TITLE: ParaMor and Morpho Challenge 2008

Christian Monson, Jaime Carbonell, Alon Lavie, Lori Levin
Language Technologies Institute, Carnegie Mellon University

ParaMor, our unsupervised morphology induction system performed well at Morpho Challenge 2008. When ParaMor's morphological analyses, which specialize at identifying inflectional morphology, are added to the analyses from the general purpose unsupervised morphology induction system, Morfessor, the combined system identifies the morphemes of all five Challenge languages at recall scores higher than those of any other system which competed in Morpho Challenge. In Turkish, for example, the recall of the ParaMor-Morfessor system, at 52.1%, is twice that of the next highest system that participated. These strong recall scores lead to F1 values for morpheme identification as high as or higher than those of any competing system for all the competition languages but English. Of the three language tracks of the task-based information retrieval (IR) evaluation of Morpho Challenge, the combined ParaMor-Morfessor system placed first at average precision in the English and German tracks. And in the German and Finnish tracks of the IR task, the ParaMor-Morfessor system outperformed the hand-built stemming package, Snowball.