Relation Extraction & Knowledge Graph Construction

NER found the entities. Entity linking anchored them. Relation extraction finds the edges between them. A knowledge graph is the sum of nodes, edges, and their provenance.

Build 1 hr Python

Prerequisites: Phase 5 · 06 (NER), Phase 5 · 25 (Entity Linking)

#The Problem

An analyst reads: "Tim Cook became CEO of Apple in 2011." Four facts:

  • (Tim Cook, role, CEO)
  • (Tim Cook, employer, Apple)
  • (Tim Cook, start_date, 2011)
  • (Apple, type, Organization)

Relation Extraction (RE) turns free text into structured triples (subject, relation, object). Aggregate across a corpus and you have a knowledge graph. Aggregate and query and you have a reasoning substrate for RAG, analytics, or compliance audits.

The 2026 problem: LLMs extract relations enthusiastically. Too enthusiastically. They hallucinate triples that the source text does not support. Without provenance, you cannot tell real triples from plausible fiction. The 2026 answer is AEVS-style anchor-and-verify pipelines.

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The text and code of this lesson are based on AI Engineering from Scratch by Rohit Ghumare, MIT licensed.