Why Your Agent’s Brain Needs a Playbook: Practical Wins from Using Ontologies - Jesús Barrasa, Neo4j
Jun 27, 2025 · 13:54
Jesús Barrasa, AI Field CTO at Neo4j, argues that ontologies are the secret weapon for building robust GraphRAG applications, providing both a formal, implementation-agnostic schema for knowledge graph creation and a dynamic data layer that drives retriever behavior. He explains how ontologies replace rigid code-orchestrated workflows and chaotic LLM-generated ones by guiding entity extraction from unstructured data and mapping structured sources into a property graph. During retrieval, storing the ontology in the graph enables dynamic Cypher queries that automatically navigate contextualizing relationships — such as "acted-in" rather than "directed" — based on annotated subproperties, without hard-coded logic. This allows developers to change retrieval behavior on the fly by modifying the ontology as a data artifact. The talk covers two practical wins: using ontologies as a shared domain model for graph construction, and leveraging them to build adaptive, schema-driven retrievers that improve result completeness and relevance.
