Linking the Lewis & Short Dictionary to the LiLa Knowledge Base of Interoperable Linguistic Resources for Latin
Authors: Francesco Mambrini, Eleonora Litta, Marco Carlo Passarotti, Paolo Ruffolo (Università Cattolica del Sacro Cuore, 2021)
Topic: Latin Resources

Abstract
English. This paper describes the steps taken to include data from the Lewis & Short bilingual Latin-English dictionary into the Knowledge Base of linguistic resources for Latin LiLa. First, data were extracted from the original XML and matched with entries in LiLa, overcoming ambiguities and structural inconsistencies in the source. Subsequently, senses were modelled using the Ontolex Lemon Lexicographic module (lexicog), so that they could be included in the LiLa Knowledge Base and thus made interoperable with the (meta)data of the linguistic resources for Latin therein interlinked.

Introduction
Since the pioneering times of 1949, when the Jesuit Roberto Busa persuaded Thomas Watson Sr., CEO of IBM, to fund his project aimed at processing the Latin texts of Thomas Aquinas with computers <cit.>, scholars in the areas of Computational Linguistics, Literary Computing and Digital Humanities have built a plethora of linguistic resources for both modern and historical languages.  Particularly over the last two decades, many and diverse linguistic resources have been made available for Latin. These consist in corpora of texts spanning different eras and genres[See, for example, Musisque deoque for Classical Latin poetry <cit.>, CLaSSES, containing epigraphic material <cit.>, the large corpus of Classical Latin prose and poetic texts by LASLA <cit.> and CroALa, which brings together writings by Croatian authors produced between the 10th and 20th centuries <cit.>.], dependency treebanks[Index Thomisticus Treebank <cit.>, Late Latin Charter Treebank <cit.>, UDante <cit.>, PROIEL <cit.> and Latin Dependency Treebank <cit.>.] and lexica[Such as, for instance, valency and subcategorisation lexica <cit.>, the Latin WordNet <cit.> and word lists <cit.>.]. These digital resources join the large set of textual and lexical resources that were created over the centuries for Latin: textual collections, thesauri, lexica, glossaries and mono/bilingual dictionaries. Among the latter, we could mention, for instance, the Oxford Latin Dictionary <cit.>, the Dictionary of medieval Latin from British sources <cit.>, the Forcellini lexicon <cit.> and the still under construction Thesaurus Linguae Latinae <cit.>, many of which are today accessible also in digital format.  However, the impact of these digital resources on the everyday work of classicists is still limited. On the one side, this is due to the still existing divisive dichotomy between “traditional” Humanities and computational approaches. On the other, it is a matter of fact that classicists are not yet put in the best condition to fully exploit all available resources for ancient languages, as these are currently scattered across the web in uncommunicative blocks, using different query languages, data formats, annotation criteria and tagsets.  The last decade has seen a number of exploratory solutions to tackle the sparseness of linguistic resources. Among them, the European infrastructure CLARIN[<https://www.clarin.eu>.] represents a common hub where data and metadata of resources collected in single repositories (at national level) can be searched (through the so-called Virtual Language Observatory) and processed with different tools (through the CLARIN Language Resource Switchboard). As for Classical languages, Logeion[<https://logeion.uchicago.edu/lexidium>.] is a meta-dictionary that allows to query together the lexical entries of several dictionaries for Ancient Greek and Latin, while Corpus Corporum[<http://www.mlat.uzh.ch/MLS/>.] is a meta-collection that allows searches across more than twenty different corpora for Latin. However, what such initiatives still lack is to provide a real interoperability between distributed resources, which would result in interaction at both syntactic (structural) and semantic (conceptual) level.   Syntactic interoperability is defined as `the ability of different systems to process (read) exchanged data either directly or via trivial conversion', using a common data model consisting of shared protocols and data formats. Semantic interoperability, on the other hand, is `the ability to automatically interpret exchanged information meaningfully and accurately in order to produce useful results', by using a set of common linguistic data categories defined in ad-hoc ontologies <cit.>.  Attaining syntactic and semantic interoperability between distributed linguistic resources is the objective of the Linguistic Linked Open Data (LLOD) community, which applies the principles of the Linked Data paradigm <cit.> to the (meta)data contained in linguistic resources. As for Classical languages, the LiLa Knowledge Base (KB)[<https://lila-erc.eu>.] <cit.> makes textual and lexical resources for Latin interact through a commonly used data model, called the Resource Description Framework (RDF) <cit.>, and ontologies developed and shared by the LLOD community. In this way, the linked resources become interoperable with each other as well as with those for other languages described following the same structural and conceptual principles.  Based on a large collection of “canonical forms” (lemmas) - the so-called “Lemma Bank”, LiLa achieves interoperability between resources by linking all those entries in lexical resources and tokens in corpora that point to the same lemma in the LiLa collection.  The lexical resources for Latin linked so far to LiLa include a word formation lexicon <cit.>, a polarity lexicon <cit.>, an etymological dictionary <cit.> and a joint resource providing a manually checked subset of the Latin WordNet and a valency lexicon <cit.>. The most recent among the LiLa connections is the bilingual Latin-English dictionary by Charlton Lewis and Charles Short lewisshort. The inclusion of this type of lexicon in LiLa was much needed, as no resource providing semantic information consisting of translations and definitions was available in the network of connected resources before. Since Lewis & Short is the first lexical resource of its kind included in LiLa, the process of its linking to the KB opened a number of LLOD-related challenges.  This paper describes how such challenges have been tackled and is organised as follows: Section <ref> describes the Lewis & Short dictionary in its main characteristics. Section <ref> discusses the ontologies involved in the modelling phase, the challenges that need to be overcome in the representation of the linguistic data as LLOD (<ref>), and the strategies adopted to represent the dictionary entries using the chosen vocabularies (<ref>). Finally, Section <ref> discusses conclusions and highlights directions for future work.

Conclusion
Perhaps even more than for any other modern language, a great number of lexical resources, either bi- or monolingual, is available for Latin, many of which have already been digitised and disseminated on the web. In this paper, we described a model of how this huge wealth of information can be published using the modern standards of the Semantic Web. The greatest advantage of this approach is that all the lexical resources published according to the same data model can be integrated in a wider network of linguistic information, along with the other digital resources that are connected to it. In the case of the L&S in LiLa, the Latin lexical entries of the bilingual dictionary can be queried together with the information about the same words provided by the other linguistic resources linked to the lemmas in the KB. One example of the fruitful interactions between resources is the possibility to investigate the polysemy of words in relation to their derivation, as recorded in the Word Formation Latin resource, which is also linked to LiLa <cit.>. The adjective hosticus of Figure <ref>, for instance, clearly inherits its two main senses (`hostile' and `foreign') from the same polysemy of the noun hostis 'stranger' or 'enemy', from which it is derived. At the same time, while other resources in LiLa describe the senses of words, such as the Latin WordNet <cit.>, the complex relations between those senses (whether, for instance, one sense is interpreted as a specialised derivation from another) is generally available only in traditional lexical resources like the L&S. The solutions we found to address the challenges raised by the representation of the L&S in LLOD will be reused when we will link further bilingual, as well as monolingual, dictionaries of Latin to the KB. Including such lexical resources in LiLa is an important achievement, as it makes it possible for the KB to interact with linguistic (meta)data for languages other than Latin. Undoubtedly, such an inter-linguistic (re)use of distributed resources is one of the objectives of the LLOD community, to which LiLa contributes by steadily providing it also with new (kinds of) linguistic resources represented in LLOD.