A Phrase Table without Phrases: Rank Encoding for Better Phrase

Abstract This paper describes the first steps towards a minimum-size phrase table implementation to be used for phrase-based statistical machine translation. The focus lies on the size reduction of target language data in a phrase table. Rank Encoding (REnc), a novel method for the compression of word-aligned target language in phrase tables is presented. Combined with Huffman coding a relative size reduction of 56 percent for target phrase words and alignment data is achieved when compared to bare Huffman coding without R-Enc. In the context of the complete phrase table the size reduction is 22 percent

Rethinking Data Augmentation for Low-Resource Neural Machine Translation: A Multi-Task Learning Approach

In the context of neural machine translation, data augmentation (DA) techniques may be used for generating additional training samples when the available parallel data are scarce. Many DA approaches aim at expanding the support of the empirical data distribution by generating new sentence pairs that contain infrequent words, thus making it closer to the true data distribution of parallel sentences. In this paper, we propose to follow a completely different approach and present a multi-task DA approach in which we generate new sentence pairs with transformations, such as reversing the order of the target sentence, which produce unfluent target sentences. During training, these augmented sentences are used as auxiliary tasks in a multi-task framework with the aim of providing new contexts where the target prefix is not informative enough to predict the next word. This strengthens the encoder and forces the decoder to pay more attention to the source representations of the encoder. Experiments carried out on six low-resource translation tasks show consistent improvements over the baseline and over DA methods aiming at extending the support of the empirical data distribution. The systems trained with our approach rely more on the source tokens, are more robust against domain shift and suffer less hallucinations.Work funded by the European Union’s Horizon 2020 research and innovation programme under grant agreement number 825299, project Global Under-Resourced Media Translation (GoURMET); and by Generalitat Valenciana through project GV/2021/064. The computational resources used for the experiments were funded by the European Regional Development Fund through project IDIFEDER/2020/003

Architecture for Efficient String Dictionaries in E-Learning

E-Learning is a response to the new educational needs of society and an important development in Information and Communication Technologies. However, this trend presents many challenges, such as the lack of an architecture that allows a unified management of heterogeneous string dictionaries required by all the users of e-learning environments, which we face in this paper. We mean the string dictionaries needed in information retrieval, content development, “key performance indicators” generation and course management applications. As an example, our approach can deal with different indexation dictionaries required by the course contents and the different online forums that generate a huge number of messages with an unordered structure and a great variety of topics. Our architecture will generate an only dictionary that is shared by all the stakeholders involved in the e-learning process.This work was supported in part by the Spanish Ministry of Economy and Competitiveness (MINECO) under Project SEQUOIA-UA (TIN2015-63502-C3-3-R), Project RESCATA (TIN2015-65100-R) and Project PROMETEO/2018/089; and in part by the Spanish Research Agency (AEI) and the European Regional Development Fund (FEDER) under Project CloudDriver4Industry (TIN2017-89266-R)

Non-Fluent Synthetic Target-Language Data Improve Neural Machine Translation

When the amount of parallel sentences available to train a neural machine translation is scarce, a common practice is to generate new synthetic training samples from them. A number of approaches have been proposed to produce synthetic parallel sentences that are similar to those in the parallel data available. These approaches work under the assumption that non-fluent target-side synthetic training samples can be harmful and may deteriorate translation performance. Even so, in this paper we demonstrate that synthetic training samples with non-fluent target sentences can improve translation performance if they are used in a multilingual machine translation framework as if they were sentences in another language. We conducted experiments on ten low-resource and four high-resource translation tasks and found out that this simple approach consistently improves translation performance as compared to state-of-the-art methods for generating synthetic training samples similar to those found in corpora. Furthermore, this improvement is independent of the size of the original training corpus, the resulting systems are much more robust against domain shift and produce less hallucinations.This paper is part of the R+D+i project PID2021-127999NB-I00 funded by the Spanish Ministry of Science and Innovation (MCIN), the Spanish Research Agency (AEI/10.13039/501100011033) and the European Regional Development Fund A way to make Europe. The computational resources used were funded by the European Regional Development Fund through project ID-IFEDER/2020/003

Generalized biwords for bitext compression and translation spotting

Large bilingual parallel texts (also known as bitexts) are usually stored in a compressed form, and previous work has shown that they can be more efficiently compressed if the fact that the two texts are mutual translations is exploited. For example, a bitext can be seen as a sequence of biwords —pairs of parallel words with a high probability of co-occurrence— that can be used as an intermediate representation in the compression process. However, the simple biword approach described in the literature can only exploit one-to-one word alignments and cannot tackle the reordering of words. We therefore introduce a generalization of biwords which can describe multi-word expressions and reorderings. We also describe some methods for the binary compression of generalized biword sequences, and compare their performance when different schemes are applied to the extraction of the biword sequence. In addition, we show that this generalization of biwords allows for the implementation of an efficient algorithm to look on the compressed bitext for words or text segments in one of the texts and retrieve their counterpart translations in the other text —an application usually referred to as translation spotting— with only some minor modifications in the compression algorithm.This work has been supported by the Spanish Government through projects TIN2009-14009-C02-01 and TIN2009-14009-C02-02, and by the Millennium Institute for Cell Dynamics and Biotechnology (grant ICM P05-001-F)