Optimal policies for Bayesian olfactory search in turbulent flows
Open accessAbstract
In many practical scenarios, a flying insect must search for the source of an emitted cue which is advected by the atmospheric wind. On the macroscopic scales of interest, turbulence tends to mix the cue into patches of relatively high concentration over a background of very low concentration, so that the insect will detect the cue only intermittently and cannot rely on chemotactic strategies which simply climb the concentration gradient. In this work we cast this search problem in the language of a partially observable Markov decision process and use the Perseus algorithm to compute strategies that are near-optimal with respect to the arrival time. We test the computed strategies on a large two-dimensional grid, present the resulting trajectories and arrival time statistics, and compare these to the corresponding results for several heuristic strategies, including (space-aware) infotaxis, Thompson sampling, and QMDP. We find that the near-optimal policy found by our implementation of Perseus outperforms all heuristics we test by several measures. We use the near-optimal policy to study how the search difficulty depends on the starting location. We also discuss the choice of initial belief and the robustness of the policies to changes in the environment. Finally, we present a detailed and pedagogical discussion about the implementation of the Perseus algorithm, including the benefits-and pitfalls-of employing a reward-shaping function.
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By employing Pontryagin's minimum principle on the probability density function space, the solution satisfying the optimality condition δJ/δu = 0 is given by Eq. (S4).
“By employing Pontryagin's minimum principle on the probability density function space [1-9], the solution that satisfies the optimality condition δ ˜ J/δ ˜ u = 0 is given by”
From Theoretical Analysis of Resource-Induced Phase Transitions in Estimation Strategies (2026) · cites this paper as [6]
The citation is attached to the use of Pontryagin’s minimum principle on probability-density-function space, not specifically to the citing paper’s Eq. (S4). The cited paper’s Methods (POMDP setup and POMDP solution; page unavailable) describe a Bellman equation and the Perseus value-iteration algorithm. Searches for Pontryagin’s principle and the stated variational optimality condition found no passage addressing that method. (LLM, conf=0.76)
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- Authors
- Heinonen, R. A., Biferale, L., Celani, A., & Vergassola, M.
- Affiliations
- University of Rome Tor Vergata (IT)
- The Abdus Salam International Centre for Theoretical Physics (ICTP) (IT)
- Centre National de la Recherche Scientifique (FR)
- Venue
- Physical Review E
- Publisher
- American Physical Society (APS)
- Published
- 2023-05-16
- Volume
- 107
- Issue
- 5
- Pages
- 055105-055105
- ISSN
- 2470-0045 (ISSN-L)
- 2470-0053
- PMC
- PMC12165250
- OpenAlex
- W4376640537
- Cited by
- 19
- References
- 51
- Citations by year
- 2026: 5 · 2025: 7 · 2024: 5 · 2023: 2
- FWCI
- 3.77
- Type
- journal article
- Language
- en
- Open access
- green
- www.ncbi.nlm.nih.gov
- Locations
- Physical review. E (publishedVersion)
- PubMed (publishedVersion)
- Europe PMC (PubMed Central) (acceptedVersion)
- PubMed Central (acceptedVersion)
- arXiv (Cornell University) (submittedVersion)
- HAL (submittedVersion, other-oa)
- Cineca Institutional Research Information System (Tor Vergata University) (submittedVersion)
- Institutional Research Information System University of Turin (University of Turin) (submittedVersion)
- arXiv (Cornell University)
- Funders
- European Research Council (882340)
- Horizon 2020 (882340)
- H2020 Marie Skłodowska-Curie Actions (956457)
- Topics
- Life Sciences › Agricultural and Biological Sciences › Insect Science › Insect Pheromone Research and Control
- Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Diffusion and Search Dynamics
- Physical Sciences › Computer Science › Artificial Intelligence › Reinforcement Learning in Robotics
- Keywords
- olfactory search, insect navigation, turbulent advection, partially observable Markov decision processes, infotaxis, Thompson sampling, reward shaping, time of arrival, initial beliefs, search difficulty
- MeSH terms
- Algorithms, Animals, Bayes Theorem, Insecta, Smell, Policy
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