* More Puzzle Solving

A*

• Super-cool search technique

• Not too hard to implement

Better Search In Sliding Tile Puzzles

• See the course notes on Sliding Tile Puzzles

• http://github.com/pdx-cs-ai/slider

• Brute-force methods don't help much for 15-puzzle

• Heuristic search using A* gets there

Debugging AI

• 5-hour epic debugging session

• Rewrote DFS because Python hates recursion

• Fixed a bunch of bugs

• Getting DFID right is tricky

• Techniques

  • Testing is key

  • Understanding invariants is key

  • Never gonna be sure

Another Heuristic

• Let's add "human-search" to slider.py

• Does looser heuristic really hurt A*?