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> That's a classic problem (exploration vs exploitation, aka coverage vs convergence) in optimisation problems. The nicest approach to exploration/exploitation
by chriswarbo 12y ago
> That's a classic problem (exploration vs exploitation, aka coverage vs convergence) in optimisation problems.
The nicest approach to exploration/exploitation I've seen for simulated annealing is to run two searches side-by-side. Their relative "temperatures" (ie. probability of accepting a worse solution) depends on their relative fitness: if both are the same fitness, both have the same temperature; if one has higher fitness than the other, its temperature lowers (so it can "focus" on that high-fitness region) whilst the other's temperature raises (so it can "spread out" to find higher-fitness regions).
Also, regarding the No Free Lunch Theorems, I don't give them much thought since they don't take the computational complexity of the problem into account. They say that every search algorithm, when averaged over all problems, achieves total performance that's the same as random search. The real world doesn't contain all problems; in particular, we care more about (computationally) simple problems than unrealisitically-complex ones. Worrying about NFL for search is like worrying about adversaries with infinite computing power in crypto; yes your algorithm will be weak against such an attacker, but it's unrealistic to care about.
- jacques_chester 12y agoFor me the two lessons of the No Free Lunch Theorem are: 1. Stop trying to prove that your solution is the "best overall" 2. Hooray, we can pick and choose our tools.