First-Order Databases

PSU CS441/541 Lecture 4
October 16, 2000

• Review: HW1
  • Sample Zebra encoding (CSPC, Jónsson 1995)
    • setup
    • encoding
  • Comments on grounding out encoding
• Review: HW2
  • Satisfiability revisited
  • Binary search revisited
  • Pseudocode for DP SAT engine
• First-Order Logic
  • Quantifiers: the general case
    • negation and flipping
    • generalization
    • elimination of exists by Skolemization
    • e.g.: forall h . [big(h) and exists p . house(h, p) implies work(h)]
      • Goal: forall h, p . [big(h) and house(h, p) implies work(h)]
      • Trick: existential negation
  • Logic databases
    • ``normal form'' clauses and Algorithm 8.6.3
    • negated queries
    • querying normal form databases
      • normal form resolution
      • renaming bound variables
      • unification and bindings
  • Search and search control
    • set-of-support and the ramification problem
    • imperative search control
      • e.g. ordered search: static, user-supplied
      • can be very efficient
      • encodes the answer
    • automatic search control
      • e.g. lookahead, general purpose heuristics
      • variable: ``cheapest-first'' (= most-constrained first)
      • value: least-constraining first
      • DFS considered ugly: fancy backtracking
    • metalevel reasoning
• Review: Midterm
  • Lecture 1: Introduction
    • AI: Concept
    • AI: Implementation
    • AI: History
    • Limits of computation
  • Lecture 2: KR
    • KR
      • KR properties
      • Logic as KR
      • Other common AI KRs
    • Logic
      • PROP/PRED/FOL
      • model, interpretation, meaning
      • soundness, completeness
      • entailment, inference
      • standard inference rules
      • Horn clauses
      • resolution
      • why logic matters to AI
  • Lecture 3: Search
    • Classes: game playing, pathfinding, satisfying/satisficing
    • what is NP?
    • blind search: DFS, BFS, ID, IB
    • heuristic search: heuristics, A* pathfinding
    • local search: giving up completeness for efficiency
    • DP and WSAT for Boolean SAT search
  • Lecture 4: First-Order Databases
    • logic databases
    • search control