Highly optimized tolerance
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In applied mathematics, highly optimized tolerance (HOT) is a method of generating power law behavior in systems by including a global optimization principle. It was developed by Jean M. Carlson in the early 2000s. For some systems that display a characteristic scale, a global optimization term could potentially be added that would then yield power law behavior. It has been used to generate and describe internet-like graphs, forest fire models and may also apply to biological systems.
The following is taken from Sornette's book.
Consider a random variable, , that takes on values with probability . Furthmore, lets assume for another parameter
for some fixed . We then want to minimize
subject to the constraint
Using Lagrange multipliers, this gives
giving us a power law. The global optimization of minimizing the energy along with the power law dependence between and gives us a power law distribution in probability.
- Carlson, J. M.; Doyle, John (August 1999), "Highly optimized tolerance: A mechanism for power laws in designed systems", Physical Review E, 60 (2): 1412–1427, arXiv:cond-mat/9812127, Bibcode:1999PhRvE..60.1412C, doi:10.1103/PhysRevE.60.1412.
- Carlson, J. M.; Doyle, John (March 2000), "Highly Optimized Tolerance: Robustness and Design in Complex Systems" (PDF), Physical Review Letters, 84 (11): 2529–2532, Bibcode:2000PhRvL..84.2529C, doi:10.1103/PhysRevLett.84.2529.
- Doyle, John; Carlson, J. M. (June 2000), "Power Laws, Highly Optimized Tolerance, and Generalized Source Coding" (PDF), Physical Review Letters, 84 (24): 5656–5659, Bibcode:2000PhRvL..84.5656D, doi:10.1103/PhysRevLett.84.5656, PMID 10991018.
- Greene, Katie (2005), "Untangling a web: The internet gets a new look", Science News, 168 (15): 230, doi:10.2307/4016836, JSTOR 4016836.
- Li, Lun; Alderson, David; Doyle, John C.; Willinger, Walter (2005), "Towards a theory of scale-free graphs: definition, properties, and implications", Internet Mathematics, 2 (4): 431–523, arXiv:cond-mat/0501169, doi:10.1080/15427951.2005.10129111, MR 2241756.
- Robert, Carl; Carlson, J. M.; Doyle, John (April 2001), "Highly optimized tolerance in epidemic models incorporating local optimization and regrowth" (PDF), Physical Review E, 63 (5): 056122, Bibcode:2001PhRvE..63e6122R, doi:10.1103/PhysRevE.63.056122.
- Sornette, Didier (2000), Critical Phenomena in Natural Sciences: Chaos, Fractals, Selforganization and Disorder: Concepts and Tools, Springer Series in Synergetics, Berlin: Springer-Verlag, doi:10.1007/978-3-662-04174-1, ISBN 3-540-67462-4, MR 1782504.
- Zhou, Tong; Carlson, J. M. (2000), "Dynamics and changing environments in highly optimized tolerance", Physical Review E, 62 (3): 3197–3204, Bibcode:2000PhRvE..62.3197Z, doi:10.1103/PhysRevE.62.3197.
- Zhou, Tong; Carlson, J. M.; Doyle, John (2002), "Mutation, specialization, and hypersensitivity in highly optimized tolerance", Proceedings of the National Academy of Sciences, 99 (4): 2049–2054, Bibcode:2002PNAS...99.2049Z, doi:10.1073/pnas.261714399, PMC 122317, PMID 11842230.
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