906 research outputs found
The Circle of Meaning: From Translation to Paraphrasing and Back
The preservation of meaning between inputs and outputs is perhaps
the most ambitious and, often, the most elusive goal of systems
that attempt to process natural language. Nowhere is this goal of
more obvious importance than for the tasks of machine translation
and paraphrase generation. Preserving meaning between the input and
the output is paramount for both, the monolingual vs bilingual distinction
notwithstanding. In this thesis, I present a novel, symbiotic relationship
between these two tasks that I term the "circle of meaning''.
Today's statistical machine translation (SMT) systems require high
quality human translations for parameter tuning, in addition to
large bi-texts for learning the translation units. This parameter
tuning usually involves generating translations at different points
in the parameter space and obtaining feedback against human-authored
reference translations as to how good the translations. This feedback
then dictates what point in the parameter space should be explored
next. To measure this feedback, it is generally considered wise to have
multiple (usually 4) reference translations to avoid unfair penalization of translation
hypotheses which could easily happen given the large number of ways in which
a sentence can be translated from one language to another. However, this reliance on multiple reference translations
creates a problem since they are labor intensive and expensive to obtain.
Therefore, most current MT datasets only contain a single reference.
This leads to the problem of reference sparsity---the primary open problem
that I address in this dissertation---one that has a serious effect on the
SMT parameter tuning process.
Bannard and Callison-Burch (2005) were the first to provide a practical
connection between phrase-based statistical machine translation and paraphrase
generation. However, their technique is restricted to generating phrasal
paraphrases. I build upon their approach and augment a phrasal paraphrase
extractor into a sentential paraphraser with extremely broad coverage.
The novelty in this augmentation lies in the further strengthening of
the connection between statistical machine translation and paraphrase
generation; whereas Bannard and Callison-Burch only relied on SMT machinery
to extract phrasal paraphrase rules and stopped there, I take it a few
steps further and build a full English-to-English SMT system. This system
can, as expected, ``translate'' any English input sentence into a new English
sentence with the same degree of meaning preservation that exists in a bilingual
SMT system. In fact, being a state-of-the-art SMT system, it is able to generate
n-best "translations" for any given input sentence. This sentential
paraphraser, built almost entirely from existing SMT machinery, represents
the first 180 degrees of the circle of meaning.
To complete the circle, I describe a novel connection in the other direction.
I claim that the sentential paraphraser, once built in this fashion, can
provide a solution to the reference sparsity problem and, hence, be used
to improve the performance a bilingual SMT system. I discuss two different
instantiations of the sentential paraphraser and show several results that
provide empirical validation for this connection
ZETA - Zero-Trust Authentication: Relying on Innate Human Ability, not Technology
Reliable authentication requires the devices and
channels involved in the process to be trustworthy; otherwise
authentication secrets can easily be compromised. Given the
unceasing efforts of attackers worldwide such trustworthiness
is increasingly not a given. A variety of technical solutions,
such as utilising multiple devices/channels and verification
protocols, has the potential to mitigate the threat of untrusted
communications to a certain extent. Yet such technical solutions
make two assumptions: (1) users have access to multiple
devices and (2) attackers will not resort to hacking the human,
using social engineering techniques. In this paper, we propose
and explore the potential of using human-based computation
instead of solely technical solutions to mitigate the threat of
untrusted devices and channels. ZeTA (Zero Trust Authentication
on untrusted channels) has the potential to allow people to
authenticate despite compromised channels or communications
and easily observed usage. Our contributions are threefold:
(1) We propose the ZeTA protocol with a formal definition
and security analysis that utilises semantics and human-based
computation to ameliorate the problem of untrusted devices
and channels. (2) We outline a security analysis to assess
the envisaged performance of the proposed authentication
protocol. (3) We report on a usability study that explores the
viability of relying on human computation in this context
Latent Representation and Sampling in Network: Application in Text Mining and Biology.
In classical machine learning, hand-designed features are used for learning a mapping from raw data. However, human involvement in feature design makes the process expensive. Representation learning aims to learn abstract features directly from data without direct human involvement. Raw data can be of various forms. Network is one form of data that encodes relational structure in many real-world domains. Therefore, learning abstract features for network units is an important task. In this dissertation, we propose models for incorporating temporal information given as a collection of networks from subsequent time-stamps. The primary objective of our models is to learn a better abstract feature representation of nodes and edges in an evolving network. We show that the temporal information in the abstract feature improves the performance of link prediction task substantially. Besides applying to the network data, we also employ our models to incorporate extra-sentential information in the text domain for learning better representation of sentences. We build a context network of sentences to capture extra-sentential information. This information in abstract feature representation of sentences improves various text-mining tasks substantially over a set of baseline methods. A problem with the abstract features that we learn is that they lack interpretability. In real-life applications on network data, for some tasks, it is crucial to learn interpretable features in the form of graphical structures. For this we need to mine important graphical structures along with their frequency statistics from the input dataset. However, exact algorithms for these tasks are computationally expensive, so scalable algorithms are of urgent need. To overcome this challenge, we provide efficient sampling algorithms for mining higher-order structures from network(s). We show that our sampling-based algorithms are scalable. They are also superior to a set of baseline algorithms in terms of retrieving important graphical sub-structures, and collecting their frequency statistics. Finally, we show that we can use these frequent subgraph statistics and structures as features in various real-life applications. We show one application in biology and another in security. In both cases, we show that the structures and their statistics significantly improve the performance of knowledge discovery tasks in these domains
Automatic Paragraph Segmentation with Lexical and Prosodic Features
ComunicaciĆ³ presentada a la Interspeech 2016, celebrada per la International Speech Communication Association (ISCA) els dies 8 a 12 de septembre de 2016 a San Francisco (EUA).As long-form spoken documents become more ubiquitous in everyday life, so does the need for automatic discourse segmentation in spoken language processing tasks. Although previous work has focused on broad topic segmentation, detection of finer-grained discourse units, such as paragraphs, is highly desirable for presenting and analyzing spoken content. To better understand how different aspects of speech cue these subtle discourse transitions, we investigate automatic paragraph segmentation of TED talks. We build lexical and prosodic paragraph segmenters using Support Vector Machines, AdaBoost, and Long Short Term Memory (LSTM) recurrent neural networks. In general, we find that induced cue words and supra-sentential prosodic features outperform features based on topical coherence, syntactic form and complexity. However, our best performance is achieved by combining a wide range of individually weak lexical and prosodic features, with the sequence modelling LSTM generally outperforming the other classifiers by a large margin. Moreover, we find that models that allow lower level interactions between different feature types produce better results than treating lexical and prosodic contributions as separate, independent information sources.The second author is funded from the EUās Horizon 2020 Research and Innovation Programme under the GA H2020-RIA-645012 and the Spanish Ministry of Economy and Competitivity Juan de la Cierva program
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Computational Approaches to Assisting Patients\u27 Medical Comprehension from Electronic Health Records
Patient-centered care has been established as a fundamental approach to improve the quality of health care in a seminal report by the Institute of Medicine published at the start of the century. Improved access to health information and demand for greater transparency contributed to its move into the mainstream. Research has also demonstrated that actively involving patients in the management of their own health can lead to better outcomes, and potentially lower costs. However, despite the efforts in many areas of medicine to embrace patient-centered care, engaging patients is still considered a challenge. One of the barriers is the lack of effective tools to help patients understand their health conditions, options and their consequences.
Patient portals are now widely adopted by hospitals and other healthcare practices to provide patients with the capabilities to view their own Electronic Health Records. They are a rich resource of information for patients. However, the language in the records are generally difficult for patients without training in medicine to understand. Furthermore, the amount of information can often be overwhelming as well. In this work, we propose computational approaches to foster patient engagement from three aspects by exploiting the rich information in the medical records.
First, we design a framework to automatically generate health literacy instruments to measure a patient\u27s literacy levels. This framework exploits readily available large scale corpora to generate instruments in a commonly used test format. Second, we investigate methods that can determine the readability of complex documents such as health records. We propose to rank document readability, instead of assigning a grade level or a pre-defined difficulty category. Lastly, we examine the problem of finding targeted educational materials to facilitate patient comprehension of medical notes. We study methods to formulate effective queries from specialized and long clinical narratives. In addition, we propose a neural network based method to identify medical concepts that are important to patients.
The three aspects of this work address the issues of the overabundance and technical complexity of medical language in health records. We demonstrate that our approaches are effective with various experiments and evaluation metric
Deep Architectures for Visual Recognition and Description
In recent times, digital media contents are inherently of multimedia type, consisting of the form text, audio, image and video. Several of the outstanding computer Vision (CV) problems are being successfully solved with the help of modern Machine Learning (ML) techniques. Plenty of research work has already been carried out in the field of Automatic Image Annotation (AIA), Image Captioning and Video Tagging. Video Captioning, i.e., automatic description generation from digital video, however, is a different and complex problem altogether. This study compares various existing video captioning approaches available today and attempts their classification and analysis based on different parameters, viz., type of captioning methods (generation/retrieval), type of learning models employed, the desired output description length generated, etc. This dissertation also attempts to critically analyze the existing benchmark datasets used in various video captioning models and the evaluation metrics for assessing the final quality of the resultant video descriptions generated. A detailed study of important existing models, highlighting their comparative advantages as well as disadvantages are also included.
In this study a novel approach for video captioning on the Microsoft Video Description (MSVD) dataset and Microsoft Video-to-Text (MSR-VTT) dataset is proposed using supervised learning techniques to train a deep combinational framework, for achieving better quality video captioning via predicting semantic tags. We develop simple shallow CNN (2D and 3D) as feature extractors, Deep Neural Networks (DNNs and Bidirectional LSTMs (BiLSTMs) as tag prediction models and Recurrent Neural Networks (RNNs) (LSTM) model as the language model. The aim of the work was to provide an alternative narrative to generating captions from videos via semantic tag predictions and deploy simpler shallower deep model architectures with lower memory requirements as solution so that it is not very memory extensive and the developed models prove to be stable and viable options when the scale of the data is increased.
This study also successfully employed deep architectures like the Convolutional Neural Network (CNN) for speeding up automation process of hand gesture recognition and classification of the sign languages of the Indian classical dance form, āBharatnatyamā. This hand gesture classification is primarily aimed at 1) building a novel dataset of 2D single hand gestures belonging to 27 classes that were collected from (i) Google search engine (Google images), (ii) YouTube videos (dynamic and with background considered) and (iii) professional artists under staged environment constraints (plain backgrounds). 2) exploring the effectiveness of CNNs for identifying and classifying the single hand gestures by optimizing the hyperparameters, and 3) evaluating the impacts of transfer learning and double transfer learning, which is a novel concept explored for achieving higher classification accuracy
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