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SHACL Bridges

N-to-m semantic mapping via SHACL shapes with SPARQL CONSTRUCT rules.

What is this?

SHACL Bridges transforms instance data that conforms to one ontological design pattern into instance data that conforms to a different design pattern — without touching the source data and without requiring a full ontology alignment.

It is not a 1-to-1 class crosswalk. It handles n-to-m structural mappings: one source class can fan out to multiple target classes, relationships can be rerouted, and new connections can be introduced between transformed instances.

Why not SSSOM or an alignment tool?

Standard mapping tools (SSSOM, OWL equivalence axioms, YARRRML) operate on concepts in isolation. They answer "class A is equivalent to class B." They cannot express "a chain of three classes connected by two specific properties in ontology A corresponds to a different chain of three classes in ontology B."

SHACL Bridges expresses exactly that:

  1. A source pattern defines what the source data must look like (S-P-O triples).
  2. A target pattern defines what to construct.
  3. A class map aligns source classes to target classes with justification.
  4. A SHACL sh:SPARQLRule is generated and applied via pyshacl.
  5. The diff between the inferred base graph and the expanded graph gives only the newly bridged triples.

Quick start

pip install shacl-bridges  # once published
# or: uv pip install -e ".[dev]" from the repo root

from shacl_bridges import load_mapping, select_root_class, check_connectivity
from shacl_bridges import generate_shacl, run_bridge_from_files, save_result

mapping = load_mapping("bridge.yaml")
root = select_root_class(mapping.source_pattern.triples, mapping.root_class())

issues = check_connectivity(mapping.source_pattern.triples, root)
if issues:
    raise ValueError(f"Disconnected nodes from root {root!r}: {issues}")

shacl_ttl = generate_shacl(mapping, root)
open("bridge.ttl", "w").write(shacl_ttl)

result = run_bridge_from_files("data.ttl", "bridge.ttl")
save_result(result, "expanded.ttl", "diff.ttl")
print(f"Bridge added {len(result.diff_graph)} new triples.")

Or use the CLI:

shacl-bridges validate  bridge.yaml          # check the mapping
shacl-bridges diagram   bridge.yaml          # print Mermaid diagram
shacl-bridges generate  bridge.yaml -o shape.ttl
shacl-bridges run       bridge.yaml data.ttl

See the Process → Experiment example for a full walkthrough.