期刊名称：International Journal of Mathematics and Mathematical Sciences
印刷版ISSN：0161-1712
电子版ISSN：1687-0425
出版年度：1983
卷号：6
DOI：10.1155/S0161171283000356
出版社：Hindawi Publishing Corporation
摘要：It is proved that for a probabilistic context-free language L(G), the population density of a character (terminal symbol) is equal to its relative density
in the words of a sample S from L(G) whenever the production probabilities of the grammar G are estimated by the relative frequencies of the corresponding productions in the sample.
