36 research outputs found
A Comparison of Unsupervised Methods for Ad hoc Cross-Lingual Document Retrieval
We address the problem of linking related documents across languages in a multilingual collection. We evaluate three diverse unsupervised methods to represent and compare documents: (1) multilingual topic model; (2) cross-lingual document embeddings; and (3) Wasserstein distance. We test the performance of these methods in retrieving news articles in Swedish that are known to be related to a given Finnish article. The results show that ensembles of the methods outperform the stand-alone methods, suggesting that they capture complementary characteristics of the documents.Peer reviewe
Adversarial Training in Affective Computing and Sentiment Analysis: Recent Advances and Perspectives
Over the past few years, adversarial training has become an extremely active
research topic and has been successfully applied to various Artificial
Intelligence (AI) domains. As a potentially crucial technique for the
development of the next generation of emotional AI systems, we herein provide a
comprehensive overview of the application of adversarial training to affective
computing and sentiment analysis. Various representative adversarial training
algorithms are explained and discussed accordingly, aimed at tackling diverse
challenges associated with emotional AI systems. Further, we highlight a range
of potential future research directions. We expect that this overview will help
facilitate the development of adversarial training for affective computing and
sentiment analysis in both the academic and industrial communities
Multi-Vector Models with Textual Guidance for Fine-Grained Scientific Document Similarity
We present a new scientific document similarity model based on matching
fine-grained aspects of texts. To train our model, we exploit a
naturally-occurring source of supervision: sentences in the full-text of papers
that cite multiple papers together (co-citations). Such co-citations not only
reflect close paper relatedness, but also provide textual descriptions of how
the co-cited papers are related. This novel form of textual supervision is used
for learning to match aspects across papers. We develop multi-vector
representations where vectors correspond to sentence-level aspects of
documents, and present two methods for aspect matching: (1) A fast method that
only matches single aspects, and (2) a method that makes sparse multiple
matches with an Optimal Transport mechanism that computes an Earth Mover's
Distance between aspects. Our approach improves performance on document
similarity tasks in four datasets. Further, our fast single-match method
achieves competitive results, paving the way for applying fine-grained
similarity to large scientific corpora. Code, data, and models available at:
https://github.com/allenai/aspireComment: NAACL 2022 camera-read
Rationalizing Text Matching: Learning Sparse Alignments via Optimal Transport
Selecting input features of top relevance has become a popular method for
building self-explaining models. In this work, we extend this selective
rationalization approach to text matching, where the goal is to jointly select
and align text pieces, such as tokens or sentences, as a justification for the
downstream prediction. Our approach employs optimal transport (OT) to find a
minimal cost alignment between the inputs. However, directly applying OT often
produces dense and therefore uninterpretable alignments. To overcome this
limitation, we introduce novel constrained variants of the OT problem that
result in highly sparse alignments with controllable sparsity. Our model is
end-to-end differentiable using the Sinkhorn algorithm for OT and can be
trained without any alignment annotations. We evaluate our model on the
StackExchange, MultiNews, e-SNLI, and MultiRC datasets. Our model achieves very
sparse rationale selections with high fidelity while preserving prediction
accuracy compared to strong attention baseline models.Comment: To appear at ACL 202
Multiview Learning with Sparse and Unannotated data.
PhD ThesisObtaining annotated training data for supervised learning, is a bottleneck in many
contemporary machine learning applications. The increasing prevalence of multi-modal
and multi-view data creates both new opportunities for circumventing this issue, and
new application challenges. In this thesis we explore several approaches to alleviating
annotation issues in multi-view scenarios.
We start by studying the problem of zero-shot learning (ZSL) for image recognition,
where class-level annotations for image recognition are eliminated by transferring information
from text modality instead. We next look at cross-modal matching, where
paired instances across views provide the supervised label information for learning. We
develop methodology for unsupervised and semi-supervised learning of pairing, thus
eliminating the need for annotation requirements.
We rst apply these ideas to unsupervised multi-view matching in the context of
bilingual dictionary induction (BLI), where instances are words in two languages and
nding a correspondence between the words produces a cross-lingual word translation
model. We then return to vision and language and look at learning unsupervised pairing
between images and text. We will see that this can be seen as a limiting case of ZSL
where text-image pairing annotation requirements are completely eliminated.
Overall these contributions in multi-view learning provide a suite of methods for
reducing annotation requirements: both in conventional classi cation and cross-view
matching settings
Preference-based Representation Learning for Collections
In this thesis, I make some contributions to the development of representation learning in the setting of external constraints and noisy supervision. A setting of external constraints refers to the scenario in which the learner is forced to output a latent representation of the given data points while enforcing some particular conditions. These conditions can be geometrical constraints, for example forcing the vector embeddings to be close to each other based on a particular relations, or forcing the embedding vectors to lie in a particular manifold, such as the manifold of vectors whose elements sum to 1, or even more complex constraints. The objects of interest in this thesis are elements of a collection X in an abstract space that is endowed with a similarity function which quantifies how similar two objects are. A collection is defined as a set of items in which the order is ignored but the multiplicity is relevant. Various types of collections are used as inputs or outputs in the machine learning field. The most common are perhaps sequences and sets.
Besides studying representation learning approaches in presence of external constraints, in this thesis we tackle the case in which the evaluation of this similarity function is not directly possible. In recent years, the machine learning setting of having only binary answers to some comparisons for tuples of elements has gained interest. Learning good representations from a scenario in which a clear distance information cannot be obtained is of fundamental importance. This problem is opposite to the standard machine learning setting where the similarity function between elements can be directly evaluated. Moreover, we tackle the case in which the learner is given noisy supervision signals, with a certain probability for the label to be incorrect. Another research question that was studied in this thesis is how to assess the quality of the learned representations and how a learner can convey the uncertainty about this representation.
After the introductory Chapter 1, the thesis is structured in three main parts. In the first part, I present the results of representation learning based on data points that are sequences. The focus in this part is on sentences and permutations, particular types of sequences. The first contribution of this part consists in enforcing analogical relations between sentences and the second is learning appropriate representations for permutations, which are particular mathematical objects, while using neural networks. The second part of this thesis tackles the question of learning perceptual embeddings from binary and noisy comparisons. In machine learning, this problem is referred as ordinal embedding problem. This part contains two chapters which elaborate two different aspects of the problem: appropriately conveying the uncertainty of the representation and learning the embeddings from aggregated and noisy feedback. Finally the third part of the thesis, contains applications of the findings of the previous part, namely unsupervised alignment of clouds of embedding vectors and entity set extension