Notes from EMNLP 2022
Last week I was at EMNLP in Abu Dhabi. Besides losing my passport and figuring out what to do on such an occasion (many thanks to the personnel of the Czech embassy in Abu Dhabi), I had plenty of interesting conversations and saw many interesting posters. When I was at my first NLP conference 8 years ago, I was amazed by the papers presented at the conference and returned with a long list of ideas of what I should try in my research. The older I get, the less excited I am about the papers (or was everything already on arXiv?), and the more I enjoy talking with people at the conference. So, even though nothing was particularly breathtaking, there were undoubtedly many papers that deserved attention. Here is my random and incomplete list of what I found noteworthy.
WMT Metrics Task
The best machine translation evaluation metrics are still the best choice. This year’s winners are Google’s MetricX XXL (finetuned mT5, but they did not publish any details) and a new version of COMET (with better multi-task learning). The good news is that the metrics are much better on the segment level. The bad news is that they still have problems with numbers and named entities (which was the biggest problem of our Czech-Ukrainian MT). Reference-free metrics are better than the BLEU score.
WMT Sign language translation task
WMT this year hosted the sign language translation task. It is a great initiative, but I was quite surprised by how poor the automatic systems are. The best systems translating from video to written language got around 2 points out of 100 in human evaluation (compared to 88 points of human baseline), and 0.6 BLEU points in automatic evaluation. (Edit: Originally, I had these numbers wrong. Thanks, Leftheris Avramidis for point it out.)
Subword-Delimited Downsampling for Better Character-Level Translation
A paper from the University of Groningen extends our work on character-level machine translation. In the architecture that we proposed, we reused a 2017 idea of processing characters with a CNN and downsample the state sequence to latent states that roughly correspond to words. This gets tricky on the decoder side because the hidden state sequence needs to be upsampled to characters again. We originally used a fixed downsampling step, but here they downsample the states by subwords. In this way, they manage to match the quality of the subword-based models.
Chunk-based Nearest Neighbor Machine Translation
Nearest neighbor machine translation is a non-parametric extension of neural MT models. Instead of making the usual output projection, it searches a database of pairs of decoder hidden states and matching output words. Then, it decides the output word based on the nearest neighbors in the database. It works particularly well for domain adaptation. However, the nearest neighbor search is much slower than the usual output projection. This paper has a solution: we do not have to retrieve single words matching the decoder states, but we can retrieve longer chunks. It sounds easy; however, it requires clever tricks to decide what the chunks should be.
The (Undesired) Attenuation of Human Biases by Multilinguality
Folks from Saarbrücken and Bologna played around with word embedding association tests and multilingual representation models. They study how non-moral cultural values are encoded in the embeddings (e.g., if some insect species are considered disgusting or flower species considered beautiful). They created a multilingual version of a word assiation that datasets that is unlike related work not a translation of the US-English one and performed the experiments on that. The paper concludes that static embeddings exhibit more cultural biases than contextual ones, and multilingual models also exhibit fewer biases than monolingual ones. However, in this particular case, we cannot say if the biases are good or bad; I would even argue that it is a good thing if models could grasp cultures associated with particular languages.
Calibrating Zero-shot Cross-lingual (Un-)structured Predictions
A paper from Johns Hopkins University studies model calibration during cross-lingual transfer. A model is well calibrated when if it predicts something with X% probability, it will be approximately in X% cases correct. This is, however, not often the case because neural models tend to be overconfident. During zero-shot language transfer (we train the model in one language and use it in another one), this gets even worse. The good news is that calibrating the model in the source language (using temperature scaling or Gaussian process calibration) helps in the target language too.
Don’t Stop Fine-Tuning: On Training Regimes for Few-Shot Cross-Lingual Transfer with Multilingual Language Models
A paper from Würzburg and Cambridge introduces a recipe for few-shot cross-lingual transfer. In this specific setup, you have a reasonably large task-specific dataset for one language but only a very small one (in this case, 100 instances) for a language in which you want to apply the model. The protocol the paper sees as the most promising one is 1) finetune on source language only, 2) mix source and target language and keep validating in the source language. The big advantage of this approach is that we do not need a validation set in the target language (which would be a weird assumption, if we had it, we could use it for finetuning).
Bloom Library: Multimodal Datasets in 300+ Languages for a Variety of Downstream Tasks
It has nothing in common with the multilingual Bloom model. This Bloom is a multilingual dataset with book translation in more than 300 languages, with various source languages, and with all books translated only to some languages. The dataset is also accompanied by images. They suggest some tasks like multilingual visual storytelling or image captioning. When I briefly looked at the dataset, my impression was that a large part of the stories is actually religions, which makes the dataset a little domain-specific.
Why is Winoground Hard? Investigating Failures in Visuolinguistic Compositionality
A group from the University of Texas in Austin tries to debunk why current models tend to fail on the Winoground challenge. Winoground is a challenge set for language-vision models: for two images and two captions, the model is supposed to tell which caption belongs to which image. It is tricky because the captions are composed of the same words in a different order. Thus, the models need not only to match objects with words but also to understand the structure of both the sentence and the image. The general opinion is that the models often fail because they do not capture the structure well. In this paper, they partially argue against this. They carefully labeled the test dataset and spotted several problematic phenomena: idioms (non-compositional phrases), unusual (=weird) texts, unusual (=weird images), visually difficult (even for humans), requiring complex reasoning. Using these labels, they show that problem is not that the models do not understand word order in general; they mostly fail in tricky situations.
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@misc{libovicky2022blog1221,
author = "Jindřich Libovický",
title = "Jindřich's Blog -- Notes from EMNLP 2022",
year = "2022",
month = dec,
url = "https://jlibovicky.github.io/2022/12/21/Notes-from-EMNLP",
note = "Online, Accessed: 05.12. 2024"
}