Inferring inflection classes with description length

Abstract

We discuss the notion of an inflection class system, a traditional ingredient of the description of inflection systems of nontrivial complexity. We distinguish systems of microclasses, which partition a set of lexemes in classes with identical behavior, and systems of macroclasses, which group lexemes that are similar enough in a few larger classes. On the basis of the intuition that macroclasses should contribute to a concise description of the system, we propose one algorithmic method for inferring macroclasses from raw inflectional paradigms, based on minimisation of the description length of the system under a given strategy of identifying morphological alternations in paradigms. We then exhibit classifications produced by our implementation on French and European Portuguese conjugation data and argue that they constitute an appropriate systematisation of traditional classifications. To arrive at such a convincing systematisation, it was crucial for us to use a local approach to inflection class similarity (based on pairwise comparisons of paradigm cells) rather than a global approach (based on the simultaneous comparison of all cells). We conclude that it is indeed possible to infer inflectional macroclasses objectively.

The Paradigm Discovery Problem

“…To gauge the quality of a candidate paradigm, we first identify its base and exponents. Following Beniamine et al (2018), we define π's base, b π , as the longest common subsequence shared by all forms in π. 56 For each form f in π, we define the exponent x f as the subsequences of f that remain after removing b π , i.e., x f is a tuple of affixes.…”

“…A detailed analysis of Latin nouns (also analyzed by Stump and Finkel (2015) and Beniamine et al (2018)) reveals challenges for our system. Table 5 shows the inflectional paradigms for three Latin nouns exemplifying different inflection classes, which are mentioned throughout the analysis.…”

Overabundance and inflectional classification: Quantitative evidence from Czech

“…Inflectional systems of any complexity exhibit differential inflectional behavior, where lexemes of the same part of speech use different marking strategies to contrast the forms filling cells of their inflectional paradigm. Systems of inflection classes are the tool of choice to explicate such variability, and recent research has highlighted how such systems are organized (Corbett & Fraser 1993;Dressler & Thornton 1996;Brown & Hippisley 2012;Beniamine, Bonami & Sagot 2017;Beniamine 2021) and how they tend to be partially but not fully motivated by other lexical properties (Aronoff 1994;Baayen & Moscoso del Prado Martín 2005;Guzmán Naranjo 2019). Overabundance may interact with 1 Thornton's typology is stated in terms of canonical criteria (Corbett 2007;Brown, Chumakina & Corbett 2013), and focuses on endpoints of the dimensions rather than describing the dimensions directly.…”

Frugal Paradigm Completion

“…Paradigm completion from one source is typically non-deterministic due to multiple inflection classes realizing different exponents in some cells, e.g., suffixing +ed generates the past tense for WALK, but not for SING or FLY which are members of different classes. Hence, many works discuss paradigm completion in the context of (implicit) inflection class disambiguation (Ackerman et al, 2009;Montermini and Bonami, 2013;Beniamine et al, 2018). Finkel and Stump (2007) propose three approaches to select the fewest sources required to deterministically identify class.…”