CS44 W00: Lecture 11

Topics:

  1. Introduction to Knowledge Representation
  2. Propositional Calculus

Introduction to Knowledge Representation

  1. trade-off between expressiveness and efficiency
  2. representations of blocks world
  3. knowledge base
  4. a knowledge-based agent can be described at three levels (knowledge level, logical level, and implementation level)
  5. syntax and semantics
  6. sound inference systems, complete inference procedures

Propositional Calculus

  1. propositional calculus symbols, atomic symbols, sentences
  2. e.g., symbol P may denote "it is raining"
  3. interpretation of a set of propositions: the truth value assignment to each propositional symbol
  4. truth tables
  5. equivalent expressions: have the same value under all truth value assignments
  6. propositional calculus equivalences
  7. validity and satisfiability of a sentence
  8. patterns of inference, inference rules
    1. modus ponens
    2. and-elimination
    3. and-introduction
    4. or-introduction
    5. double negation elimination
    6. unit resolution
    7. resolution
  9. Monotonicity property: A logic is monotonic if when we add new sentences to the Knowledge Base (KB) all sentences entailed by the original KB are still entailed by the new larger KB
  10. Horn sentences
  11. Problems of propositional calculus (no variables, no access to individual components of assertions, no quantifiers)

Slides

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