Strong Slot and Filler Structures

Strong Slot and Filler Structures typically:

• Represent links between objects according to more rigid rules.
• Specific notions of what types of object and relations between them are provided.
• Represent knowledge about common situations.

CYC

What is CYC?

• An ambitious attempt to form a very large knowledge base aimed at capturing commonsense reasoning.
• Initial goals to capture knowledge from a hundred randomly selected articles in the EnCYClopedia Britannica.
• Both Implicit and Explicit knowledge encoded.
• Emphasis on study of underlying information (assumed by the authors but not needed to tell to the readers.

Example: Suppose we read that Wellington learned of Napoleon's death

Then we (humans) can conclude Napoleon never new that Wellington had died.

How do we do this?

We require special implicit knowledge or commonsense such as:

• We only die once.
• You stay dead.
• You cannot learn of anything when dead.
• Time cannot go backwards.

Why build large knowledge bases:

Brittleness

-- Specialised knowledge bases are brittle. Hard to encode new situations and non-graceful degradation in performance. Commonsense based knowledge bases should have a firmer foundation.

Form and Content

-- Knowledge representation may not be suitable for AI. Commonsense strategies could point out where difficulties in content may affect the form.

Shared Knowledge

-- Should allow greater communication among systems with common bases and assumptions.

How is CYC coded?

• By hand.
• Special CYCL language:
• LISP like.
• Frame based
• Multiple inheritance
• Slots are fully fledged objects.
• Generalised inheritance -- any link not just isa and instance.