Building a Complex Ontology Using The Big Bang Theory

This post explains what an ontology is in depth. It defines related terms such as domain, namespace, class, property, individual, and scope. Then it walks through building a complex ontology using the world of The Big Bang Theory (the television sitcom) as our example.

📚 Key Definitions

Ontology (in information science) is a formal representation of concepts, classes, relationships, and individuals in a domain. It specifies names, definitions, and how those terms relate to each other. See the Wikipedia article on ontology.

Domain refers to the subject area or universe that the ontology covers. It defines the boundaries of what concepts and instances are included or excluded.

Namespace is a way of organizing and qualifying names (classes, properties, individuals) to prevent ambiguity. It usually involves a URI (Uniform Resource Identifier) or prefix that indicates where the terms come from. For example: schema:Person where schema refers to schema.org. Namespaces help avoid name collisions.

Class (or Concept) is a category or type of thing in the domain. Examples: Person, Location, Profession.

Subclass is a more specific class under a broader one. For instance, Scientist is a subclass of Person.

Individual (or Instance) is a specific entity belonging to a class. For example, Sheldon_Cooper is an individual of class Person.

Property describes a relationship between individuals (object property) or a characteristic (datatype property). Example of object property: hasProfession, datatype property: age.

Scope defines how much of the domain the ontology covers. It can be narrow or wide. It determines what classes, properties, and individuals are included.

📺 What Is The Big Bang Theory?

The Big Bang Theory is an American sitcom created by Chuck Lorre and Bill Prady. It aired from September 24, 2007 to May 16, 2019, spanning twelve seasons and 279 episodes. Learn more here.

The series follows two physicists, Leonard Hofstadter and Sheldon Cooper, who live together in Pasadena and work at Caltech. Their lives change when Penny, an aspiring actress, moves in across the hall. Over time, the friend group expands to include Howard, Raj, Amy, and Bernadette. The show blends science, social awkwardness, pop culture, and romantic entanglements into a highly successful comedy format.

🧱 Step by Step: Building an Ontology for The Big Bang Theory

Step 1: Choose Domain & Scope

We define our domain as the fictional world of The Big Bang Theory. Our scope will include:

Main and recurring characters
Professions and academic fields
Key locations
Personal and professional relationships

Step 2: Identify Core Classes

Person
Gender
Profession
AcademicField
Location
RelationshipType
Episode

Step 3: Define Subclasses

Gender → Male, Female
Profession → Scientist, Waiter, GraduateStudent, Engineer, ComicBookStoreOwner, Dermatologist, Microbiologist, Neuroscientist, Astronaut, Psychiatrist, Actor
Location → Apartment, University, Restaurant, Store, Hospital, TV_Studio
AcademicField → TheoreticalPhysics, ExperimentalPhysics, Engineering, Microbiology, Neuroscience, Astrophysics, Dermatology, Psychology, PlasmaPhysics

Step 4: Define Properties

hasGender: Person → Gender
hasProfession: Person → Profession
fieldOfStudy: Person → AcademicField
worksAt: Person → Location
frequentlyVisits: Person → Location
romanticallyInvolvedWith: Person → Person
friendOf: Person → Person

Step 5: Add Individuals (Instances)

Sheldon_Cooper: Male, Scientist, TheoreticalPhysics, Caltech
Leonard_Hofstadter: Male, Scientist, ExperimentalPhysics, Caltech
Penny: Female, Waiter, —, The Cheesecake Factory
Howard_Wolowitz: Male, Engineer, Engineering, Caltech
Raj_Koothrappali: Male, Scientist, Astrophysics, Caltech
Amy_Farrah_Fowler: Female, Neuroscientist, Neuroscience, Caltech
Bernadette_Rostenkowski: Female, Microbiologist, Microbiology, ZanGen Pharmaceuticals
Stuart_Bloom: Male, ComicBookStoreOwner, —, Comic Book Store
Leslie_Winkle: Female, Scientist, ExperimentalPhysics, Caltech
Barry_Kripke: Male, Scientist, PlasmaPhysics, Caltech
Emily_Sweeney: Female, Dermatologist, Dermatology, Hospital
Beverly_Hofstadter: Female, Psychiatrist, Psychology, University
Wil_Wheaton: Male, Actor, —, TV_Studio

Step 6: Use Namespaces & URIs

We define a namespace like bbt: mapped to http://example.org/bbt#. Example terms:

bbt:Sheldon_Cooper
bbt:hasProfession
bbt:Caltech

Step 7: Add Inverse Relationships

romanticallyInvolvedWith is symmetrical
worksAt ↔ employs
hasProfession ↔ professionOf

Step 8: Sample Relationship Triples

@prefix bbt: <http://example.org/bbt#> .

bbt:Sheldon_Cooper a bbt:Person ;
  bbt:hasGender bbt:Male ;
  bbt:hasProfession bbt:Scientist ;
  bbt:fieldOfStudy bbt:TheoreticalPhysics ;
  bbt:worksAt bbt:Caltech ;
  bbt:friendOf bbt:Leonard_Hofstadter .

bbt:Penny a bbt:Person ;
  bbt:hasGender bbt:Female ;
  bbt:hasProfession bbt:Waiter ;
  bbt:frequentlyVisits bbt:Apartment_4A ;
  bbt:romanticallyInvolvedWith bbt:Leonard_Hofstadter .

✅ Best Practices

Use reusable class names and properties
Follow clear naming conventions
Add documentation and comments
Structure with versioned namespaces
Test with tools like Protégé

📌 Summary

We defined and explained ontology concepts, then built a fictional ontology around The Big Bang Theory. We modeled characters, relationships, professions, and locations using classes, properties, and individuals. This example shows how ontologies can help structure knowledge in a consistent and reusable way.

If you can model a sitcom, you can model recipes, research, apps — anything with structured meaning.