Approches Neuronales pour la Reconstruction de Mots Historiques

In historical linguistics, cognates are words that descend in direct line from a common ancestor, called their proto-form, andtherefore are representative of their respective languages evolutions through time, as well as of the relations between theselanguages synchronically. As they reflect the phonetic history of the languages they belong to, they allow linguists to betterdetermine all manners of synchronic and diachronic linguistic relations (etymology, phylogeny, sound correspondences).Cognates of related languages tend to be linked through systematic phonetic correspondence patterns, which neuralnetworks could well learn to model, being especially good at learning latent patterns. In this dissertation, we seek tomethodically study the applicability of machine translation inspired neural networks to historical word prediction, relyingon the surface similarity of both tasks. We first create an artificial dataset inspired by the phonetic and phonotactic rules ofRomance languages, which allow us to vary task complexity and data size in a controlled environment, therefore identifyingif and under which conditions neural networks were applicable. We then extend our work to real datasets (after havingupdated an etymological database to gather a correct amount of data), study the transferability of our conclusions toreal data, then the applicability of a number of data augmentation techniques to the task, to try to mitigate low-resourcesituations. We finally investigat in more detail our best models, multilingual neural networks. We first confirm that, onthe surface, they seem to capture language relatedness information and phonetic similarity, confirming prior work. Wethen discover, by probing them, that the information they store is actually more complex: our multilingual models actuallyencode a phonetic language model, and learn enough latent historical information to allow decoders to reconstruct the(unseen) proto-form of the studied languages as well or better than bilingual models trained specifically on the task. Thislatent information is likely the explanation for the success of multilingual methods in the previous worksEn linguistique historique, les cognats sont des mots qui descendent en ligne directe d'un ancêtre commun, leur proto-forme, et qui sont ainsi représentatifs de l'évolution de leurs langues respectives à travers le temps. Comme ils portent eneux l'histoire phonétique des langues auxquelles ils appartiennent, ils permettent aux linguistes de mieux déterminer toutessortes de relations linguistiques synchroniques et diachroniques (étymologie, phylogénie, correspondances phonétiques).Les cognats de langues apparentées sont liés par des correspondances phonétiques systématiques. Les réseaux deneurones, particulièrement adaptés à l'apprentissage de motifs latents, semblent donc bien un bon outil pour modéliserces correspondances. Dans cette thèse, nous cherchons donc à étudier méthodiquement l'applicabilité de réseaux deneurones spécifiques (inspirés de la traduction automatique) à la `prédiction de mots historiques', en nous appuyantsur les similitudes entre ces deux tâches. Nous créons tout d'abord un jeu de données artificiel à partir des règlesphonétiques et phonotactiques des langues romanes, que nous utilisons pour étudier l'utilisation de nos réseaux ensituation controlée, et identifions ainsi sous quelles conditions les réseaux de neurones sont applicables à notre tâched'intérêt. Nous étendons ensuite notre travail à des données réelles (après avoir mis à jour une base étymologiquespour obtenir d'avantage de données), étudions si nos conclusions précédentes leur sont applicables, puis s'il est possibled'utiliser des techniques d'augmentation des données pour pallier aux manque de ressources de certaines situations.Enfin, nous analysons plus en détail nos meilleurs modèles, les réseaux neuronaux multilingues. Nous confirmons àpartir de leurs résultats bruts qu'ils semblent capturer des informations de parenté linguistique et de similarité phonétique,ce qui confirme des travaux antérieurs. Nous découvrons ensuite en les sondant (probing) que les informations qu'ilsstockent sont en fait plus complexes : nos modèles multilingues encodent en fait un modèle phonétique de la langue, etapprennent suffisamment d'informations diachroniques latentes pour permettre à des décodeurs de reconstruire la proto-forme (non vue) des langues étudiées aussi bien, voire mieux, que des modèles bilingues entraînés spécifiquement surcette tâche. Ces informations latentes expliquent probablement le succès des méthodes multilingues dans les travauxprécédents

Évolution phonétique des langues et réseaux de neurones : travaux préliminaires

National audienceCognate prediction is a key task in historical linguistics that presents a number of similarities withmachine translation. However, although neural methods are now widespread in machine translation,they are still largely unused in historical linguistics. In this paper, we study the performance ofneural methods (more specifically encoder-decoder networks) for the task of cognate prediction. Wefocus in particular on the types of data that can be used for this task, and compare the performanceof statistical and neural methods. We show that sound correspondances can only be learned usingcognate datasets, and that statistical and neural methods seem to have complementary strengths andweaknesses regarding what they learn about the data.La prédiction de cognats est une tâche clef de la linguistique historique et présente de nombreuses similitudes avec les tâches de traduction automatique. Cependant, alors que cette seconde discipline a vu fleurir l’utilisation de méthodes neuronales, celles-ci restent largement absentes des outils utilisés en linguistique historique. Dans ce papier, nous étudions donc la performance des méthodes neuronales utilisées en traduction (les réseaux encodeur-décodeur) pour la tâche de prédiction de cognats. Nous nous intéressons notamment aux types de données utilisables pour cet apprentissage et comparons les résultats obtenus, sur différents types de données, entre des méthodes statistiques et des méthodes neuronales. Nous montrons que l’apprentissage de correspondances phonétiques n’est possible que sur des paires de cognats, et que les méthodes statistiques et neuronales semblent avoir des forces et faiblesses complémentaires quant à ce qu’elles apprennent des données

Probing Multilingual Cognate Prediction Models

International audienceCharacter-based neural machine translation models have become the reference models for cognate prediction, a historical linguistics task. So far, all linguistic interpretations about latent information captured by such models have been based on external analysis (accuracy, raw results, errors). In this paper, we investigate what probing can tell us about both models and previous interpretations, and learn that though our models store linguistic and diachronic information, they do not achieve it in previously assumed ways

Comparing Statistical and Neural Models for Learning Sound Correspondences

Due to the COVID-19 pandemic, the workshop will not take place. However, the proceedings are published online.International audienceCognate prediction and proto-form reconstruction are key tasks in computational historical linguistics that rely on the study of sound change regularity. Solving these tasks appears to be very similar to machine translation, though methods from that field have barely been applied to historical linguistics. Therefore, in this paper, we investigate the learnability of sound correspondences between a proto-language and daughter languages for two machine-translation-inspired models, one statistical, the other neural. We first carry out our experiments on plausible artificial languages, without noise, in order to study the role of each parameter on the algorithms respective performance under almost perfect conditions. We then study real languages, namely Latin, Italian and Spanish, to see if those performances generalise well. We show that both model types manage to learn sound changes despite data scarcity, although the best performing model type depends on several parameters such as the size of the training data, the ambiguity, and the prediction direction

Caveats of Measuring Semantic Change of Cognates and Borrowings using Multilingual Word Embeddings

International audienceCognates and borrowings carry different aspects of etymological evolution. In this work, we study semantic change of such items using multilingual word embeddings, both static and contextualised. We underline caveats identified while building and evaluating these embeddings. We release both said embeddings and a newly-built historical words lexicon, containing typed relations between words of varied Romance languages

Methodological Aspects of Developing and Managing an Etymological Lexical Resource: Introducing EtymDB 2.0

Due to COVID19 pandemic, the 12th edition is cancelled. The LREC 2020 Proceedings are available at http://www.lrec-conf.org/proceedings/lrec2020/index.htmlInternational audienceDiachronic lexical information was mostly used in its natural field, historical linguistics, until recently, when promising but not yet conclusive applications to low resource languages machine translation started extending its usage to NLP. There is therefore a new need for fine-grained, large-coverage and accurate etymological lexical resources. In this paper, we propose a set of guidelines to generate such resources, for each step of the life-cycle of an etymological lexicon: creation, update, evaluation, dissemination, and exploitation. To illustrate the guidelines, we introduce EtymDB 2.0, an etymological database automatically generated from the Wiktionary, which contains 1.8 million lexemes, linked by more than 700,000 fine-grained etymological relations, across 2,536 living and dead languages. We also introduce use cases for which EtymDB 2.0 could represent a key resource, such as phylogenetic tree generation, low resource machine translation and medieval languages study

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Can Cognate Prediction Be Modelled as a Low-Resource Machine Translation Task?

International audienceCognate prediction is the task of generating, in a given language, the likely cognates of words in a related language, where cognates are words in related languages that have evolved from a common ancestor word. It is a task for which little data exists and which can aid linguists in the discovery of previously undiscovered relations. Previous work has applied machine translation (MT) techniques to this task, based on the tasks' similarities, without, however, studying their numerous differences or optimising architectural choices and hyper-parameters. In this paper, we investigate whether cognate prediction can benefit from insights from low-resource MT. We first compare statistical MT (SMT) and neural MT (NMT) architectures in a bilingual setup. We then study the impact of employing data augmentation techniques commonly seen to give gains in low-resource MT: monolingual pretraining, backtranslation and multilinguality. Our experiments on several Romance languages show that cognate prediction behaves only to a certain extent like a standard lowresource MT task. In particular, MT architectures, both statistical and neural, can be successfully used for the task, but using supplementary monolingual data is not always as beneficial as using additional language data, contrarily to what is observed for MT

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Zephyr: Direct Distillation of LM Alignment

We aim to produce a smaller language model that is aligned to user intent. Previous research has shown that applying distilled supervised fine-tuning (dSFT) on larger models significantly improves task accuracy; however, these models are unaligned, i.e. they do not respond well to natural prompts. To distill this property, we experiment with the use of preference data from AI Feedback (AIF). Starting from a dataset of outputs ranked by a teacher model, we apply distilled direct preference optimization (dDPO) to learn a chat model with significantly improved intent alignment. The approach requires only a few hours of training without any additional sampling during fine-tuning. The final result, Zephyr-7B, sets the state-of-the-art on chat benchmarks for 7B parameter models, and requires no human annotation. In particular, results on MT-Bench show that Zephyr-7B surpasses Llama2-Chat-70B, the best open-access RLHF-based model. Code, models, data, and tutorials for the system are available at https://github.com/huggingface/alignment-handbook