ontology-design

Ontology Design

Model domain knowledge through classes, properties, and relationships.

Core Components

Component	Purpose	Example
Class	Category of things	Person, Product
Property	Attribute of class	name, price
Relationship	Connection between classes	owns, partOf
Instance	Specific entity	John, iPhone15

Relationship Types

Type	Notation	Example
Is-a (inheritance)	subClassOf	Dog is-a Animal
Has-a (composition)	hasPart	Car has-a Engine
Uses (association)	uses	Person uses Tool
Instance-of	type	Fido instance-of Dog

Taxonomy Levels

Kingdom
  └── Phylum
        └── Class
              └── Order
                    └── Family
                          └── Genus
                                └── Species

Design Template

## Class: [Name]

**Description**: [purpose]
**Parent**: [superclass]

### Properties
| Name | Type | Required | Description |
|------|------|----------|-------------|
| id | string | yes | Unique identifier |
| name | string | yes | Display name |

### Relationships
| Relation | Target | Cardinality |
|----------|--------|-------------|
| belongsTo | Category | many-to-one |
| contains | Item | one-to-many |

Design Principles

• MECE: Mutually exclusive, collectively exhaustive
• Single inheritance preferred: Avoid diamond problem
• Normalize: Reduce redundancy
• Domain-driven: Match real-world concepts

Anti-Patterns

• God class (too many responsibilities)
• Orphan classes (no relationships)
• Circular dependencies
• Over-abstraction