Unifying the Treatment of Preposition-Determiner Contractions in German Universal Dependencies Treebanks

HDT-UD, the largest German UD treebank, as well as the German-LIT treebank, currently do not analyze preposition-determiner contractions such as zum (= zu dem, “to the”) as multi-word tokens, which is inconsistent both with UD guidelines as well as other German UD corpora (GSD and PUD). In this paper, we show that harmonizing corpora with regard to this highly frequent phenomenon using a lookup-table leads to a considerable increase in automatic parsing performance.