Knowledge Graph
A knowledge graph is a structured representation of entities (such as people, places, events, concepts) and the relationships between them, modeled as nodes and edges. This format allows machines to integrate and reason over complex, interconnected information.
Background
The concept became mainstream with Google’s Knowledge Graph (2012), which enhanced search by linking queries to real-world entities. Today, knowledge graphs are core to AI-driven search, recommendations, and semantic reasoning.
Applications
- Search engines: connecting a query to related entities.
- Recommendation systems: linking users, products, and contexts.
- Healthcare: mapping interactions between drugs, diseases, and patients.
Strengths and challenges
- ✅ Provide semantic context beyond raw data.
- ✅ Enhance explainability of AI systems.
- ❌ Building and maintaining them requires significant effort.
- ❌ Data incompleteness or bias can reduce effectiveness.
Knowledge graphs can be seen as the bridges between raw data and human-like understanding. By connecting entities through explicit relationships, they allow AI systems to answer not only “what” but also “how” and “why.” For instance, instead of simply retrieving documents about “Einstein,” a knowledge graph can highlight that he was a physicist, authored the theory of relativity, and was awarded the Nobel Prize in 1921.
In industry, they serve as the backbone for enterprise knowledge management. Large organizations use them to connect scattered data sources—emails, reports, databases—into a coherent network, making it easier to detect hidden connections and support decision-making.
Yet, building robust knowledge graphs is far from trivial. Challenges include entity disambiguation (is “Paris” the city in France or the celebrity?), handling evolving information, and scaling to billions of nodes. Increasingly, hybrid approaches combine symbolic knowledge graphs with neural embeddings to capture both structured logic and statistical patterns.
📚 Further Reading
- Hogan, A. et al. (2021). Knowledge Graphs. ACM Computing Surveys.
