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Structured extraction

As explained in Natural Language Processing in Action, Second Edition

Information extraction is the automatic identification and structuring of facts, entities, and relations from unstructured text.

Structured extraction turns unstructured text into usable facts, entities, and relationships. It supports factual question answering, knowledge-graph construction, and checks on generated language-model output. section 1.10 section 11.1

A practical extraction pipeline combines complementary techniques:

  • Use regular expressions and manually defined patterns when compact condition checks can reliably capture key information or enforce logical actions. section 11.1.1
  • Identify named entities, resolve references such as pronouns, and extract relations connecting entities in a sentence. section 11.3
  • Apply part-of-speech tagging and dependency parsing to expose relationships between entities. section 11.11
  • Store extracted relationships in a knowledge graph so systems can retrieve facts and ground their reasoning. section 11.1 section 11.11

From a reminder request to graph facts

A reminder command requires more than recognizing words: extraction must connect the person entity to the command, infer the chatbot as the implied subject, and interpret “next Monday” as a future date. A separate workflow tests extraction on a cached Wikipedia article about Timnit Gebru, providing realistic text for identifying entities and relations. section 11.3

Figure 11.2 Four stages of knowledge extraction
figure

Use the four-stage pipeline figure to navigate the major components of knowledge extraction. section 11.3

How Natural Language Processing in Action, Second Edition covers it

How deep it goes
Combines patterns, named-entity recognition, coreference resolution, relation extraction, tagging, and parsing, without detailing model internals.
Examples
Demonstrates reminder interpretation and extraction experiments on a Wikipedia article about Timnit Gebru.
What it assumes
Assumes basic natural-language-processing familiarity while introducing extraction stages through patterns, entities, references, and relations.
What you can do after
Build it with spaCy components, combine extracted results, and populate or query a knowledge graph.
How it connects
Connects regular expressions, named entity recognition, coreference resolution, relation extraction, dependency parsing, and knowledge graphs.

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