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Hill-climbing Search Goal: Optimizing an objective function.

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Presentation on theme: "Hill-climbing Search Goal: Optimizing an objective function."— Presentation transcript:

1 Hill-climbing Search Goal: Optimizing an objective function.
Can be applied to “goal” predicate type of problems. BSAT with objective function number of clauses satisfied. Intuition: Always move to a better state

2 Some Hill-Climbing Algo’s
Start State = empty state or random state or special state Until (no improvement) Steepest Ascent: find best successor OR (greedy): select first improving successor Go to that successor Repeat the above process some number of times (Restarts). Can be done with partial solutions or full solutions.

3 Local (Iterative) Improving
Initial state = full candidate solution Random or “nearest neighbor selection” Greedy hill-climbing: if up, do it if flat, probabilistically decide to accept move Not necessary for homework Otherwise need to limit number of flat moves if down, don’t do it We are gradually expanding the possible moves.

4 TSP Notes Only use “up” moves
It is not necessary to compute the entire tour lengths after an operator applies. Instead compute change in length- most of the path length stays the same. You keep applying the operators until no improvement occurs.

5 Uncross Problem


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