Phrase Structure and Ancient Anatolian languages Methodology and challenges for a Luwian syntactic annotation
Authors: Federico Giusfredi (Università di Verona, 2015)
Topic: Latin Resources

Abstract
For the Marie Skłodowska Curie (MSCA) funded project “SLUW – A computer aided study of the (morpho)syntax of Luwian” a collection of phrase structure trees from the Luwian corpus is currently being prepared. Luwian is a language belonging to the Anatolian branch of Indo-European; its structures are different from those of English and the language itself is partly obscure. The present paper will describe some special needs, open challenges and methodologies relevant for the annotation of phrasestructure of Luwian.

Introduction
Annotating a dead language, especially if lacunae and obscure sequences occur frequently in the corpus, is a challenging task. In the case of phrase-structure trees, those challenges complicate the usual issues represented by “trapping” (an element nested within the boundaries of a phrase it does not belong to) and standard discontinuous phrases. The language under investigation is Luwian, an ancient member of the Anatolian branch of Indo-European, the second largest one after Hittite by number of documents. It was written using two different writing systems (the cuneiform script and the Anatolian hieroglyphs). The attestations cover a time span of almost one millennium, between the 16th and the 8th centuries BCE (cf. Melchert, 2003). Syntactically speaking, it features a rather strict SOV word-order as far as some classes of constituents are concerned (Wackernagel particles, inflected verb at the end, left-branching of genitives and attributes); while a few elements can move with relative freedom (for instance adverbs, indirect case NPs and PPs with respect to the position of a direct object). The final goal of the SLUW project, a Horizon2020 MSCA funded two-year research plan hosted by the University of Verona (2015-2017) is to produce a general study of the syntax (and morpho-syntax) of the language; in order to do so, a significant selection of sentences (about 30% to 50% of the corpus) will be collected and annotated in order to produce phrase-structure trees that will help highlight syntactic patterns. Theory-free phrase structure annotation is more suitable than Universal Dependencies for this kind of approach, as the boundaries of linear and non-linear phrases as well as their canonical or non-canonical position within the sentence are more easily identified. Since the structure of Luwian is very different from the one of English – Anatolian languages had peculiar features that must be accounted for – the starting point for the development of a POS tagset, the “label-tag” context-sensitive system of the Penn Treebank II, requires to be modified in order to better match the object of study.

Conclusion
The creation of phrase-structure trees for ancient languages with structural peculiarities that make them very different from modern ones may require specific modifications to the usual parsing tagsets. Such modifications may occur both on the phrase and on the word levels. In order to minimize the challenges and maximize flexibility, a context-sensitive syntax with both labels and functional tags is more suitable than a rigid one; for instance functional markers for case inflection may apply to several different categories of labels (all nouns, adjectives and pronouns). As far as discontinuous phrases are concerned, in the analysis of dead languages they may be natural linguistic phenomena, but they may also be the result of either poor text preservation or limited understanding of given segments. In order to avoid inaccurate nesting, a system of coindexing appears to be the most advisable solution to guarantee a good degree of accuracy in the linguistic representation and a regular treatment of the linearity issues.