Intelligent Systems Lecture Notes

7 December 2011 • Frames

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Outline

How Would You Behave?

Analogous Reasoning

• Teach a machine to learn circumstances, and then generalize to new, but related, circumstances.
  • And then usefully operate in those circumstances.
• Marvin Minsky in 1975 suggested a structured, hierarchical representation called frames.
  • The motivation was psychological: how do people do it?
  • Model that approach in machines.

Frame

• A frame is a named set of slots.

Slots

• A slot is a name-value pair.

Frame Types

• There are two frame types: individual and generic frames.

Generic Frames

• A generic frame represents a category for a collection of instances.
  • The category characterizes the instances in some way.
• The :isa slot marks a generic frame.

Individual Frames

• An individual frame represents a particular instance of category.
• The :instanceof slot marks an individual frame.
  • The :instanceof filler is the generic-frame name describing the category.

Attached Procedures

• A generic-frame slot may have attached procedures.
• An attached procedure has
  • a trigger to start execution, and
  • a code body to execute when triggered.

Inheritance

• Psychologically, people build mental stereotypes and modify them (or not) to fit instances.
• Inheritance provides the corresponding mechanism in frames.
  • Fillers not resident in an instance are supplied by the corresponding generic frame.

Frame Relations

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Reasoning

• Reasoning with a frame KB involves modeling the problem and then reading slots.
• Given a frame KB,
  • Model the problem by instantiating generic-frame instances.
  • As the model is developed, inheritance and attached procedures provide slot fillers.
  • Query the completed model for answers by reading slots.

Local and Global Reasoning

• Local reasoning fills individual-frame slots.
  • Using inheritance and attached procedures.
• Global reasoning maintains global constraints and structures.
  • Using attached procedures mostly.

Frame Extensions

• Frames are easily extensible in any number of ways:
  • Other attached-procedure triggers.
  • Multiple slot fillers.
  • Other slot facets.
  • Metaframes.

Multiple Slot Fillers

• A slot becomes a name, bag pair.
  • The bag (or set, possibly) is usually homogeneous.
• A multi-filler :isa slot opens the door for multiple inheritance.

Slot Facets

• Think of the slot itself as a set of key-value pairs.
  • Keys so far: name, value, attached procedure.
• Each key-value pair is a slot facet.
• It may be useful to define other slot facets.
  • permissible value types, access permissions, cardinality constraints, and so on.

Metaframes

• An individual frame is an instance of a generic frame.
• What is a generic frame an instance of?
  • One answer is “nothing.”
• A Metaframe serves as a model for generic frames.
  • The metaframe determines the structure and behavior of generic frames.
  • The :isa slot determines fillers.

Summary

References

• A Framework for Representing Knowledge by Marvin Minsky in Mind Design, MIT Press, 1981.
• Object-Oriented Representations (Chapter 8) in Knowledge Representation and Reasoning by Ronald Brachman and Hector Levesque, Morgan Kaufmann, 2004.
• Frames and Scripts (Chapter C7) in The Handbook of Artificial Intelligence, vol. 1, by Avron Barr and Edward Feigenbaum, William Kaufmann, 1981.

Credits

• wedding party by hirotomo t under a Creative Commons BY SA license.
• Tea Ceremony @ Jikoin Temple by Hideyuki Kamon under a Creative Commons BY SA license.

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This page last modified on 2011 October 9.