On the Limitations of Unsupervised Bilingual Dictionary Induction

Anders Søgaard, Sebastian Ruder, Ivan Vulic

    59 Citations (Scopus)

    Abstract

    Unsupervised machine translation—i.e.,not assuming any cross-lingual supervisionsignal, whether a dictionary, translations,or comparable corpora—seems impossible,but nevertheless, Lample et al.(2018a) recently proposed a fully unsupervisedmachine translation (MT) model.The model relies heavily on an adversarial,unsupervised alignment of word embeddingspaces for bilingual dictionary induction(Conneau et al., 2018), which weexamine here. Our results identify the limitationsof current unsupervised MT: unsupervisedbilingual dictionary inductionperforms much worse on morphologicallyrich languages that are not dependent marking,when monolingual corpora from differentdomains or different embedding algorithmsare used. We show that a simpletrick, exploiting a weak supervision signalfrom identical words, enables more robustinduction, and establish a near-perfectcorrelation between unsupervised bilingualdictionary induction performance and a previouslyunexplored graph similarity metric
    Original languageEnglish
    Title of host publicationProceedings of the 56th Annual Meeting of the Association for Computational Linguistics : (Long papers)
    PublisherAssociation for Computational Linguistics
    Publication date2018
    Pages778–788
    Publication statusPublished - 2018
    Event 56th Annual Meeting of the Association for Computational Linguistics - System Demonstrations - Melbourne, Australia
    Duration: 15 Jul 201820 Jul 2018

    Conference

    Conference 56th Annual Meeting of the Association for Computational Linguistics - System Demonstrations
    Country/TerritoryAustralia
    CityMelbourne
    Period15/07/201820/07/2018

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