The R omanian W ordnet in Linked Open Data Format (2023)

Abstract: In this paper we present the standardization of the Romanian Wordnet by means of conversion to the Linked Open Data format. We describe the vocabularies used to encode data and metadata of this resource. The decisions made are in accordance with the characteristics of the Romanian Wordnet, which are the outcome of the development method, enrichment strategies and resources used for its creations. By interlinking with other resources, words in the Romanian Wordnet have now the pronunciation associated, as well as syntagmatic information, in the form of contexts of occurrences.

## introduction the romanian wordnet (rown) as available today has been created starting with the balkanet project @xcite . the working methodology @xcite followed mainly (see below) the expand approach @xcite : synsets from the princeton wordnet @xcite (pwn) were translated into romanian and the relations between implemented synsets were transferred from corresponding pwn synsets. using a bilingual electronic dictionary, the literals in the selected pwn synsets were first automatically translated and the romanian equivalents were suggested to lexicographers as literals to be included in the romanian synsets. for each selected word, its sense was chosen from the parsed electronic version of the explanatory dictionary of romanian (dex) @xcite . the selection foot_0 of the synsets to be implemented during balkanet was done so as to cover words with high frequency (according to corpora available at that moment), polysemy (according to the number of senses in dex), as well as avoidance of dangling nodes in the rown structure (which meant that choosing a synset to implement in romanian implied choosing all its unimplemented synsets in pwn up to the unique beginners of the hierarchies, in the case of nouns and verbs, which have a hierarchical structure). the synsets ids were also transferred from pwn. the balkanet team also aimed at reflecting some of the specificities of this geographic and cultural region in the wordnets under development. consequently, a various number of such synsets were included in the wordnets: for romanian, there were 541 synsets. they were included in the hierarchies mostly as hyponyms of existing synsets. their ids were generated so as to keep them distinct from those of the translated synsets. one such synset contains the literal tobȃ with the gloss "a type of cold cooked meat, containing pieces of chopped meat, fat, offal, all stuffed in a pig's stomach and suspended din aspic". it is a romanian traditional cold dish, specific to christmas season and looking like a wide sausage. for this reason it is a hyponym of the noun cârnat, which translates the english sausage. besides the automatic transfer of the semantic relations holding between equivalent english synsets, the romanian team also transferred the lexical relations from pwn: these are relations marked at the literal (not synset) level in pwn. examples include antonymy and derivation relations. in the case of the former, it was considered that this lexical relation has a conceptual counterpart: the semantic opposition between the concepts lexicalized by the words in antonymy relations @xcite . consider the synsets {sterile, unfertile, infertile} (gloss: "incapable of reproducing") and the synset {fertile} (gloss: "capable of reproducing"). antonymy is marked between sterile and fertile in pwn. however, speakers understand a semantic opposition between fertile and infertile, as well as between fertile and unfertile foot_1 . given that there is no literal correspondence between pwn and rown, which could have allowed for the transfer of antonymy at literal level, this assumption allowed for its transfer at the synset level. thus, the rown equivalents of such synsets establish between them an antonymy relation. ## conversion of rown to lod format linked data (ld) refers to a set of best practices in publishing structured data on the web @xcite . when an open type of license, namely creative commons (cc), is associated with a resource, then we talk about linked open data (lod). the conversion of romanian language resources to the lod format is an internal project 3 of the romanian academy research institute for artificial intelligence, running in parallel with the nexuslinguarum cost action 4 . we have already made several resources available in this format and, more important, this way some of them are made open to the community for the first time: this is also the tual production of live offspring and is the antonym of infertility", https://academic.oup . the lod format for rown was automatically generated using a conversion tool developed in c#. preliminary actions that had to be taken were: in accordance with the recommended standard for representing wordnets, our turtle rdf lod representation model is mainly based on the ontolex-lemon vocabulary @xcite developed by the ontology-lexica community group (ontolex), but is also supported by other useful vocabularies like the owl web ontology language foot_4 , the wordnet specific ontology wn foot_5 and the variation and translation lemon module vartrans 9 to represent the various encoded properties. the serialisations in lmf-xml and json format are also available, but the linking with external resources was implemented only in the turtle rdf format, which will, therefore, be the focus of this section. as can be seen in figure 1 , the main level entry in the original xml format of rown was the synset, comprising an id, the part-of-speech label (pos), a definition, the synonym set and a list of relations specified by their target synset (ilr1 and ilr2 objects) and their relation type (type1, type2). the synonym set was a list of different literals together with their associated senses, unique to the synset they belong to. to comply with the ontolex-lemon model 10 , the information in rown had to be restructured as shown in figure 2 . the color code for the nodes in the diagram is the following: blue stands for objects, yellow for properties and the correspondence between the new classes and properties and the ones in the original format (see figure 1 ) are marked in red: e.g., each lexicalentry in rown has an associated canonicalform object and the ontolex:writtenrep property of this object has as value one of the literals in the synonym set of one of the original format synsets. basically, the information in the original file was organised around synonym sets (with specific meaning), accompanied by their associated lexical representations (literal1, literal2, etc.), while in the lod format the data is organised around literals, accompanied by their possible meanings (represented as a list of senses: sense1, sense2, etc.). the new format has four types of main entries: ## interlinking one of the important advantages lod comes with is the possibility of putting language resources in a broader context, by means of interlinking them, which further ensures their fair characteristics @xcite . ## use case scenarios ld provides mechanisms for exploiting the resources' content, by means of their common elements; these are either identifiers (see ili) or words co-occurring in several resources. the resources we have converted to lod format are made available for querying as sparql endpoints 16 . this allows for federated queries 17 to be created and, thus, exploit the content of all these resources or only some of them. such an example would be a conceptual search in a speech corpus, as described by @xcite . the following steps are taken: (i) the input word (i.e., a possible lexicalization of a concept of interest) is looked up in rown and conceptually identical words (i.e., literals in the same synset, or synonyms) are re-16 https://relate.racai.ro/datasets/ 17 https://www.w3.org/tr/ sparql11-federated-query/ trieved; (ii) for each literal, its rolex entries are found by means of the ili identifiers, and thus its inflectional paradigm is retrieved; (iii) these forms are then located in the files of a speech corpus. the interlinked rown and rolex prove their usefulness in a question answering scenario related to covid-19 @xcite . an important element for the system being able to find an answer in a set of documents was for it to be able to recognize all the various ways in which a question can be formulated. after the manual creation of several such possible formulations, two steps were taken for expanding them: (i) content words were associated to other semantically related words (synonyms, hypernyms) in rown by exploiting the semantic relations therein, and (ii) these newly found words were associated with their inflected forms from rolex, also taking advantage of the fact that the interlinking between these two resources was made with manual assignment in the case of homographs. the pos-tagging of the question and the morphosyntactic descriptions in rolex helped to find the inflected form necessary in each context. ## access to lod rown the lod format of rown is available for download on the website of the internal lod project (see section 4). this is the first time the whole romanian wordnet is made freely available for download. previously @xcite , only a core of it was accessible. only by means of the dedicated api @xcite could any kind of information therein be exploited. a sparql endpoint is also made available for it on the sparql apache jena fuseki server installed on one of our servers. the resource's metadata has already been registered in the lod cloud foot_7 , as well as in the european language grid catalogue foot_8 . ## conclusions and future work although not currently under development, rown is still considered a valuable resource for the romanian language, as shown by its recent use in a query expansion task @xcite and its evaluation in a word similarity task @xcite . we have presented here its conversion to lod specifications, a new format that can help rown become a more fair resource. in the future, we are going to add the balkan-specific concepts and derivational relations to the lod rown and then reuse the resource in its interlinked format in various scenarios.