Much ado about nothing: A social network model of Russian paradigmatic gaps

Proceedings of the 45th Annual Meeting of the Association of Computational Linguistics, pages 936–943, Prague, Czech Republic, June 2007. c⃝2007 Association for Computational Linguistics Much ado about nothing: A social network model of Russian paradigmatic gaps Robert Daland Andrea D. Sims Janet Pierrehumbert Department of Linguistics Northwestern University 2016 Sheridan Road Evanston, IL 60208 USA r-daland, andrea-sims, jbp@northwestern.edu Abstract A number of Russian verbs lack 1sg non- past forms. These paradigmatic gaps are puzzling because they seemingly contradict the highly productive nature of inflectional systems. We model the persistence and spread of Russian gaps via a multi-agent model with Bayesian learning. We ran three simulations: no grammar learning, learning with arbitrary analogical pressure, and morphophonologically conditioned learning. We compare the results to the attested historical development of the gaps. Contradicting previous accounts, we propose that the persistence of gaps can be explained in the absence of synchronic competition between forms. 1 Introduction Paradigmatic gaps present an interesting challenge for theories of inflectional structure and language learning. Wug tests, analogical change and children’s overextensions of regular patterns demonstrate that inflectional morphology is highly productive. Yet lemmas sometimes have “missing” inflected forms. For example, in Russian the majority of verbs have first person singular (1sg) non-past forms (e.g., posadit’ ‘to plant’, posažu ‘I will plant’), but no 1sg form for a number of similar verbs (e.g., pobedit’ ‘to win’, *pobežu ‘I will win’). The challenge lies in explaining this apparent contradiction. Given the highly produc- tive nature of inflection, why do paradigmatic gaps arise? Why do they persist? One approach explains paradigmatic gaps as a problem in generating an acceptable form. Under this hypothesis, gaps result from irreconcilable conflict between two or more inflectional patterns. For example, Albright (2003) presents an analysis of Spanish verbal gaps based on the Minimal Generalization Learner (Albright and Hayes 2002). In his account, competition between mid-vowel diphthongization (e.g., s[e]ntir ‘to feel’, s[je]nto ‘I feel’) and non-diphthongization (e.g., p[e]dir ‘to ask’, p[i]do ‘I ask’) leads to paradigmatic gaps in lexemes for which the applicability of diphthon- gization has low reliability (e.g., abolir ‘to abolish, *ab[we]lo, *ab[o]lo ‘I abolish’). However, this approach both overpredicts and underpredicts the existence of gaps cross- linguistically. First, it predicts that gaps should occur whenever the analogical forces determining word forms are contradictory and evenly weighted. However, variation between two inflectional patterns seems to more commonly result from such a scenario. Second, the model predicts that if the form-based conflict disappears, the gaps should also disappear. However, in Russian and probably in other languages, gaps persist even after the loss of competing inflectional patterns or other synchronic form-based motivation (Sims 2006). By contrast, our approach operates at the level of inflectional property sets (IPS), or more properly, at the level of inflectional paradigms. We propose that once gaps are established in a language for whatever reason, they persist because learners infer the relative non-use of a given 1 936 combination of stem and IPS.1 Put differently, we hypothesize that speakers possess at least …

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