Parsing Early N ew H igh G erman: Benefits and limitations of cross-dialectal training (2023)

Abstract: Historical treebanking within the generative framework has gained in popularity. However, there are still many languages and historical periods yet to be represented. For German, a constituency treebank exists for historical Low German, but not Early New High German. We begin to fill this gap by presenting our initial work on the Parsed Corpus of Early New High German (PCENHG). We present the methodological considerations and workflow for the treebank’s annotations and development. Given the limited amount of currently available PCENHG treebank data, we treat it as a low-resource language and leverage a larger, closely related variety—Middle Low German—to build a parser to help facilitate faster post-annotation correction. We present an analysis on annotation speeds and conclude with a small pilot use-case, highlighting potential for future linguistic analyses. In doing so we highlight the value of the treebank’s development for historical linguistic analysis and demonstrate the benefits and challenges of developing a parser using two closely related historical Germanic varieties.

## introduction the most common system for historical treebanks in the generative framework is the penn family of parsed historical corpora. these are valuable resources for analyzing syntactic change and have resulted in an explosion of research in this area, including the annual diachronic generative syntax conference and journal of historical syntax. the germanic family is well-represented (see section 3.1), with the exception of high german (hg). our broader research agenda seeks to fill this gap by creating a parsed corpus of early new high german @xcite @xcite . although there is no penn-style treebank for any stage of hg on which to train a parser foot_0 , there does exist the corpus of historical low german (chlg; @xcite , which we can use as a starting point. the low german (lg) language subsumes northern dialects that preserve proto-germanic *p, *t, and *k, while hg varieties partially or fully reflect the hg consonant shift (@xmath0, @xmath1, @xmath2, etc.) and include all central and southern dialects and modern standard german. despite these phonological differences and the characterization of lg and hg as separate languages, they are highly similar in lexis and syntax @xcite , although this syntactic similarity is questioned by @xcite . we introduce the first stages of the parsed corpus of early new high german, along with the current workflow for developing the treebank and the supporting rationale for our chosen annotation and methodology. we explore a strategy of training a parser on historical texts from the chlg treebank to help facilitate and aid in creating an enhg treebank. in addition to initial parsing experiments to provide basic insights into the effectiveness of a cross-variety parser, we perform a small pilot case study to highlight potential linguistic challenges and use-cases for the treebank. ## dialectal differences: case study of he/er there are several exploratory uses for historical treebanking, predominantly the ability to identify and analyze diachronic changes in syntactic structures. a more computational use is to examine how effectively we can develop parsers that cover a range of historical changes, as well as dialectal variation, in a language. to demonstrate use-cases for both on the pcenhg, we train a parser on a single text and parse the other texts to 1) explore the difficulty in cross-textual parsing given diachronic, dialect, domain, and genre differences and 2) analyze parser outputs of a single, high-frequency function word which has two distinct forms but a single syntactic representation across the different dialects. ## conclusion we have introduced the parsed corpus of early new high german. its introduction and continued development presents an additional resource for research both on diachronic syntax and on parsing. we have begun construction of the treebank by successfully utilizing a treebank from a closely related language to develop a base parsing system that helps speed up the annotation process. we use a cyclical process in which outputs are sent through a workflow that automates various post-correction requirements, before finally being hand-corrected by an expert annotator, with the new gold sentences able to be used to train a new parser. as our gold treebank for enhg continues to grow, we should be able to reduce our dependence on the chlg treebank. however, we have also shown that while there are lexical and some syntactic differences between the texts, higher-level projections still benefit from the mixing since many of the rules are applicable in both varieties, even in the presence of lexical and lower-level syntactic differences, as indicated by the case study of he/er variation. once the parsed corpus of early new high german is complete, we expect to use it to train a model that can parse both middle high german (1050-1350) and modern german (1650-present). this will allow the completion of a parsed corpus of the whole history of hg (as well as providing a source of possible additional data for developing additional ptb-style treebanks of modern standard german). such a timespan and the variation in texts will also allow us to contribute simultaneously to both cross-domain and diachronic parsing research, in particular using a single unified model.