vocabulary
Vocabulary normalisation pass for riverbank (v0.15.3 + v0.15.5).
Post-extraction pass that converts the ad-hoc predicate/object vocabulary produced by open-vocabulary extraction into a tighter, semantically consistent schema. The pass is fully domain-agnostic — it operates on the triple buffer and has no knowledge of the subject domain.
Four normalisations are applied in order:
-
Categorical literal promotion — repeated string-valued objects that represent a bounded category (
"Director","Approved","Mammal") are promoted tovocab:*IRI resources. -
Predicate vocabulary collapse — clusters of predicates with a shared semantic root (
ex:is_director/ex:is_ceo/ex:is_chair) are collapsed to a single canonical predicate using either an edit-distance (deterministic) or LLM-guided backend. -
Fact-stuffed predicate decomposition — predicates whose local name embeds a qualifier (year, date, ordinal) are decomposed into a base predicate triple plus a separate qualifier triple.
-
Entity URI canonicalisation — after entity resolution writes
owl:sameAslinks, non-canonical subject URIs are rewritten to the single canonical URI chosen by the resolution pass.
Pipeline position::
extract → entity_resolution → [vocabulary_normalisation] → write
The pass reads from the in-memory triple buffer — no database round-trip is needed.
Profile YAML::
vocabulary_normalisation:
enabled: true
categorical_threshold: 2
collapse_predicates: true
predicate_collapse_backend: "deterministic" # deterministic | llm
decompose_stuffed_predicates: true
rewrite_canonical_uris: false
vocabulary_namespace: "http://riverbank.example/vocab/"
Stats emitted::
vocab_literals_promoted int Literals replaced by vocab:* IRIs
vocab_predicates_collapsed int Predicate rewrites from cluster collapse
vocab_facts_decomposed int Predicates whose qualifiers were stripped
vocab_uris_rewritten int Subject/object URI rewrites
CategoricalDetector
¶
Detect string literals that represent a bounded category.
A literal is categorical when the same (predicate, object_value)
pair appears in ≥ threshold triples. All such literals are promoted to
IRI resources in the vocabulary namespace.
Example::
ex:Alice ex:is "Director" ┐
ex:Bob ex:is "Director" ┘ threshold=2 → vocab:Director
Source code in src/riverbank/vocabulary/__init__.py
detect(triples)
¶
Identify categorical literals.
:returns: Mapping {(predicate, literal_value): new_iri}.
Source code in src/riverbank/vocabulary/__init__.py
promote(triples, categorical_map)
¶
Rewrite object literals using categorical_map.
:returns: (new_triples, n_promoted)
Source code in src/riverbank/vocabulary/__init__.py
EmbeddingPredicateCanonicali
¶
Post-extraction pass: embed predicate labels, DBSCAN-cluster, rewrite to canonical.
Uses nomic-embed-text (via Ollama) or falls back to all-MiniLM-L6-v2
(sentence-transformers). Groups predicates by semantic similarity using
DBSCAN, then optionally asks the LLM to select the best canonical name for
each cluster.
Example::
was_born_in (0.97 similarity) → has_birth_place
born_in (0.95) → has_birth_place
birthplace (0.91) → has_birth_place
New stats: predicates_canonicalized, predicate_clusters_merged.
Profile YAML::
vocabulary_normalisation:
enabled: true
embedding_canonicalization: true
embedding_canonicalization_threshold: 0.88
embedding_canonicalization_model: "nomic-embed-text"
embedding_canonicalization_llm_rename: true
Falls back gracefully when embedding libraries are unavailable or the LLM call fails — returns the original triples unchanged.
Source code in src/riverbank/vocabulary/__init__.py
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canonicalize(triples, llm_client=None)
¶
Cluster predicates by embedding similarity and rewrite to canonical forms.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
triples
|
list
|
List of :class: |
required |
llm_client
|
Any
|
Optional LLM client (openai.OpenAI compatible) for
canonical name selection. When |
None
|
Returns:
| Type | Description |
|---|---|
list
|
|
int
|
where predicates_canonicalized is the total number of predicate |
int
|
rewrites and predicate_clusters_merged is the number of synonym |
tuple[list, int, int]
|
clusters that were merged. |
Source code in src/riverbank/vocabulary/__init__.py
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FactDecomposer
¶
Detect predicates that encode a qualifier in their local name and decompose them into a base predicate triple plus a separate qualifier triple on the same subject.
Supported qualifier patterns:
- Year:
_in_YYYYor_YYYY→ex:year "YYYY" - Date:
_on_<date>→ex:date "<date>" - Ordinal:
_first,_second,_Nth,_3rd→ex:ordinal "…"
Example::
ex:subject ex:acquired_company_in_2022 ex:Acme
→ ex:subject ex:acquired_company ex:Acme
→ ex:subject ex:year "2022"
Source code in src/riverbank/vocabulary/__init__.py
decompose(triples)
¶
Expand each fact-stuffed triple into two triples.
Handles both end-of-string qualifiers (founded_in_2019) and
mid-word qualifiers (won_first_FA_Cup → won_FA_Cup).
:returns: (expanded_triple_list, n_decomposed)
Source code in src/riverbank/vocabulary/__init__.py
NormalisationConfig
dataclass
¶
Configuration for the vocabulary normalisation pass.
Source code in src/riverbank/vocabulary/__init__.py
NormalisationResult
dataclass
¶
Result returned by :meth:VocabularyNormalisationPass.run.
Source code in src/riverbank/vocabulary/__init__.py
PredicateCollapser
¶
Detect clusters of semantically equivalent predicates and collapse them to a single canonical form.
Two backends are supported:
- deterministic — edit-distance similarity on local predicate names
using :class:
difflib.SequenceMatcher. - llm — single LLM prompt asking for groupings (callable injected at call time so the class remains pure Python with no LLM dependency).
The canonical predicate within each cluster is the most frequently occurring one in the triple buffer.
Source code in src/riverbank/vocabulary/__init__.py
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collapse(triples, collapse_map)
¶
Apply collapse_map to every triple's predicate.
:returns: (new_triples, n_collapsed)
Source code in src/riverbank/vocabulary/__init__.py
find_clusters(triples, llm_client=None)
¶
Return {non_canonical_predicate: canonical_predicate}.
When backend is "llm", llm_client must be a callable that
accepts a list of predicate strings and returns a list of groups
(each group is a list of semantically equivalent predicate strings).
Source code in src/riverbank/vocabulary/__init__.py
URICanonicaliser
¶
Rewrite non-canonical subject/object URIs using owl:sameAs links
present in the triple buffer.
After entity resolution writes owl:sameAs triples, this pass:
- Builds equivalence classes from all
owl:sameAspairs. - Chooses the canonical URI for each class — the one that appears
most frequently as a subject in non-
owl:sameAstriples. - Rewrites every occurrence of a non-canonical URI (as subject or object) to the canonical form.
Example::
# owl:sameAs chain written by entity_resolution
ex:Marie_Curie owl:sameAs ex:Maria_Sklodowska_Curie
ex:M_Curie owl:sameAs ex:Marie_Curie
# URICanonicaliser rewrites all triples to the canonical URI
ex:M_Curie ex:discovered ex:Polonium
ex:Maria_Sklodowska_Curie ex:born_in "Warsaw"
→ ex:Marie_Curie ex:discovered ex:Polonium
→ ex:Marie_Curie ex:born_in "Warsaw"
Source code in src/riverbank/vocabulary/__init__.py
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canonicalise(triples)
¶
Rewrite non-canonical URIs.
:returns: (rewritten_triples, n_rewritten)
Source code in src/riverbank/vocabulary/__init__.py
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VocabularyNormalisationPass
¶
Orchestrate all vocabulary normalisation sub-passes (v0.15.3 + v0.15.5).
Passes applied in order:
- Unicode normalization — decode bare unicode escapes in literals.
- Categorical literal promotion — repeated literals → vocab:* IRIs.
- Predicate cluster collapse — edit-distance or LLM grouping.
- Fact-stuffed predicate decomposition — qualifier stripping.
- Entity URI canonicalisation — owl:sameAs rewriting (optional).
- Embedding-based predicate canonicalization (v0.15.5, optional) — DBSCAN clusters of semantically equivalent predicates rewritten to a canonical form using nomic-embed-text + optional LLM renaming.
- Deduplication — keep highest-confidence triple per (s, p, o) key.
Usage::
pass_ = VocabularyNormalisationPass.from_profile(profile)
result = pass_.run(triple_buffer)
# result.triples — normalised triple list
# result.vocab_literals_promoted, .vocab_predicates_collapsed, …
# result.predicates_canonicalized, .predicate_clusters_merged (v0.15.5)
The pass is idempotent: running it twice on the same buffer produces the same result as running it once (assuming no new categorical clusters emerge after the first pass).
Source code in src/riverbank/vocabulary/__init__.py
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from_profile(profile, settings=None)
classmethod
¶
Construct from a :class:~riverbank.pipeline.CompilerProfile.
Source code in src/riverbank/vocabulary/__init__.py
run(triples, llm_client=None)
¶
Apply all enabled sub-passes to triples and return a result.
:param triples: List of
:class:~riverbank.prov.ExtractedTriple objects.
:param llm_client: Optional callable for LLM-guided predicate
collapsing. Must accept list[str] of predicate IRIs and
return list[list[str]] of equivalence groups. Only used
when predicate_collapse_backend: "llm" is configured.
:returns: :class:NormalisationResult with normalised triples and
per-normalisation counts.
Source code in src/riverbank/vocabulary/__init__.py
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build_llm_predicate_collapser(settings, profile)
¶
Return an LLM callable for predicate grouping, or None on failure.
The callable accepts a list of predicate IRI strings and returns a list
of equivalence groups (each group is a list of semantically equivalent
predicate strings). Used by :class:PredicateCollapser in llm mode.
Falls back to None (caller uses deterministic mode) when the openai
package is unavailable or the LLM call is not configured.
Source code in src/riverbank/vocabulary/__init__.py
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