Intro to Taxonomy, to Thesaurus, to Ontology, to Knowledge Graph

Joe Hoeller
3 min readJun 26, 2024

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Hello wonderful people, today, we’re exploring the intricate evolution from taxonomies to thesauri, ontologies, and finally, knowledge graphs. Each stage in this progression adds layers of sophistication to how we structure and understand data, ultimately empowering us to derive more actionable insights. For a seasoned executive, understanding these transitions can provide a strategic advantage in leveraging data-driven decision-making.

Start with Your Use Case

Before diving into modeling, it’s imperative to identify your use case. For instance, consider a scenario where a manufacturer needs to understand the components and parts of their vehicles. This use case will guide the structuring and refinement of our models.

Stage 1: Taxonomy

A taxonomy organizes data into hierarchical relationships such as broader and narrower terms or parent-child relationships. For example, in a vehicle manufacturer scenario, vehicles might be categorized into passenger and sports vehicles, with specific models like Mustangs and Raptors falling under these categories. Taxonomies help in identifying and grouping related items, providing a foundational structure that supports robust data categorization.

Stage 2: Thesaurus

Building on the taxonomy, a thesaurus adds synonyms, alternative terms, and “see also” relationships, enhancing the context and connectivity of your data. This stage enriches the metadata, making it easier for both humans and machines to understand and navigate the data. For instance, the term “electric motor” in your taxonomy can be linked with synonyms and related terms from different databases or user inputs, enhancing search capabilities and semantic understanding.

Stage 3: Ontology

Ontologies take the thesaurus to the next level by explicitly defining the relationships between entities and their attributes. Unlike taxonomies and thesauri, which are more about categorization and synonyms, ontologies define the nature of relationships (e.g., “has part,” “manufactured in”). This stage involves identifying universal categories and refining them to answer specific questions. For example, if tracking vehicles, you might center your ontology around the vehicle identification number (VIN), linking it to parts, manufacturing locations, and transactions.

Deep Insight: Enhanced Predictive Analytics

A crucial insight at this stage is the potential for enhanced predictive analytics. By defining detailed relationships and attributes, an ontology allows for more accurate predictive models. For instance, understanding the relationship between specific vehicle parts and failure rates can help in predictive maintenance. This is actionable as it directly impacts operational efficiency and cost management.

Stage 4: Knowledge Graph

A knowledge graph populates the ontology with instance data, creating a rich, interconnected dataset. This graph can include inferred relationships and additional nodes that flesh out the network. Using your ontology, you can link specific electric motors to vehicles, manufacturing plants, and supply chains, revealing hidden connections and enabling advanced data analysis. This stage supports sophisticated queries and semantic search, making it invaluable for large-scale data integration and retrieval.

Actionable Insight: Real-Time Data Integration

For a business executive, the ability to integrate real-time data streams into a knowledge graph can revolutionize data-driven strategies. By continuously updating the knowledge graph with live data from IoT devices, social media, or transactional systems, you can achieve real-time insights into user behavior, operational anomalies, and market trends. This integration is not just a technical enhancement but a strategic move to stay ahead in dynamic environments.

Key Considerations

  1. Metadata and Relationships: Each stage adds more metadata and relationships, enhancing data context and usability.
  2. Refinement and Validation: Continuously refine your model, checking for logical consistency and alignment with business needs.
  3. Handling Instances: Differentiate between universal concepts (e.g., “cat”) and specific instances (e.g., “my cat Garfield”) to maintain clarity.
  4. Avoid Orphan Nodes: Ensure all nodes are connected to avoid data silos and technical debt. This is also known as entity resolution.

Advanced Tools

For those looking to dive deeper, RDF* (RDF star) and SHACL (Shapes Constraint Language) are powerful tools. RDF* extends RDF’s expressiveness by embedding triples within triples, useful for adding metadata like provenance or temporal information. SHACL provides a robust mechanism to validate RDF graphs, ensuring data quality and conformance to expected structures.

Conclusion

By understanding and implementing these evolutionary stages, you can build robust, context-rich data structures that support advanced data analysis and strategic decision-making. Whether you stop at a taxonomy or evolve to a knowledge graph, each stage adds incremental value. Leveraging tools like RDF* and SHACL further enhances the precision and usability of your data models.

For a deeper dive into each stage, check out the linked resources and previous discussions. Should you have any questions or require further insights, feel free to reach out on LinkedIn.

Thank you for your time, and let’s continue driving innovation through sophisticated data modeling!

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Joe Hoeller

Computer Vision Engineer and Accelerated GPU Computing Expert