# Promising regions in optimization

I have investigated the literature, but I could not find proper explanations. As we know, (meta-)heuristics try to explore promising regions of optimality. The regions are then exploited.

What is the definition of the promising regions in (meta-)heuristic optimization? How can we determine whether the algorithm is in the promising region or not, especially for the problems with unknown optima?

My idea is only that if the algorithm shows continuous improvement, we can say that the region is found. But I am not sure if my idea is totally correct.

• a region is promising if the objective function is decreasing in this area (if you are minimizing). As an analogy, if you are looking for the lowest point in a mountain range, a valley is a promising area. Commented Oct 21, 2021 at 6:55
• But the same definition can be applicable to the condition of local minima(LM): the algorithm converges to a point, which is LM, that is, the fitness value decreases, but it can get stuck in the LM. If we do not know what the optimal value is, we can consider the candidate solution of the algorithm in the LM as the optimal, but the fact is that this is not a promising region. Because both when the optimal solution is reached and when the LM is trapped, the fitness function will not decrease further. So I think we need more than the term "decreasing" for the explanation.
– YcK
Commented Oct 21, 2021 at 7:23
• Well, thats what meta-heuristics are all about: finding promising regions but not getting stuck there. Commented Oct 21, 2021 at 8:11

¹by some I mean it doesn't have to be close with regards to $$\|\cdot\|_2$$ or a similar metric as the crossover example shows
²Assume we minimize $$f(x,y)=g(x)+h(y)$$ if $$x_1,y_1$$ and $$x_2,y_2$$ are good but $$g(x_1) but $$h(y_1)>h(y_2)$$ then $$x_1,y_2$$ is going to be better. In practice this separability is not known by evolutionary algorithm but if $$x_1,y_1$$ and $$x_2,y_2$$ stay successful in the next generation because the worse $$x_2,y_1$$ was generated there is again a 50% chance of $$x_1,y_2$$ being generated.