Exam P6 Flashcards
What are the main advantages of representing knowledge in Frame Systems compared to Logics?
- All known knowledge about a given concept is grouped in its corresponding frame
- Combines declarative and procedural knowledge
- For humans, it’s more natural to represent k, in classes and instances with slots (and facets) than in predicates, function and constants.
- Inheritance is a natural form of reasoning
- Inheritance is an efficient reasoning mechanism
Frame systems combine declarative and procedural knowledge (classes and instances with procedural attachment). Explain this combination and its advantages over a purely declarative approach in logic.
This combinations offers advantages over over purely declarative logic by providing a more natural human-like representation, enabling efficient reasoning like inheritance, and allowing for the direct integration of behavior and dynamic computations within the knowledge structure
In general, inheritance is presented as an efficient reasoning mechanism. Discuss the conditions under which this efficiency might hold.
Inheritance is an efficient reasoning mechanism when there are strict hierarchies, and a well-organized knowledge base where relevant properties are appropriately placed
What are some of the weaknesses of Frame Systems?
Frame systems, in general, lack a formal semantics
Declarative knowledge:
- Pat Hayes’ translational approach: Problem with default values
- In KEE, no such problem, proposed later, used Reiter’s Default Logic
Reasoning:
- Procedural attachments, impossible to provide a semantics, the KB changes and the rational is based on the code and not in the World
Pat Hayes’s translational approach encountered a problem with Default values. Briefly explain this problem in the context of frames and logics.
Pat Haye’s attempt to translate frame systems into FOL struggled with default values. The problem was that in frames, default values could be overridden by more specific information. A purely logical translation could not easily capture the non-monotonic nature of default value inheritance and overriding in frame systems, as standard logic lacks the mechanism to handle exceptions. The issue highlighted the need for non-monotonic logic.
