Gina Bustamante


2020

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Efficient Strategies for Hierarchical Text Classification: External Knowledge and Auxiliary Tasks
Kervy Rivas Rojas | Gina Bustamante | Arturo Oncevay | Marco Antonio Sobrevilla Cabezudo
Proceedings of the 58th Annual Meeting of the Association for Computational Linguistics

In hierarchical text classification, we perform a sequence of inference steps to predict the category of a document from top to bottom of a given class taxonomy. Most of the studies have focused on developing novels neural network architectures to deal with the hierarchical structure, but we prefer to look for efficient ways to strengthen a baseline model. We first define the task as a sequence-to-sequence problem. Afterwards, we propose an auxiliary synthetic task of bottom-up-classification. Then, from external dictionaries, we retrieve textual definitions for the classes of all the hierarchy’s layers, and map them into the word vector space. We use the class-definition embeddings as an additional input to condition the prediction of the next layer and in an adapted beam search. Whereas the modified search did not provide large gains, the combination of the auxiliary task and the additional input of class-definitions significantly enhance the classification accuracy. With our efficient approaches, we outperform previous studies, using a drastically reduced number of parameters, in two well-known English datasets.

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No Data to Crawl? Monolingual Corpus Creation from PDF Files of Truly low-Resource Languages in Peru
Gina Bustamante | Arturo Oncevay | Roberto Zariquiey
Proceedings of the 12th Language Resources and Evaluation Conference

We introduce new monolingual corpora for four indigenous and endangered languages from Peru: Shipibo-konibo, Ashaninka, Yanesha and Yine. Given the total absence of these languages in the web, the extraction and processing of texts from PDF files is relevant in a truly low-resource language scenario. Our procedure for monolingual corpus creation considers language-specific and language-agnostic steps, and focuses on educational PDF files with multilingual sentences, noisy pages and low-structured content. Through an evaluation based on language modelling and character-level perplexity on a subset of manually extracted sentences, we determine that our method allows the creation of clean corpora for the four languages, a key resource for natural language processing tasks nowadays.

2019

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CSI Peru News: finding the culprit, victim and location in news articles
Gina Bustamante | Arturo Oncevay
Proceedings of the 2019 Workshop on Widening NLP

We introduce a shift on the DS method over the domain of crime-related news from Peru, attempting to find the culprit, victim and location of a crime description from a RE perspective. Obtained results are highly promising and show that proposed modifications are effective in non-traditional domains.