Learn
Ontology Engineering
The formal track. Everything the first course had to leave out, at the depth where you can defend it.
Start here
This is the companion to Ontology & Fabric IQ, written for someone who already models and now wants the formal apparatus. Every page opens on a claim you thought was settled, states the real result with its actual notation, then hands you a demonstration you can run yourself.
Take the first course first
These pages assume you can already define an entity, bind it, and read a graph. If any of that is new, read Ontology & Fabric IQ first. Nothing here re-teaches it.
Notation is glossed, never bare
Where a result needs real logic notation, you get the notation and a plain sentence saying what it means. Read both. The notation is what makes the claim checkable; the sentence is what makes it sayable out loud.
Run every set piece
Each page carries one interactive demonstration built to change your mind in under a minute. They are the point of the track, not decoration. Several of them contradict something the page just let you assume.
Your progress
Tick a concept here, or mark it learned on its page, and the meter fills in. Saved in this browser.
Part 1 — What an ontology is
Three chapters, no assumed knowledge. By the end you can say what the word means and defend it.
1. What an ontology really is
FoundationsThe famous one-line definition, taken apart word by word, using a warehouse you can picture.
2. The ontology spectrum
FoundationsA list, a taxonomy, and an ontology are different things. Here is the ladder, and where most projects stop.
3. What your model says exists
FoundationsEvery model quietly claims some things are real and others are not. Learn to read that claim.
Part 2 — Things
Five chapters on the hardest question in modeling: what counts as one thing, and how to prove you got it right.
4. The biggest boxes
Formal ontologyBefore your Customer and your Freezer, there are a handful of categories everything falls into. Knowing them saves you from arguments.
5. Four questions to ask about any class
Formal ontologyCan a thing stop being one of these and survive? Four questions like that, and they settle arguments that used to take hours.
6. Checking a hierarchy
Formal ontologyTurn the four questions into four rules, run them over a real hierarchy, and watch two lines fail.
7. Kinds, roles, and phases
Formal ontologyCustomer is not a kind of thing. It is a role. Getting this wrong creates duplicate people, and here is exactly how.
8. Identity is not a primary key
Formal ontologyA key tells the database which row. An identity criterion tells you which thing. They are not the same, and the gap is where master data breaks.