机器学习
遗传算法（GAS）天生就适合并行实现，并且已经探索了多种并行化方法。
粗粒度并行化方法将种群细分为一些不同的个体组，这些组被称为**“局部种群（demes）”。每个局部种群被分配给一个不同的计算节点，并在每个节点上执行标准的遗传算法搜索。局部种群之间的通信和交叉授粉（cross-fertilization）比局部种群内部发生的频率要低。局部种群之间的转移通过“迁移（migration）”过程进行，其中来自一个局部种群的个体被复制或转移到其他局部种群。这个过程模仿了生物物种物理分离的亚种群之间可能发生的交叉授粉。这种方法的一个好处是，它减少了非并行遗传算法中经常遇到的拥挤问题**——在这种情况下，系统由于早期出现的一种基因型而陷入局部最优，这种基因型最终会主导整个种群。Tanese (1989) 和 Cohoon 等人 (1987) 描述了粗粒度并行遗传算法的例子。
与粗粒度并行实现相反，细粒度并行实现通常为种群中的每个个体分配一个处理器。然后，重组发生在相邻个体之间。目前已经提出了几种不同类型的邻域，从平面网格到环面（torus）。Spiessens 和 Manderick (1991) 描述了这类系统的例子。Stender (1993) 汇编了关于并行遗传算法的论文集。
GAS are naturally suited to parallel implementation, and a number of approaches to
parallelization have been explored. Coarse grain approaches to parallelization subdivide the population
into somewhat distinct groups of individuals, called demes. Each deme is assigned to a different
computational node, and a standard GA search is performed at each node. Communication and cross-
fertilization between demes occurs on a less frequent basis than within demes. Transfer between
demes occurs by a migration process, in which individuals from one deme are copied or transferred to
other demes. This process is modeled after the kind of cross-fertilization that might occur between
physically separated subpopulations of biological species. One benefit of such approaches is that it
reduces the crowding problem often encountered in nonparallel GAS, in which the system falls into a
local optimum due to the early appearance of a genotype that comes to dominate the entire
population. Examples of coarse-grained parallel GAS are described by Tanese (1989) and by Cohoon et
al. (1987).
In contrast to coarse-grained parallel implementations of GAS, fine-grained implementations
typically assign one processor per individual in the population. Recombination then takes place among
neighboring individuals. Several different types of neighborhoods have been proposed, ranging from
planar grid to torus. Examples of such systems are described by Spiessens and Manderick (1991). An
edited collection of papers on parallel GAS is available in Stender (1993).