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Enhanced flexible-graphrag: RDF/Ontology Support with PropertyGraphIndex

Executive Summary

Enhance flexible-graphrag to support: 1. Ontology-Driven Knowledge Graph Extraction using RDFlib + LlamaIndex's SchemaLLMPathExtractor 2. 8 Property Graph Databases (already supported, with improved schema integration) 3. RDF Store Targets (Ontotext GraphDB, Apache Fuseki, Oxigraph, Oracle, etc.) via custom SPARQL store connectors 4. SPARQL Query Interface for querying both extracted graphs and wrapped property graphs 5. RDF Export/Import capabilities (secondary but important for interoperability)

Architecture Overview

                           Document Sources
                           (PDF, DOCX, etc.)
                                  v
                    +------------------------------+
                    |  Flexible-GraphRAG Ingestion |
                    |    (Docling Processing)      |
                    +--------------+---------------+
                                   v
                    +------------------------------+
                    |  Ontology Integration Layer  |
                    |  1. Load RDF ontologies      |
                    |  2. Extract entity/relation  |
                    |     types via SPARQL         |
                    |  3. Build schema for LLM     |
                    +--------------+---------------+
                                   v
      +-----------------------------------------------------+
      |    LlamaIndex PropertyGraphIndex with Extractors    |
      +-----------------------------------------------------+
      | SchemaLLMPathExtractor (ontology-guided)            |
      |   +- Validates against ontology schema              |
      | SimpleLLMPathExtractor (free-form)                  |
      | ImplicitPathExtractor (structural)                  |
      | DynamicLLMPathExtractor (guided LLM)                |
      +----------------+------------------+
                       |
                       v
    +----------------------------+   +---------------------------+
    | Property Graph Stores      |   | RDF Store Targets         |
    +----------------------------+   +---------------------------+
    | - Neo4j                    |   | - Ontotext GraphDB        |
    | - Ladybug                  |   | - Apache Fuseki           |
    | - FalkorDB                 |   | - Oxigraph                |
    | - ArcadeDB                 |   | - Oracle SPARQL           |
    | - MemGraph                 |   | - Virtuoso                |
    | - NebulaGraph              |   | - Custom SPARQL Endpoint  |
    | - Amazon Neptune           |   |                           |
    | - Neptune Analytics        |   |                           |
    +----------------------------+   +---------------------------+
                 |                               |
                 +---------------+---------------+
                                 |
                                 v
                    +------------------------+
                    |  Unified Query Engine  |
                    +------------------------+
                    | Cypher (Property Graph)|
                    | SPARQL (RDF Stores)    |
                    | Text-to-Cypher/SPARQL  |
                    | Hybrid Retrieval       |
                    +------------------------+
                                 v
                    +------------------------+
                    |  Results & Retrieval   |
                    |  (Existing UI clients) |
                    +------------------------+