388 research outputs found
Paradigm Completion for Derivational Morphology
The generation of complex derived word forms has been an overlooked problem
in NLP; we fill this gap by applying neural sequence-to-sequence models to the
task. We overview the theoretical motivation for a paradigmatic treatment of
derivational morphology, and introduce the task of derivational paradigm
completion as a parallel to inflectional paradigm completion. State-of-the-art
neural models, adapted from the inflection task, are able to learn a range of
derivation patterns, and outperform a non-neural baseline by 16.4%. However,
due to semantic, historical, and lexical considerations involved in
derivational morphology, future work will be needed to achieve performance
parity with inflection-generating systems.Comment: EMNLP 201
Marrying Universal Dependencies and Universal Morphology
The Universal Dependencies (UD) and Universal Morphology (UniMorph) projects
each present schemata for annotating the morphosyntactic details of language.
Each project also provides corpora of annotated text in many languages - UD at
the token level and UniMorph at the type level. As each corpus is built by
different annotators, language-specific decisions hinder the goal of universal
schemata. With compatibility of tags, each project's annotations could be used
to validate the other's. Additionally, the availability of both type- and
token-level resources would be a boon to tasks such as parsing and homograph
disambiguation. To ease this interoperability, we present a deterministic
mapping from Universal Dependencies v2 features into the UniMorph schema. We
validate our approach by lookup in the UniMorph corpora and find a
macro-average of 64.13% recall. We also note incompatibilities due to paucity
of data on either side. Finally, we present a critical evaluation of the
foundations, strengths, and weaknesses of the two annotation projects.Comment: UDW1
Automatic Restoration of Diacritics for Igbo Language
Igbo is a low-resource African language with orthographic and tonal diacritics, which capture distinctions between words that are important for both meaning and pronunciation, and hence of potential value for a range of language processing tasks. Such diacritics, however, are often largely absent from the electronic texts we might want to process, or assemble into corpora, and so the need arises for effective methods for automatic diacritic restoration for Igbo. In this paper, we experiment using an Igbo bible corpus, which is extensively marked for vowel distinctions, and partially for tonal distinctions, and attempt the task of reinstating these diacritics when they have been deleted. We investigate a number of word-level diacritic restoration methods, based on n-grams, under a closed-world assumption, achieving an accuracy of 98.83 % with our most effective method
Assessing the contribution of shallow and deep knowledge sources for word sense disambiguation
Corpus-based techniques have proved to be very beneficial in the development of efficient and accurate approaches to word sense disambiguation (WSD) despite the fact that they generally represent relatively shallow knowledge. It has always been thought, however, that WSD could also benefit from deeper knowledge sources. We describe a novel approach to WSD using inductive logic programming to learn theories from first-order logic representations that allows corpus-based evidence to be combined with any kind of background knowledge. This approach has been shown to be effective over several disambiguation tasks using a combination of deep and shallow knowledge sources. Is it important to understand the contribution of the various knowledge sources used in such a system. This paper investigates the contribution of nine knowledge sources to the performance of the disambiguation models produced for the SemEval-2007 English lexical sample task. The outcome of this analysis will assist future work on WSD in concentrating on the most useful knowledge sources
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