13 research outputs found
Comparison of Different Orthographies for Machine Translation of Under-Resourced Dravidian Languages
Under-resourced languages are a significant challenge for statistical approaches to machine translation, and recently it has been shown that the usage of training data from closely-related languages can improve machine translation quality of these languages. While languages within the same language family share many properties, many under-resourced languages are written in their own native script, which makes taking advantage of these language similarities difficult. In this paper, we propose to alleviate the problem of different scripts by transcribing the native script into common representation i.e. the Latin script or the International Phonetic Alphabet (IPA). In particular, we compare the difference between coarse-grained transliteration to the Latin script and fine-grained IPA transliteration. We performed experiments on the language pairs English-Tamil, English-Telugu, and English-Kannada translation task. Our results show improvements in terms of the BLEU, METEOR and chrF scores from transliteration and we find that the transliteration into the Latin script outperforms the fine-grained IPA transcription
A Sentiment Analysis Dataset for Code-Mixed Malayalam-English
There is an increasing demand for sentiment analysis of text from social
media which are mostly code-mixed. Systems trained on monolingual data fail for
code-mixed data due to the complexity of mixing at different levels of the
text. However, very few resources are available for code-mixed data to create
models specific for this data. Although much research in multilingual and
cross-lingual sentiment analysis has used semi-supervised or unsupervised
methods, supervised methods still performs better. Only a few datasets for
popular languages such as English-Spanish, English-Hindi, and English-Chinese
are available. There are no resources available for Malayalam-English
code-mixed data. This paper presents a new gold standard corpus for sentiment
analysis of code-mixed text in Malayalam-English annotated by voluntary
annotators. This gold standard corpus obtained a Krippendorff's alpha above 0.8
for the dataset. We use this new corpus to provide the benchmark for sentiment
analysis in Malayalam-English code-mixed texts
Corpus Creation for Sentiment Analysis in Code-Mixed Tamil-English Text
Understanding the sentiment of a comment from a video or an image is an
essential task in many applications. Sentiment analysis of a text can be useful
for various decision-making processes. One such application is to analyse the
popular sentiments of videos on social media based on viewer comments. However,
comments from social media do not follow strict rules of grammar, and they
contain mixing of more than one language, often written in non-native scripts.
Non-availability of annotated code-mixed data for a low-resourced language like
Tamil also adds difficulty to this problem. To overcome this, we created a gold
standard Tamil-English code-switched, sentiment-annotated corpus containing
15,744 comment posts from YouTube. In this paper, we describe the process of
creating the corpus and assigning polarities. We present inter-annotator
agreement and show the results of sentiment analysis trained on this corpus as
a benchmark
Language Modelling with Pixels
Language models are defined over a finite set of inputs, which creates a
vocabulary bottleneck when we attempt to scale the number of supported
languages. Tackling this bottleneck results in a trade-off between what can be
represented in the embedding matrix and computational issues in the output
layer. This paper introduces PIXEL, the Pixel-based Encoder of Language, which
suffers from neither of these issues. PIXEL is a pretrained language model that
renders text as images, making it possible to transfer representations across
languages based on orthographic similarity or the co-activation of pixels.
PIXEL is trained to reconstruct the pixels of masked patches, instead of
predicting a distribution over tokens. We pretrain the 86M parameter PIXEL
model on the same English data as BERT and evaluate on syntactic and semantic
tasks in typologically diverse languages, including various non-Latin scripts.
We find that PIXEL substantially outperforms BERT on syntactic and semantic
processing tasks on scripts that are not found in the pretraining data, but
PIXEL is slightly weaker than BERT when working with Latin scripts.
Furthermore, we find that PIXEL is more robust to noisy text inputs than BERT,
further confirming the benefits of modelling language with pixels.Comment: work in progres
Character-level and syntax-level models for low-resource and multilingual natural language processing
There are more than 7000 languages in the world, but only a small portion of them benefit from Natural Language Processing resources and models. Although languages generally present different characteristics, “cross-lingual bridges” can be exploited, such as transliteration signals and word alignment links. Such information, together with the availability of multiparallel corpora and the urge to overcome language barriers, motivates us to build models that represent more of the world’s languages.
This thesis investigates cross-lingual links for improving the processing of low-resource languages with language-agnostic models at the character and syntax level. Specifically, we propose to (i) use orthographic similarities and transliteration between Named Entities and rare words in different languages to improve the construction of Bilingual Word Embeddings (BWEs) and named entity resources, and (ii) exploit multiparallel corpora for projecting labels from high- to low-resource languages, thereby gaining access to weakly supervised processing methods for the latter.
In the first publication, we describe our approach for improving the translation of rare words and named entities for the Bilingual Dictionary Induction (BDI) task, using orthography and transliteration information. In our second work, we tackle BDI by enriching BWEs with orthography embeddings and a number of other features, using our classification-based system to overcome script differences among languages. The third publication describes cheap cross-lingual signals that should be considered when building mapping approaches for BWEs since they are simple to extract, effective for bootstrapping the mapping of BWEs, and overcome the failure of unsupervised methods. The fourth paper shows our approach for extracting a named entity resource for 1340 languages, including very low-resource languages from all major areas of linguistic diversity. We exploit parallel corpus statistics and transliteration models and obtain improved performance over prior work. Lastly, the fifth work models annotation projection as a graph-based label propagation problem for the part of speech tagging task. Part of speech models trained on our labeled sets outperform prior work for low-resource languages like Bambara (an African language spoken in Mali), Erzya (a Uralic language spoken in Russia’s Republic of Mordovia), Manx (the Celtic language of the Isle of Man), and Yoruba (a Niger-Congo language spoken in Nigeria and surrounding countries)