Classifying Divergences in Cross-lingual AMR Pairs (2021)

Abstract: Translation divergences are varied and widespread, challenging approaches that rely on parallel text. To annotate translation divergences, we propose a schema grounded in the Abstract Meaning Representation (AMR), a sentence-level semantic framework instantiated for a number of languages. By comparing parallel AMR graphs, we can identify specific points of divergence. Each divergence is labeled with both a type and a cause. We release a small corpus of annotated English-Spanish data, and analyze the annotations in our corpus.

## introduction a variety of factors come into play in translating from one language into another @xcite . the resulting parallel texts are not always completely equivalent in meaning. differences, or divergences, between the source and target may reflect lexical or grammatical differences between the two languages, stylistic considerations, or simply the translator's preference for idiomatic phrasing. identifying translation divergences may enable more nuanced use of parallel text in applications; for example, it has been shown that translation divergences have a measurable impact on machine translation @xcite . this information on the types and causes of divergence enables these parallel texts to be more fully utilized in crosslingual natural language processing tasks. specifically, different types of semantic divergences impact the performance of neural machine translation systems differently @xcite , which motivates work to categorize and describe divergences in parallel texts. taking advantage of the fact that abstract meaning representation (amr) @xcite resources and tools have been developed for a variety of languages ( §2.3) and given the usefulness of amr for downstream multilingual tasks such as machine translation @xcite , we signal the need for categorization and detection of divergences in crosslingual amr pairs. the structure of an amr reflects the semantic relations of the sentence, so structural divergences (a difference in the structure of an amr graph, whether it be the label or role) between multilingual amr pairs serve as a reflection of semantic differences between a sentence and its translation. we develop and present a categorization schema to identify both the type and the cause of the divergence as being due to semantic divergence, annotation divergence, or syntactic divergence; this schema annotates both the type and cause of a structural divergence, to (1) make the data more adaptable to cross-lingual nlp applications, (2) identify non-literal translations, (3) make amr more crosslinguistically consistent @xcite , and (4) investigate the ways in which annotation, semantics, and syntax play a role in cross-lingual amr parsing @xcite . we then annotate a set of 50 parallel english-spanish amrs annotations from the little prince (migueles-abraira, 2017) using our divergence schema and make these annotations available online. using this small set of gold annotated data, we are able to explore the comprehensiveness and meaningfulness of this annotation schema. our contributions include: ## cross-lingual amr divergence annotation schema we develop a categorization schema to be able to identify with granularity the type of structural cause of divergence semantic divergence annotation divergence syntactic divergence figure 3: causes of structural divergence. if an amr pair has a structural divergence, meaning there is some difference in the way that the two amrs are structured, there must be both a type of divergence (figure 2 ) and a cause for the divergence (figure 3 ). ## annotated corpus in order to demonstrate the scope, effectiveness and use of this annotation schema, we decide to annotate a small corpus of english-spanish sentences within the domain of literary works. we use a set of 50 english-spanish amr pairs, representing parallel sentences from the little prince @xcite . the work from which these 50 english-spanish amr pairs are derived also presents relevant linguistic issues hindering spanish amr annotation: np ellipses, third person possessive pronouns, third person clitic pronouns, and the usage of se @xcite . we annotated the 50 spanish-english amr pairs with a divergence classification, being empty if there is no structural divergence, or with at least one type,cause pair. it is possible to have more than one structural divergence so any structural divergence is listed with its cause. figure 5 shows the breakdown of cause of divergence for the 50 pairs in our corpus, as well as the relationship between type of divergence and cause. while different focus and different arg chosen are regularly due to annotation choice, different noncore role chosen or omitted non-core role are much more often due to translation choice. ## related work on cross-lingual meaning representations related work has been done on cross-lingual adaptations of other meaning representations, including the development and analysis of cross-lingual semantic annotation schemes @xcite . the universal dependencies framework has also been useful in the analysis of cross-lingual syntactic divergences @xcite . universal conceptual cognitive annotation (ucca) annotates grammatical meaning while abstracting away from the syntax of the language @xcite . the uniform meaning representation framework extends amr with a focus on quantification and scope, as well as uniformity across languages @xcite . the parallel meaning bank is a corpus of paral-lel texts with corresponding linguistic annotations and discourse representation structure annotations projected from english @xcite . prior work towards the production of parallel meaning banks focused on the alignment of informative translations-translations where more details are included in the target translation than the source text-through an inclusion relation symbol @xcite . work on the parallel meaning bank also includes a comparison of translations as being meaning-preserving or not, and these discrepancies as being largely due to: human annotation error, syntactic differences in definite articles, translation of proper names, or non-literal translations @xcite . alignment for multilingual meaning representations has also been studied in relation to framenet, including recent work looking to unify a multilingual framenet with alignments between all dozen framenet languages @xcite . the prague czech-english dependency treebank (pcedt) similarly considers the adaptation of an english framework to a non-english extension, focusing on dependency annotation for the czech translations of the penn treebank. pcedt highlights some of the issues that arise out of automatically transferring annotation schema to another language. ultimately, the authors find that the annotation schema are not sufficiently fine-grained to provide for a seamless conversion from annotation in one language to annotation in the other, and the difficulty of developing an annotation schema capable of this seamless transformation is unknown @xcite . xl-amr has used transfer learning to automatically produce amr annotations for chinese, german, italian, and french, and provides qualitative analysis suggesting that even with limited training data, the parser is able to manage many structural divergences across languages @xcite . ## conclusion we have presented our annotation schema for classification of structural divergences in cross-lingual meaning representations and released 50 spanish-english annotated examples. we demonstrate with our annotation schema and analysis of the annotated dataset that structural divergence in pairs of cross-lingual meaning representations can serve as a meaningful proxy of divergences between parallel texts. therefore, tools which rely on highly literal translations, such as pre-trained machine translation systems, would benefit from applying this structural divergence annotation schema to crosslingual abstract meaning representations of the data. the scope of our empirical study was limited, however, because there are currently only 50 pairs of spanish-english amr annotations publicly available. studying language pairs with more gold amr data, or adapting the approach to alternate meaning representation formalisms, would further test the utility of our approach.