www.w3.org/2001/XMLSchema#string'))],
     [annotated_claim(iri('https://example.org/alice'), iri('https://example.org/name'), literal('Alice', datatype('http://www.w3.org/2001/XMLSchema#string')), iri('https://example.org/claim1'), iri('https://example.org/carol'), literal('2025-01-15', datatype('http://www.w3.org/2001/XMLSchema#date')))]).

The statement is re-emitted only because a complete annotated claim was found; the annotated_claim/6 step below it cites all four source triples.

The check

condition('C1', resolution, ok, 9).
condition('C4', coverage, ok, 12).
condition('C7', relevance, ok, 13).
trusted(0).
verdict(checked).

All nine steps replay against the program.

Try it

Delete the recorded triple and predict the output. Is it right that an unannotated statement disappears entirely?
Add a second reifier for the same statement, stated by someone else, and count the results.
See ranking annotated claims for annotations that drive a decision, and the scientific evidence graph for a larger case.

Learn more in The Art of EyeProlog, Chapter 14.

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