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| Table 1: Typical Structures and Operators | | Field | Structures | Operators | | Genetics | chromosomes | mutation, recombination, etc. | | | Economic planning | mixes of goods | production activities | | | Control | policies | Bayes's rule, successive approximation, etc. | | | Physiological psychology | cell assemblies | synapse modification | | | | | Game theory | strategies | rules for iterative approximation of optimal strategy | | | Artificial intelligence | programs | "learning" rules |
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by applying all possible operator sequences marks out the limits of the adaptive plan's domain of action. Since a given structure performs differently in different environmentsthe structure is more or less fitit is the adaptive plan's task to produce structures which perform "well" (are fit) in the environment confronting it. "Adaptations" to the environment are persistent properties of the sequence of structures generated by the adaptive plan. |
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A precise statement of the adaptive plan's task serves as a key to uniform treatment. Three major components are associated in the task statement: (1) the environment, E,of the system undergoing adaptation, (2) the adaptive plan, t,whereby the system's structure is modified to effect improvements, (3) a measure, µ, of performance, i.e., the fitness of the structures for the environment. (The formal framework developed in chapter 2 is built around these three components.) The crux of the problem for the plan t is that initially it has incomplete information about which structures are most fit. To reduce this uncertainty the plan must test the performance of different structures in the environment. The "adaptiveness" of the plan enters when different environments cause different sequences of structures to be generated and tested. |
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In more detail and somewhat more formally: A characteristic of the environment can be unknown (from the adaptive plan's point of view) only if alternative outcomes of the plan's tests are allowed for. Each distinct combination of alternatives is a distinct environment E in which the plan may have to act. The set of all possible combinations of alternatives indicates the plan's initial uncertainty about the environment confronting itthe range of environments in which the plan should be able to act. This initial uncertainty about the environment will be formalized by designating a class e of possible environments. The domain of action |
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