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heuristics

Heuristic path algorithm (Pohl) completeness


This is a homework question, exactly as follows:

The heuristic path algorithm (Pohl, 1977) is a best-first search in which the evaluation function is f(n) = (2-w)g(n) + wh(n).

For what values of w is this complete?

Here's what I know:

w = 0: f(n)=2g(n) --> Uniform Cost Search, which is complete.

w = 1: f(n)=g(n) + h(n) --> A*, which is complete.

w = 2: f(n)=2h(n) --> greedy Best First Search, which is not complete.

What about all other values of w?

Please don't just give the answer, help me get to the solution.


Solution

  • Interesting thing about "all other values of w" for w>2: They all have the form f(n) = h(n) - g(n) with some constants in front of h and g. What impact, if any, does subtracting the cost have on completeness? Seems you should be able to generalize from there.