MLKN.lab · Polyhierarchy
Polyhierarchy
6 Core Domains → 25 Disciplines → 235 Subdisciplines → Topics & Concepts
Overview
A Polyhierarchical and Mutli-Layered Knowledge Network
The structural architecture of MLKN.lab is anchored in a formalized, five-tier ontological taxonomy designed to map the multi-scale density of global science. Moving past the cognitive limitations of linear, mono-hierarchical indexing, this taxonomy employs a high-fidelity, polyhierarchical framework that allows complex scientific entities and boundary concepts to map concurrently across multiple fluid conceptual pathways.
The structural schema is partitioned into five discrete abstraction layers (5 Ontological Knowledge Layers): expanding from Layer 1 (6 Epistemological Core Domains) which establish macro-disciplinary baselines, down through Layer 2 (25 Academic Disciplines) and Layer 3 (235 Specialized Subfields), into the granular clusters of Layer 4 (Thematic Domains) and Layer 5 (Core Concepts). This stratified taxonomy acts as the structural blueprint for our knowledge graphs, providing the mathematical and conceptual scaffolding necessary to trace cross-domain knowledge diffusion, measure cluster modularity, and systematically isolate under-explored interdisciplinary frontiers.
Conceptual Foundations
Multilayer Networks & Hypergraphs in MLKN.lab
MLKN.lab's polyhierarchical framework is built on two complementary mathematical structures: multilayer networks (Layers 1-4) and hypergraphs (Layers 4-5). This dual approach allows us to model both hierarchical relationships (e.g., disciplines containing subdisciplines) and complex, non-linear connections (e.g., concepts spanning multiple fields).
Multilayer Network (Layers 1-4)
Layers 1-4 form a hierarchical network where:
- Layer 1 (Core Domains): 6 broad categories (e.g., Natural Sciences)
- Layer 2 (Disciplines): 25 fields (e.g., Physics)
- Layer 3 (Subdisciplines): 235 specialized areas (e.g., Quantum Mechanics)
- Layer 4 (Thematic Domains): Granular clusters (e.g., Quantum Field Theory)
This structure enables top-down analysis of knowledge diffusion across traditional academic boundaries.
Hypergraph (Layers 4-5)
Layers 4-5 form a hypergraph where:
- Layer 4 (Thematic Domains): Connects to multiple disciplines
- Layer 5 (Concepts): Links to multiple thematic domains
This allows non-linear mapping of concepts that span multiple fields (e.g., "Machine Learning" in CS, Math, and Neuroscience).
Combined Framework
The multilayer network (Layers 1-4) and hypergraph (Layers 4-5) work together to:
- Preserve disciplinary hierarchy (e.g., Physics → Quantum Mechanics)
- Enable cross-disciplinary connections (e.g., Quantum Mechanics → Chemistry)
- Support multi-scale analysis (from domains to concepts)
OpenAlex Integration
Our implementation uses OpenAlex data to:
- Map 25 disciplines to 6 core domains
- Identify 235 subdisciplines with cross-domain connections
- Track 320K+ connections between concepts
This creates a data-driven polyhierarchy that reflects real-world scientific relationships.
For a rigorous mathematical treatment of these concepts, see our MLKN.model - Mathematical Foundations page.
Ontological Knowledge Layers
5 Knowledge Layers
The MLKN.lab polyhierarchy organizes scientific knowledge into 5 layers:
Core Domains
Layer 1: 6 broad categories (e.g., Social Sciences & Humanities, Natural Sciences).
Academic Disciplines
Layer 2: 25 fields (e.g., Psychology, Computer Science).
Subdisciplines
Layer 3: 235 specialized areas (e.g., Cognitive Psychology, AI Ethics).
Core Thematic Domains
Layer 4: Thematic groupings within subdisciplines.
Main Concepts
Layer 5: Specific topics or ideas (e.g., "Attention", "Neural Networks").
Epistemological Core Domains
6 High-Level Scientific Domains
Engineering & Technology
- Chemical Engineering
- Energy
- Engineering
- Materials Science
Formal Sciences
- Computer Science
- Mathematics
Health & Medical Sciences
- Dentistry
- Health Professions
- Medicine
- Nursing
- Pharmacology, Toxicology and Pharmaceutics
Life Sciences
- Agricultural and Biological Sciences
- Biochemistry, Genetics and Molecular Biology
- Immunology and Microbiology
- Neuroscience
- Veterinary
Natural Sciences
- Chemistry
- Earth and Planetary Sciences
- Environmental Science
- Physcis and Astronomy
Social Sciences & Humanities
- Arts and Humanities
- Decision Sciences
- Economics, Econometrics and Finance
- Psychology
- Social Sciences
Academic Disciplines
25 academic disciplines
Chemical Engineering
Bioengineering, Catalysis, Chemical Health and Safety, Filtration and Separation, Fluid Flow and Transfer Processes...
ExploreEnergy
Energy Engineering, Fuel Technology, General Energy, Nuclear Energy and Engineering, Renewable Energy, Sustainability and Environment.
ExploreEngineering
Aerospace Engineering, Architecture, Automotive Engineering, Biomedical Engineering, Building and Construction...
ExploreMaterials Science
Biomaterials, Ceramics and Composites, Electronic, Optical and Magnetic Materials, General Materials Science, Material Chemistry...
ExploreMathematics
Algebra and Number Theory, Applied Mathematics, Computational Mathematics, Discrete Mathematics and Combinatorics, Geometry and Topology...
ExploreComputer Science
Artificial Intelligence, Computational Theory, Computer Graphics, Computer Networks, Computer Science Applications...
ExploreHealth Professions
Complementary and Manual Therapy, Emergency Medical Services, General Health Professions, Health Information Management, Medical Laboratory Technology...
ExploreMedicine
Anatomy, Anesthesiology and Pain Medicine, Biochemistry, Cardiology and Cardiovascular Medicine, Complementary and Alternative Medicine, Critical Care and Intensive Care Medicine...
ExploreNursing
Issues, Ethics and Legal Aspects, Leadership and Management, Nutrition and Dietetics, Research and Theory.
ExplorePharmacology, Toxicology, and Pharmaceutics
Drug Discovery, Pharmaceutical Science, Pharmacology, Toxicology.
ExploreAgricultural and Biological Sciences
Agronomy and Crop Science, Animal Science and Zoology, Aquatic Science, Ecology, Evolution Behavior and Systematics, Food Science...
ExploreBiochemistry, Genetics, and Molecular Biology
Aging, Biochemistry, Biophysics, Biotechnology, Cancer Research...
ExploreImmunology and Microbiology
Applied Microbiology and Biotechnology, Immunology, Microbiology, Parasitology, Virology.
ExploreNeuroscience
Behavioral Neuroscience, Biological Psychiatry, Cellular and Molecular Neuroscience, Developmental Neuroscience...
ExploreChemistry
Analytical Chemistry, Electrochemistry, Inorganic Chemistry, Organic Chemistry, Physical and Theoretical Chemistry...
ExploreEarth and Planetary Sciences
Atmospheric Science, Earth-Surface Processes, Geochemistry and Petrology, Geology, Geophysics...
ExploreEnvironmental Science
Ecological Modeling, Ecology, Environmental Chemistry, Environmental Engineering, Global and Planetary Change...
ExplorePhysics and Astronomy
Acoustics and Ultrasonics, Astronomy and Astrophysics, Atomic and Molecular Physics, and Optics, Condensed Matter Physics, Instrumentation...
ExploreArts and Humanities
Archeology, Classics, Conservation, General Arts and Humanities, History...
ExploreDecision Science
General Decision Sciences, Information Systems and Management, Management Science and Operations Research, Statistics, Probability and Uncertainty.
ExploreEconomics, Econometrics and Finance
Economics and Econometrics, Finance, General Economics, Econometrics and Finance.
ExplorePsychology
Applied Psychology, Clinical Psychology, Developmental and Educational Psychology, Experimental and Cognitive Psychology, General Psychology...
ExploreVisualization
Static Preview of the Polyhierarchy
Below is a static preview of the hierarchy. An interactive version is coming soon!
Exploration
Click on a core domain below to see its disciplines and subdisciplines:
Get in Touch
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