Valence-changing morphology via lexical rule composition

I describe an analysis of valence-changing verbal morphology implemented as a library extending the LinGO Grammar Matrix customization system. This analysis is based on decomposition of these operations into rule components, which in turn are expressed as lexical rule supertypes that implement specific, isolatable constraints. I also show how common variations of these constraints can be abstracted and parameterized by their axes of variation. I then demonstrate how these constraints can be recomposed in various combinations to provide broad coverage of the typological variation of valence change found in the world’s languages. I evaluate the coverage of this library on five held-out world languages that exhibit these phenomena, achieving 79% coverage and 2% overgeneration.