S panish Verbal Synonyms in the S yn S em C lass Ontology (2023)

Abstract: This paper presents ongoing work in the expansion of the multilingual semantic event-type ontology SynSemClass (Czech-English-German) to include Spanish. As in previous versions of the lexicon, Spanish verbal synonyms have been collected from a sentence-aligned parallel corpus and classified into classes based on their syntactic-semantic properties. Each class member is linked to a number of syntactic and/or semantic resources specific to each language, thus enriching the annotation and enabling interoperability. This paper describes the procedure for the data extraction and annotation of Spanish verbal synonyms in the lexicon.

## introduction the work presented in this paper is part of a larger project aiming at building an event-type multilingual ontology. synsemclass (ssc) @xcite is a multilingual verbal lexicon where contextually-based synonymous verbs are classified into classes based on the semantic and syntactic properties they display. synonymy here is understood in terms of contextually-based synonymy: a verb considered a member of a class must reflect the same (or similar) meaning expressed by the class in the same context (i.e., it has a similar "semantic behavior" as the other verbs) both monolingually and cross-lingually. apart from providing fine-grained syntactic-semantic multilingual annotation, synsemclass also contributes to research by building a database that links several resources in different languages @xcite . the information gathered in the lexicon allows for a comparison across languages relevant for linguistic research at the same it provides curated data for natural language processing tasks, such crosslingual synonyms or synonymy discovery. this paper presents ongoing work on the extension of synsemclass to include a fourth language, spanish. specifically, section 2 introduces the synsemclass lexicon and section 3 describes the set of spanish resources linked to synsemclass. the method for data extraction and annotation of spanish verbal synonyms is presented in section 4. the results obtained and the limitations encountered during the process are summarized in section 5. the paper closes (section 6) with a summary of the main findings and with some hints for future work. entries in the lexicon are grouped into individual multilingual (for now, english, czech, and german) verbal synonym classes. each class is considered similar to an ontological unit and it is assigned a specific set of roles (i.e. roleset), which expresses the prototypical meaning of the class @xcite . the most important criterion for inclusion of a particular verb (sense) into a given class is the mapping of each of the semantic roles specified in the class roleset to the verb valency slots (represented by a syntactic-semantic functor 1 ) captured in the valency frame (role ↔ argument mapping). while sharing the same set of roles is a requirement for a verb to be included in a class, roles can be expressed by different morphosyntactic realizations and be subject to additional restrictions @xcite . another criterion for verb sense inclusion is a functionally adequate relationship (i.e., in terms of translation, the verb senses are considered synonymous in the given context(s) if the translated verb in the target language adequately expresses the functional intent of the original language) between the meanings of all class members in one synonym class. the synsemclass class members (individual multilingual synonym verb senses, cms) are linked to entries in similar language-specific syntactic and/or semantic databases @xcite . the english entries are linked to framenet @xcite , verbnet @xcite and prop-bank @xcite , the german entries to framenet des deutschen (fdd) foot_1 , the universal proposition bank (upb) @xcite foot_2 , the elektronisches valenzlexikon des deutschen foot_3 (electronic german valency lexicon, in short e-valbu) @xcite , and woxikon foot_4 , and the czech entries to pdt-vallex @xcite , which was used for building the czech part of the pcedt, to the lexicon of czech and english translation equivalents called czengvallex @xcite and to vallex @xcite . the latest release, synsemclass4.0 (figure 1 ), is dated june 2022 and contains 883 classes with approx. 6,000 cms. 6 as shown in figure 1 , each class in the lexicon is named using the most prototypical verb in each language (allow, dovolit, erlauben). for each class, the online version of the lexicon displays the information related to the roleset assigned to the class (authority, permitted, affected), the list of class members in each language, their valency frame (e.g., for english allow, the valency frame is act, eff, pat) and the related senses in the external resources used for each language (e.g., for english, english verbnet (ev), framenet (fn) or ontonotes (on), among others). it is also possible to display the corpus examples selected to illustrate the class members. the work on german has thus been moved to this version (from the previous version 3.5); the fourth version of the lexicon is more complete and it has additional corrections (such as some classes having been merged, etc.) also, it adds the integration of class and roles definitions. the next release of synsemclass (presumably version 5, planned for early spring 2023) will be enriched by spanish synonymous verbs as described here. ## resources following @xcite , the minimal set of resources required to add a language to synsem-class is: (i) a parallel corpus and (ii) (at least) one lexical resource containing syntactic and semantic information. this section describes the corpus and the lexical resources used for spanish. ## extending synsemclass by spanish this section describes two phases of the annotation of spanish verbal synonyms: (i) automatic data extraction (section 4.1) and (ii) manual data annotation (section 4.2). ## results and limitations the spanish part of the synsemclass lexicon is still in its early stages, but results have been encouraging so far even if the number of classes annotated represents a small part of the lexicon (72 classes, 5,200 verbs). 18 the results obtained are especially relevant from a methodological perspective. while some changes in the tools used and/or in the annotation process can be expected as more data is processed, the results obtained so far set the basis for future work on spanish. since the addition of spanish to synsem-class was devised as an opportunity to "simulate" a scenario where a team works almost independently (that is, only with central support), the results obtained are also relevant for the future extension of the lexicon. apart from the methodological aspects mentioned, adding a new language from a different linguistic subfamily enriches the existing lexicon by providing more linguistic evidence (including special cases, such as lvcs or prepositional complements) that led to a refinement of synonym classes. in order to accommodate new data, new classes will be added to the lexicon and it will be necessary to split or merged existing classes as more verbs are added to the lexicon. regarding spanish and to the best of our knowledge, synsemclass has become the first multilingual richly annotated resource of a general ontology type that includes spanish. it is also the first one in linking various existing spanish lexical resources, in line with other initiatives such as the uvi for english. even if theoretically feasible, including a new language in synsemclass inevitably leads to certain issues that need to be addressed regarding technical, organizational and resource-related aspects, some of them being already tackled in @xcite . in particular for spanish, the main issues arising concern the limitations related to the resources available. while the czech-english part of the lexicon relies on an annotated humantranslated parallel dependency corpus with semantic information and on rich lexical resources, the comprehensiveness of the resources for spanish is more limited as, to the best of our knowledge, no deeply syntactically annotated parallel corpus (similar to the pcedt corpus) or bilingual verbal valency lexicon are available. another limitation is the scarce representation of dialectal varieties other than european spanish. although some of the resources (e.g., adesse or spanish framenet) are not restricted to european spanish, its coverage is uneven and entries do not contain specific information in this respect. to avoid this limitation where possible, verb senses from varieties other than european spanish are included in ssc and specified in the lexicon based on the information provided by two dictionaries (with the limitations lexicographic resources entail). ## conclusions and future work this paper has described the process of data processing and annotation and the initial results of adding spanish to synsemclass. based on the method used for adding german class members to the resource, spanish synonymous verbs have been extracted from a parallel corpus and linked to a set of lexical resources available. while part of the methodology for adding spanish to the lexicon built on previous work on german, the specific features of the resources used for spanish have required to make changes (some quite substantial, at least from the technological point of view) in the process of data extraction and adapt the tool used for annotation. spanish is one step more towards the creation of a collaborative multilingual event-type ontology. for the time being, plans in the near future include extending the lexicon to cover korean. while the addition of german and spanish in the lexicon will certainly provide the basis for the addition of more languages, it is assumed that both the lexicon and the tools will continually evolve to adapt to the intricacies of new languages. from a more global perspective, this project is part of a larger early-stage project aimed at multilingual knowledge representation. synsemclass classes will serve as the grounding for the events and states included in such representation, connecting (relating) all other entities in the resulting representation which will also be grounded (by other means). while some verb annotation experiments have been done so far, a detailed specification of the process is still to be developed.