Page 103 - DCAP506_ARTIFICIAL_INTELLIGENCE

Unit 7: Symbolic Reasoning under Uncertainty

 In Default logic any non-monotonic expressions are rules of inference rather than Notes
expressions.

 Circumscription is a rule of speculation that permits you to come to the conclusion that
the objects you can demonstrate that posses some property, p, are actually all the objects
that posses that property.

 A multiplicity of Truth Maintenance Systems (TMS) have been generated as a means of
executing Non-Monotonic Reasoning Systems.

7.7 Keywords

Circumscription: Circumscription is a rule of speculation that permits you to come to the
conclusion that the objects you can demonstrate that posses some property, p, are actually all the
objects that posses that property.
Default Logic: In Default logic any non-monotonic expressions are rules of inference rather than
expressions.

Default Reasoning: Default reasoning is a very general from of non-monotonic reasoning where
we want to sketch conclusion based on what is most probable to be correct.
Monotonic Reasoning: In monotonic reasoning if we expand at set of axioms we cannot
withdraw any present declarations or axioms.
Non-Monotonic Logic: Non-Monotonic Logic is fundamentally an extension of first-order
predicate logic to comprise a modal operator, M.

7.8 Review Questions

1. Make distinction between formal reasoning and procedural reasoning.
2. Discuss the factors with which Uncertain Reasoning deals with.
3. What is Non-Monotonic Reasoning? Give examples.

4. Identify the approaches used to perform default reasoning.
5. What is default logic?
6. What does Circumscription signify? Illustrate.
7. Illustrate how Circumscription deals with default reasoning.
8. What are Truth Maintenance Systems (TMSs)? Explicate its various types.

9. Consider the problem of deciding which clothes to wear using knowledge such as:
(a) Wear casual clothes unless they are not clean or important meeting occurs today.
(b) Wear a Sweater if it is cold.

(c) The winter is usually cold.
(d) Wear shorts if it’s warm.
(e) The summer is usually warm.
(i) Construct a JTMS network to symbolize these facts.
(ii) Try to solve the problem In winter do I wear shorts?
(iii) Answer the question What shall I wear today (You may assume that the system
knows the time of year).

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