Language Learning Dynamics: Coexistence and Selection of Grammars Valery Tereshko School of Computing, University of Paisley, Paisley PA1 2BE, Scotland valery.tereshko@paisley.ac.uk http://cis.paisley.ac.uk/tere-ci0/ Abstract. Language learning dynamics is modelled by an ensemble of individuals consisting of the grammar carriers and the learners. Increas- ing the system population size results into the transition from the indi- vidual to the collective mode of learning. At low communication level, different grammars coexist in their own survival niches. Enhancement of the communication level in purely collective mode, when all individuals are the part of general communication network, leads to the selection of the fittest grammar. Adding the individual mode of learning results into the formation of the quasigrammar, with the dominant grammar prevailing over the set of coexisting grammars. 1 Introduction A community of language users collectively developing a shared communication system can be viewed as the complex adaptive system subjected to a Darwinian evolution [1, 2, 3, 4, 5, 6, 7]. The language users are considered as the interacting agents. The central question is the phenomenon of spontaneous emergence of order in the ensembles of these agents. This order can be static or dynamic, i.e. represents stationary patterns or synchronized motions respectively, and most importantly, it appears without imposing any centralized control. Applying to a language, children are known to develop the grammatical competence by inter- actions with people, without any formal training [8]. This can be viewed as one of examples of the order that emerges entirely through individual’s interactions. In this paper, we consider language learning dynamics as a pattern forma- tion phenomenon in a space of all available grammars, the grammar space. All individuals are divided into the grammar carriers, who are already learned and carry a particular grammar, and the learners who are not carry any grammar yet but potentially can learn one and become the grammar carriers themselves. Since the learners can interact with the carriers of different grammars, they can choose between the latter. On the other hand, the grammar carriers are compet- ing for the pool of learners in the attempts to persuade the latter to their own grammars. The similar approach was used to model the molecular evolution [9] and the honey bee colony foraging dynamics [10, 11, 12]. We introduce the individual and the collective (through communication with other individuals) modes of learning. Increasing the population size results into F. Almeida e Costa et al. (Eds.): ECAL 2007, LNAI 4648, pp. 415–424, 2007. c  Springer-Verlag Berlin Heidelberg 2007