Cost Based Satisficing Search Considered Harmful

Cushing, William; Benton, J.; Kambhampati, Subbarao

doi:10.48550/arxiv.1103.3687

Cited by 2 publications

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“…Table 1: A* expansions on different problems invited questions about the theoretical underpinnings of precisely why the range of operator costs was causing such a huge problem, and also questions about why the presence of an informed heuristic was not ameliorating the problem. Concurrently with our work, Cushing, Benton, and Kambhampati (2011) extended their previous analysis, discussing examples of domains that exhibit the problematic operator cost ratios. Once again, their theoretical analysis is almost exclusively confined to uniform cost search, and does not consider the mitigating effects an informed heuristic can have, although they speculate that heuristics can help improve the bound, but not asymptotically.…”

Section: Related Workmentioning

confidence: 75%

Cost-Based Heuristic Search Is Sensitive to the Ratio of Operator Costs

Wilt

Ruml

2021

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In many domains, different actions have different costs. In this paper, we show that various kinds of best-first search algorithms are sensitive to the ratio between the lowest and highest operator costs. First, we take common benchmark domains and show that when we increase the ratio of operator costs, the number of node expansions required to find a solution increases. Second, we provide a theoretical analysis showing one reason this phenomenon occurs. We also discuss additional domain features that can cause this increased difficulty. Third, we show that searching using distance-to-go estimates can significantly ameliorate this problem. Our analysis takes an important step toward understanding algorithm performance in the presence of differing costs. This research direction will likely only grow in importance as heuristic search is deployed to solve real-world problems.

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Section: Related Workmentioning

confidence: 75%

Cost-Based Heuristic Search Is Sensitive to the Ratio of Operator Costs

Wilt

Ruml

2021

SOCS

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“…The costbased grid navigation problem, however, does not suffer from a significant increase in search effort and the authors attribute it to size-bounded local minima and the large number of duplicates. 2 To mitigate the negative effect of large operator cost ratio, a number of authors suggest using sizebased search (Cushing, Benton, and Kambhampati 2011;Wilt and Ruml 2011;.…”

Section: A Domain-specific Modelmentioning

confidence: 99%

Cost-Based Heuristics and Node Re-Expansions across the Phase Transition

Cohen

Beck

2021

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Recent work aimed at developing a deeper understanding of suboptimal heuristic search has demonstrated that the use of a cost-based heuristic function in the presence of large operator cost ratio and the decision to allow re-opening of visited nodes can have a significant effect on search effort. In parallel research, phase transitions in problem solubility have proved useful in the study of problem difficulty for many computational problems and have recently been shown to exist in heuristic search problems. In this paper, we show that the impact on search effort associated with a larger operator cost ratio and the number of node re-expansions is concentrated almost entirely in the phase transition region. Combined with previous work connecting local minima in the search space with such behavior, these observations lead us to hypothesize a relationship between the phase transition and the existence of local minima.

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Cost Based Satisficing Search Considered Harmful

Cited by 2 publications

References 0 publications

Cost-Based Heuristic Search Is Sensitive to the Ratio of Operator Costs

Cost-Based Heuristic Search Is Sensitive to the Ratio of Operator Costs

Cost-Based Heuristics and Node Re-Expansions across the Phase Transition

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