General Problem Solver

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General Problem Solver

• Leslie Price
• February 26, 2008

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What is it?

• Developed by Alan Newell and Herb Simon
• Problem solving research
• Computer simulation of human problem solving
• Called General Problem Solver because could
  solve a wide range of problems

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How does it solve problems?

• Applies means-end analysis
• Useful analogy for how humans may solve problems
• Represents the problem and the goal
• Identifies subgoals and operators that will
  produce the goal
• Plans within plans
• Creates rules to solve problems
• Applied to several logic problems
• Tower of Hanoi, Missionary-Cannibal problem,
  three coins puzzle, water jug task, etc.

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Tower of Hanoi

• Three pegs, disks of different sizes
• Disks stacked in order of size
• Move stack to another peg
• Only move one at a time
• Cannot place larger disk on top of smaller disk

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Rules Created for the Tower of Hanoi Problem

• IF the destination peg is clear and the largest
  disk is free, THEN move the largest disk to the
  destination peg
• IF the largest disk is not free, THEN set up a
  subgoal that will free it
• IF the subgoal of freeing the largest disk has
  been set up and a smaller disk is on that disk,
  THEN move the smaller disk to the stack peg.

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Testing the GPS

• Newell, Simon, and other researchers have
  compared the GPS to humans abilities
• Participants in studies spoke out loud when
  solving logic problems
• Significant relationship between participants
  steps and steps the GPS uses

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Limitations of GPS

• Sometimes it deviates from strategies people use
  to solve problems
• Humans use the hill-climbing strategy
• GPS does not use this strategy
• GPS may fail to solve the problem because it
  applies the means-end heuristic too strictly