Mapping AMR to UMR : Resources for Adapting Existing Corpora for Cross-Lingual Compatibility (2023)

Abstract: This paper presents detailed mappings between the structures used in Abstract Meaning Representation (AMR) and those used in Uniform Meaning Representation (UMR). These structures include general semantic roles, rolesets, and concepts that are largely shared between AMR and UMR, but with crucial differences. While UMR annotation of new low-resource languages is ongoing, AMR-annotated corpora already exist for many languages, and these AMR corpora are ripe for conversion to UMR format. Rather than focusing on semantic coverage that is new to UMR (which will likely need to be dealt with manually), this paper serves as a resource (with illustrated mappings) for users looking to understand the fine-grained adjustments that have been made to the representation techniques for semantic categoriespresent in both AMR and UMR.

## introduction even with the overwhelming improvement in performance in natural language processing (nlp) brought about by recent transformer architectures @xcite @xcite , there is an enduring interest in symbolic meaning representations in the community. in the decade since english abstract meaning representations (amrs) were launched, they have become increasingly popular and feature in several successful nlp applications @xcite @xcite . the 60k sentence dataset of english annotations available via ldc 1 has contributed significantly to this popularity. there is also growing interest in projecting english amrs onto other languages to explore their suitability as a cross-lingual representation @xcite @xcite @xcite , with mixed 1 amr 3.0: https://doi.org/10.35111/44cy-bp51 success @xcite . in parallel with this exploration, a serious study has been made of the more english-centric aspects of amrs, with the goal of moving amrs in the direction of uniform meaning representations (umrs) as an annotation framework that can more readily be applied to all languages. as discussed in @xcite , umr was developed with cross-linguistic scope in mind, paying careful attention to linguistic typology and typologically diverse languages. for researchers familiar with amr, and especially for those who have already been annotating datasets in other languages with amr-like annotations, it is important to understand exactly the ways in which amr and umr are similar and the crucial ways in which they differ, as discussed here. this should be of interest to anyone familiar with amr who wants to adapt it to another language, or who already has an amr dataset that can be retrofit to be more compatible with umr. in our previous umr publications, we introduced the schema by explaining how it carves up conceptual space into categories that are applicable to typologically diverse languages @xcite @xcite . special consideration has been given to the needs of field linguists who may be approaching semantic annotation for the first time as well as to the semantic coverage that is new for umr, such as modal @xcite , aspectual @xcite and scopal relations @xcite . in this paper we turn to more direct mappings from amr-elements to umr-elements. we start by reviewing how amr carves up conceptual space into graph elements (section 2), and then show how these elements overlay those of the umr schema, focusing on retention, alteration and removal. section 3 focuses on role-role mappings, section 4 on abstract roleset mappings, and section 5 on abstract concept mappings. we limit our discussion to sentence-level graphs. in the appendix, we illustrate these mappings with easilydigestible graphics. as the developers of umr, nothing would delight us more than a rush to convert existing amr datasets to umr. indeed, amr corpora already exist in a variety of languages: english 2 , chinese 3 , czech @xcite , spanish @xcite , turkish @xcite , vietnamese @xcite , portuguese @xcite , korean @xcite , persian @xcite , and more. some parallel corpora also exist @xcite , which will be especially useful if converted to umr. much conversion of amr corpora to umr corpora should be able to be accomplished deterministically, with unique issues arising for each language. the body of this paper pertains most directly to ldc's 3.0 english amr release, which consists of 60,000 sentences, 7800 of which are annotated with multisentence amr @xcite . english amr has also been extended to special domain projects outside of the ldc release. 4 sections 6.1 and 6.2 focus on existing czech and chinese data sets, considering issues that are expected to arise when converting existing amr corpora to umr format. umr improves on amr in two major ways: first by adjusting the amr schema to make it more cross-linguistically applicable, and second, by adding new semantic coverage to the schema in the form of sentence-level graph elements for tense, aspect, modality, and scope, as well as documentlevel dependency structures for temporal relations, 2 isi's amr main page: https://amr.isi.edu/ 3 chinese amr main page with release: https://www.cs.brandeis.edu/ clp/camr/camr.html 4 these range in size from just over 1000 with dialamr @xcite to 8000 with nih thyme @xcite to over 10,000 for minecraft spatialamr @xcite , to mention only those we know well. modality, and coreference. see vigus et al. (2019), vigus et al. (2020), and pustejovsky et al. (2019) for in depth instruction on these additions. the umr-writer @xcite also creates alignments between tokens in a surface level representation and elements in its graph. amr fails many non-english languages in two basic ways. first, the categories amr uses to divide semantic space sometimes fail to cover necessary distinctions in a given language or fail to align with the language's category boundaries. second, the style of morphosyntactic expression used by a language may be incompatible with conversion from surface forms to graph structures. amr is based on predicate argument structures and assumes that a predicate and its arguments are distinct tokens that can each be plugged into its own node in the graph. this creates problems for polysynthetic and agglutinating languages in which an event, its modifiers, and its participants may all be morphologically bound together. applying english-based amr practices either disrupts surface lexical units or produces single node graphs so semantically specific that they are unlikely to come up twice in a corpus. figure 3 (appendix a .2) demonstrates the second point with a side-by-side comparison of amr and umr graphs for an arapaho sentence and its english translation. language-specific rolesets: amr represents the semantics of a given sentence as a rooted, directed, acyclic graph consisting of nested predicate argument structures @xcite . most of the predicate argument structures come in the form of lexical rolesets, taken from a valency lexicon associated with the language to be annotated. amr was originally created with english in mind, and english amr uses the english prop-bank roleset lexicon @xcite @xcite . chinese amr relies on the chinese prop-bank, and czech amr uses the czech pdt-vallex valency lexicon @xcite . in general, lexical rolesets are created for eventualities (events and states) and are ambiguous for the parts of speech used to express them. rolesets consist of a predicate id, for sense disambiguation, and a set of numbered roles with lexicalized descriptions that are considered semantically primary to the sense. ## mapping roles in order to better serve a typologically diverse range of languages, umr uses an updated set of general semantic roles. many are taken directly from amr, although some have been renamed, semantically expanded or contracted, or split. others have been replaced with non-role strategies in umr, and a small handful have been discontinued and not replaced. changes are motivated by the cross-linguistic argument realization patterns in the valpal database @xcite . each role in umr still has an inverse and a roleset that reifies it. this section presents the ways in which roles have been adjusted to be more semantically comprehensive for umr, as illustrated in figure 1 . a major feature of umr is the ability to use only general semantic roles for languages without roleset lexicons (see stage 0 annotation in @xcite ). due to this change, rather than having a single list of roles as in amr, umr groups its roles into participant roles (primary arguments of eventualities), nonparticipant roles (other modifiers), and attributes (roles that take only a fixed set of values). most adjustments from amr to umr target participant roles. new roles: the concepts/roles in the top (pink) boxes in figure 1 occur in amr, but not as general roles. of these, new participant roles (left) appear exclusively as numbered arguments (typically arg0 or arg1) of language-specific lexical rolesets, and new nonparticipant roles (right) as abstract concepts or abstract rolesets. the new non-participant roles are all discourse relation roles (see section 4) with the exception of :vocative, which amr deals with by inferring an english-specific say-01 roleset. a general role for vocatives is preferable for non-english corpora. renamed roles: the roles in the next boxes down in figure 1 (purple) have been renamed so as to better describe the semantic categories they cover. :companion and :affectee both have shifted semantic boundaries compared to their amr counterparts. :companion now applies to animate participants only ('i traveled with mary') and is no longer to be used with entity modification (as in 'a pizza with pineapple'). instances of the latter sort should be handled now with the appropriate topological (:part) or discourse relations (and) depending on the situation. :affectee now includes maleficiaries as well as beneficiaries, filling a sometimes uncomfortable gap in amr. the other roles (:place, :temporal, and :list-item) are more cross-linguistically descriptive than their previous forms. :place and :temporal are better labels for participants that are abstract or metaphorically extended. note that :time is still used for clock times under date-entity. :list-item replaces :li, which was considered too opaque a label. split roles: roles that are split into finer-grained categories to better support cross-linguistic seman-tic role diversity are next in figure 1 (green). in most cases, the original role name has been retained but applied to a narrower category. the exceptions are amr's :consist-of and :destination. :consist-of is dispreferred as a label because of its '-of' ending, which is ambiguous with inverse roles. :destination has been split across :goal and :recipient because of how :destination's split contrasts with :source's split. :source was split into three roles: :source (the start-point in motion events that involves separation of a part from a whole), :start (the start-point for other motion events), and :material (the material in a creation event). :destination on the other hand was split along animacy lines, with :recipient being used for animate end-points of sent-motion events, and :goal being used, in effect, for participants that contrast with any of the three :sourcebased roles. in other words, :goal captures endpoints in motion events regardless of whether the entity in motion becomes part of the end-point, and also products in creation events. :goal is considered to be more appropriately general than :destination across these types. :consist-of is also split across three narrower roles-:part, :group, and :material. these are largely topological distinctions. in amr, :mod is used as a catch-all role for modifiers with no clear home in one of the other roles. in umr, we split this duty between :mod and :other-role. :other-role should be used as a catch-all participant role, whereas :mod should be used as a catch-all nonparticipant role. in other words, :mod should still be used for demonstratives and the like. we note too that umr is much more flexible about leaving surface concepts unannotated if they do not fit clearly into the schema, somewhat reducing the need for a catch-all role. (exactly which concepts should be left unannotated for this reason is a question that needs to be resolved on a language-by-language basis, depending on how conceptual space is morphosyntactically distributed. consider the option to omit 'just' and 'back-and-forth' as their own :mod nodes in the english umr in appendix a.2.) :other-role is more likely to be used by low-resource languages undergoing stage 0 annotation. removed roles: umr discontinues use of a number of roles (appendix a.1). some of these were simply shortcuts, while others do not fit into the current schema as roles. the most important re-moved role is :domain, which amr used for identity relations in place of a copular roleset. :domain was used in places where property, object, or identity relations were expressed clausally. it was considered an inverse of :mod, so :mod has been given a new inverse, :mod-of. in umr, these clausal expressions are now handled using the rolesets of nonprototypical predication (formerly 'nonverbal clauses'), discussed in section 4. inverse roles appear in the form :<@xmath0:<@xmath1:mod/:mod-of above), with the inverse capitalized. as noted with :consist-of, umr does not use base roles ending in -of, thus eliminating ambiguity. amr provides reified rolesets for most of its general roles, although there are a few holes, as with :direction and :path. most of amr's reifications are constructed fairly consistently. those that were created for amr had -91 suffixes, but sometimes, english-specific rolesets were used. this turns out to be an uncomfortable set-up for annotation of non-english languages, since englishsourced roleset names may not be obviously identi-8 umr website: https://umr4nlp.github.io/web/ fiable as reifications (e.g., last-01 for :duration, concern-02 for :topic). also problematically, the english-sourced rolesets don't always have exactly the same semantic coverage as the roles they reify. for example, age-01 is aspectuallyincompatible with :age, as it pertains to an aging event rather than a property. age-01 also includes an :arg0 for the causer/agent of the aging event, which is not applicable to the :age role. because of these issues, the entire set of reified rolesets has been overhauled to bring them into alignment and make them more cross-linguistically appropriate. this involves new conventions for naming the rolesets and new conventions for naming and structuring their arguments. we believe these changes are a great improvement that will benefit all annotators moving forward. naming conventions: reification rolesets are now named consistently, as follows: 1) each has a -91 suffix. if multiple rolesets exist for the same concept, numbering continues with -92 and so on; 2) each starts with a have-prefix, with the exception of be-polite-91, which we keep as a stylistic choice; 3) the content between 'have-' and '-91' is the name of the role being reified. appendix a.3 shows reification rolesets for all umr roles. argument structuring conventions: reification rolesets are also structured and numbered consistently now, as follows: 1) each roleset starts with :arg1, as :arg0 is reserved for agentive/causal arguments; 2) :arg1 is used for the event or entity that would serve as the head of the unreified role in a graph, and :arg2 is for the value that would be annotated under the unreified role. other arguments may be possible but are less conventionalized. see how the old reification for :accompanier was reconfigured as have-companion-91 below: ## mapping abstract concepts as mentioned in section 2, amr includes a number of abstract concepts such as x-entity and x-quantity types, named entity types, mathematical concepts, and other annotation-support concepts like amr-unintelligible. by-and-large, these are unchanged in umr. of course those referencing 'amr-' have been updated to reference 'umr-' (e.g. umr-unknown, etc.). all x-entities and x-quantities are still in use. see appendices a.7 and a.8. when a named entity is identified, umr assigns a semantic type to it, following the practice of amr. these types are organized hierarchically, and annotators aim to use the most specific type possible. umr makes a number of adaptations to the amr hierarchy in order to make the named entity types more cross-linguistically applicable and practical. following the general spirit of making umr ontologies hierarchical so that annotators of each language can select the level of granularity they are comfortable with, umr arranges the named entity types hierarchically in a lattice. umr also adds categories that are needed when annotating indigenous languages, as their societies are often organized in such a way that the amr types did not fit well. for instance, entity types like "clan" are not available in amr but are added in umr. the umr named entity type heierarchy is "backward compatible" in that it is a superset of the amr entity types, and existing amr named entity types can be automatically mapped to umr. see appendix a.9. ## czech and chinese corpora adapting umr annotation to other languages need not necessarily mean starting from scratch. in this section, we describe preliminary work planning the use of existing resources for czech and chinese to build umr-annotated corpora. for both languages, there are existing amr corpora (of varying size), as well as semantically-annotated corpora, for example in the styles used for the shared tasks on meaning representation parsing @xcite . either type of resource can provide a starting point for developing a umr corpus with less effort. ## conclusion as more languages are annotated with umr, we continue to identify ways the schema can be further refined to support cross-lingual expressivity. however, the process with new languages can be slow. converting existing amr corpora to umr is an efficient way to grow the overall umr corpus. also, users with expertise in how amr categories map to real language conceptual space can help identify the more nuanced areas in which umr can improve on amr. we expect the mappings outlined in this paper to be important support for users who wish to be a part of this process.