Knowledge graph
Also: KG, GraphRAG, graph RAG
Entities are nodes and typed relationships are edges, so facts are explicit and can be chained. In graph RAG, retrieval traverses these links from the entities in a question, which answers multi-hop questions that similarity search over isolated chunks misses.
Example
From (Ada Lovelace, founded, Analytica Inc.) and (Analytica Inc., makes, Engine X), a two-hop traversal answers "Who founded the company that makes Engine X?" with Ada Lovelace.