Aug 29, 2007
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- What makes a good heuristic?
        - h(n) = 0 for all goal nodes n
	- never underestimate the actual cost

- Other additional things we can ask for
        - h(n) should satisfy triangle inequality
                - h(n) <= c(n,n') + h(n')

- Consistent heuristics
        - those that satisfy triangle inequality

- If the heuristic is consistent
	- when finding a node, it would be via the shortest path

- If the heuristic is not consistent AND searching over a graph
	- when finding a node, it would be via the shortest path

- Time complexity of finding optimal solutions
        - If h(n) = h*(n), linear, march on unchallenged
        - If h(n) = 0, exponential
        - If h(n) <= h*(n), still exponential but in
          the difference between the heuristics

- Making A* more efficient
        - mainly w.r.t. space complexity
        - Just as BFS:DFID, we get  A*:IDA*
        - increase trees, not by depth but by f()