School of Computer Science
Scone Knowledge Base
Scott E. Fahlman
April 14, 2005
Goals for Scone
• Build a practical “knowledge base” (KB) engine and toolkit
that can be used in any number of applications.
• Semantic network model: nodes are entities, links are
statements.
• Emphasis on scalability and ease of use.
– A few million entities and relations on a high-end workstation.
– Parallelizable if you want more.
• Implemented in Common Lisp, runs on 32-bit or 64-bit
workstations.
• Will release as open-source, with a tutorial book.
• Alicia Tribble (Ph.D. student) working on NL input of
knowledge.
April 14, 2005
2
Current Cabilities
• Multiple-inheritance hierarchy with exceptions.
• Efficient detection of type violations.
• Mapping of concepts to words is many-to-many.
• User-defined roles and relations.
• Can attach meta-knowledge to any node or link.
• Multiple contexts: hierarchical & lightweight.
• Can represent numerical weights and probabilities.
• Programmer-level document.
• Current “core” KB is minimal.
• Machinery for episodic memory exists, but is minimal.
April 14, 2005
3
Multiple Contexts
• Each link (statement) in SCONE is tied to the
context in which it is true.
• Contexts form an inclusion hierarchy. Each starts
as a clone, then adds or cancels some information.
• To activate a context, mark it and all included
contexts, then mark all active statements. Only
these link are active.
• So multiple contexts are efficient, lightweight, and
heavily used for reasoning about alternative states
of the universe, real or hypothetical. (“What if…”)
• The multiple-context mechanism is used to
implement actions and events.
April 14, 2005
4