翻訳と辞書 Words near each other ・ Biogenesis baseball scandal ・ Biogenesis of lysosome-related organelles complex 1 ・ Biogenetic structuralism ・ Biogenic amine ・ Biogenic amine receptor ・ Biogenic silica ・ Biogenic substance ・ Biogenic sulfide corrosion ・ Biogeochemical cycle ・ Biogeochemistry ・ Biogeoclimatic zones of British Columbia ・ Biogeographic classification of India ・ Biogeography ・ Biogeography of Deep-Water Chemosynthetic Ecosystems ・ Biogeography of gastropods ・ Biogeography-based optimization ・ Biogeology ・ Biogeomorphology ・ Biogeophysics ・ Bioggio ・ Bioggio Molinazzo railway station ・ Bioggio railway station ・ BioGift ・ Bioglass ・ Bioglio ・ Biogno ・ BioGnost ・ Biograci ・ Biograd (disambiguation) ・ Biograd na Moru Dictionary Lists mini英和辞書 mini和英辞書 Webster 1913 Latin-English FOLDOC Wikipedia English ウィキペディア

翻訳と辞書　辞書検索 [ 開発暫定版 ] スポンサード リンク Biogeography-based optimization ： ウィキペディア英語版 Biogeography-based optimization Biogeography-based optimization (BBO) is an evolutionary algorithm (EA) that optimizes a function by stochastically and iteratively improving candidate solutions with regard to a given measure of quality, or fitness function. BBO belongs to the class of metaheuristics since it includes many variations, and since it does not make any assumptions about the problem and can therefore be applied to a wide class of problems. BBO is typically used to optimize multidimensional real-valued functions, but it does not use the gradient of the function, which means that it does not require the function to be differentiable as required by classic optimization methods such as gradient descent and quasi-newton methods. BBO can therefore be used on discontinuous functions. BBO optimizes a problem by maintaining a population of candidate solutions, and creating new candidate solutions by combining existing ones according to a simple formula. In this way the objective function is treated as a black box that merely provides a measure of quality given a candidate solution, and the function's gradient is not needed. Like many EAs, BBO was motivated by a natural process; in particular, BBO was motivated by biogeography, which is the study of the distribution of biological species through time and space.〔 BBO was originally introduced by (Dan Simon ) in 2008.〔 == Underlying principles == Mathematical models of biogeography describe speciation (the evolution of new species), the migration of species (animals, fish, birds, or insects) between islands, and the extinction of species.〔 Islands that are friendly to life are said to have a high habitat suitability index (HSI).〔 Features that correlate with HSI include rainfall, vegetative diversity, topographic diversity, land area, temperature, and others. The features that determine are called suitability index variables (SIVs). In terms of habitability, SIVs are the independent variables and HSI is the dependent variable. Islands with a high HSI can support many species, and islands with a low HSI can support only a few species. Islands with a high HSI have many species that emigrate to nearby habitats because of the large populations and the large numbers of species that they host. Note that emigration from an island with a high HSI does not occur because species ''want'' to leave their home; after all, their home island is an attractive place to live. Emigration occurs because of the accumulation of random effects on a large number of species with large populations. Emigration occurs as animals ride flotsam, swim, fly, or ride the wind to neighboring islands. When a species emigrates from an island, it does not mean that the species completely disappears from its original island; only a few representatives emigrate, so an emigrating species remains present on its original island while at the same time migrating to a neighboring island. However, in BBO it is assumed that emigration from an island results in extinction from that island. This assumption is necessary in BBO because species represent the independent variables of a function, and each island represents a candidate solution to a function optimization problem. Islands with a high HSI not only have a high emigration rate, but they also have a low immigration rate because they already support many species. Species that migrate to such islands will tend to die in spite of the island's high HSI, because there is too much competition for resources from other species. Islands with a low HSI have a high immigration rate because of their low populations. Again, this is not because species ''want'' to immigrate to such islands; after all, these islands are undesirable places to live. The reason that immigration occurs to these islands is because there is a lot of room for additional species. Whether or not the immigrating species can survive in its new home, and for how long, is another question. However, species diversity is correlated with HSI, so when more species arrive at a low HSI island, the island's HSI will tend to increase.〔 The figure on the right illustrates an island migration model.〔 The immigration rate $\backslash lambda$ and the emigration rate $\backslash mu$ are functions of the number of species on the island. The maximum possible immigration rate $I$ occurs when there are zero species on the island. As the number of species increases, the island becomes more crowded, fewer species are able to survive immigration, and the immigration rate decreases. The largest possible number of species that the habitat can support is $S\_$, at which point the immigration rate is zero. If there are no species on the island, then the emigration rate is zero. As the number of species on the island increases, it becomes more crowded, more species representatives are able to leave the island, and the emigration rate increases. When the island contains the largest number of possible species $S\_$, the emigration rate reaches its maximum possible value $E$. In BBO, $\backslash lambda\_k$ is the probability that a given independent variable in the $k$-th candidate solution will be replaced; that is, $\backslash lambda\_k$ is the immigration probability of $x\_k$. If an independent variable is to be replaced, then the emigrating candidate solution is chosen with a probability that is proportional to the emigration probability $\backslash mu\_k$. This is usually performed using roulette wheel selection. :: $$ \text(x_j)\text = \frac for $j=1,\backslash cdots,N$, where $N$ is the number of candidate solutions in the population. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Biogeography-based optimization」の詳細全文を読む スポンサード リンク 翻訳と辞書 : 翻訳のためのインターネットリソース Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.