Language and Complexity
William S-Y.Wang, City University of Hong Kong

Recent years have seen two streams of research on systems which have important implications for each other. One stream is characterized by a strong interest in complexity from a variety of disciplines, as discussed in the popular book by M.Waldrop. A core idea of this research is how global complexity can result from numerous local interactions, among physical elements or biological or social agents. The complexification is often simulated on computer, and can sometimes be represented mathematically, often in the form of differential equations.

Languages are clearly complex systems, which are dynamic and adaptive. However, until recently the prevailing ideology has been that all languages are equally complex, regardless of the type of culture these languages serve. Creole languages have now provided counter-examples where the systems are obviously simpler, leading to the hypothesis that complexification is a characteristic of older languages which have accumulated largely nonfunctional features through their histories.

While attempting to bring these two streams together, I will explore briefly the application of ideas from complexity theory to language evolution. The emergence of the lexicon can be simulated by simply assuming that our ancestors had a strong tendency to imitate each other. While the number of words in a language may continue to increase, we find that there is a ceiling in the number that an author actually uses in his writings. The relevant parameters are the size of the community, the number of phonetic signals they produce and distinguish, and the number of messages they need to communicate. The formation of phonological systems can also be simulated by several reasonable assumptions. The linguistic simulations often bring out sharp phase transitions, similarly observed in some other systems when they complexify. I will raise questions on how phenomena such as phase transitions may bring about qualitative changes in the linguistic system. I will also discuss universal features such as homophony in the lexicon and ambiguity in the syntax as possible consequences of complexification.


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