One lexeme, many classes: Inflection class systems as lattices

This paper discusses the nature of inflection classes (ICs) and provides a fully im-plemented methodology to conduct typological investigations into their structure.ICs (conjugations or declensions) are sets of lexemes which inflect similarly. Theyare often described as partitioning the set of lexemes, but similarities across classeslead some authors to favor hierarchical descriptions. While some formalisms allowfor multiple inheritance, where one class takes after two or more others, it is usuallytaken as an exceptional situation.I submit that the structure of ICs is a typological property of inflectional systems.As a result, ICs are best modelled as semi-lattices, which by design capture non-canonical phenomena. I show how these monotonous multiple inheritance hierar-chies can be inferred automatically from raw paradigms using alternation patternsand formal concept analysis. Using quantitative measures of canonicity, I comparesix inflectional systems and show that multiple inheritance is in fact pervasiveacross inflectional systems.