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João Graça

dblp:99/2806 · DBLP profile ↗
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21ranked-venue papers
5as first author
1since 2021 · last 2021
—ORCID · none

Domains — the database's venue-derived domains; a paper can count in several

Artificial intelligence and machine learning · 19 · 5 first-authorSystems, architecture and hardware · 1Databases, data management, data science and information retrieval · 1 · 1 since 2021

Expertise — from the expertise taxonomy: the topics of the expert's papers under the CCF categories. A weight counts papers with recency: 1 for a paper about the topic, 0.3 when the topic is its context, halved every five years.

Artificial intelligence
9 papers
Information extraction and text analysis · 34% Probabilistic and Bayesian machine learning · 28% Machine translation · 25%
Theoretical computer science
1 paper
Algorithms and data structures · 100%

Topics — the 18 heaviest of 20, each with the papers that count most for it

TopicWeightPapersLastEvidence papers
Natural language and speech › Information extraction and text analysis › sequence labeling
part-of-speech tagging
0.222012
Wiki-ly Supervised Part-of-Speech Tagging · EMNLP-CoNLL 2012
Posterior vs Parameter Sparsity in Latent Variable Models · NIPS 2009
Machine learning › Probabilistic and Bayesian machine learning › statistical inference › bayesian inference › approximate bayesian inference
posterior regularization
0.222010
Posterior Regularization for Structured Latent Variable Models · J. Mach. Learn. Res. 2010
Posterior vs Parameter Sparsity in Latent Variable Models · NIPS 2009
Machine learning › Probabilistic and Bayesian machine learning › structured models
latent variable model
0.222009
Posterior vs Parameter Sparsity in Latent Variable Models · NIPS 2009
Expectation Maximization and Posterior Constraints · NIPS 2007
Natural language and speech › Machine translation › statistical machine translation
word alignment
0.222008
Better Alignments = Better Translations? · ACL 2008
Expectation Maximization and Posterior Constraints · NIPS 2007
Natural language and speech › Machine translation › statistical machine translation
phrase-based translation
0.112012
Entropy-based Pruning for Phrase-based Machine Translation · EMNLP-CoNLL 2012
Machine learning › Efficient and distributed learning › model compression
pruning
0.112012
Entropy-based Pruning for Phrase-based Machine Translation · EMNLP-CoNLL 2012
Natural language and speech › Information extraction and text analysis › syntactic parsing
dependency parsing
0.112011
Posterior Sparsity in Unsupervised Dependency Parsing · J. Mach. Learn. Res. 2011
Natural language and speech › Information extraction and text analysis
morphological analysis
0.112011
Universal Morphological Analysis using Structured Nearest Neighbor Prediction · EMNLP 2011
Natural language and speech › Information extraction and text analysis › morphological analysis
morphological tagging
0.112011
Universal Morphological Analysis using Structured Nearest Neighbor Prediction · EMNLP 2011
Natural language and speech › Information extraction and text analysis › syntactic parsing › dependency parsing
unsupervised dependency parsing
0.112011
Posterior Sparsity in Unsupervised Dependency Parsing · J. Mach. Learn. Res. 2011
Machine learning › Probabilistic and Bayesian machine learning › structured models › latent variable model
latent structure discovery
0.112010
Posterior Regularization for Structured Latent Variable Models · J. Mach. Learn. Res. 2010
Natural language and speech › Machine translation
statistical machine translation
0.122008
Expectation Maximization and Posterior Constraints · NIPS 2007
Better Alignments = Better Translations? · ACL 2008
Machine learning › Probabilistic and Bayesian machine learning › statistical inference › parameter estimation
expectation-maximization
0.112007
Expectation Maximization and Posterior Constraints · NIPS 2007
Machine learning › Learning paradigms
weakly supervised learning
0.012012
Wiki-ly Supervised Part-of-Speech Tagging · EMNLP-CoNLL 2012
Algorithms and data structures › similarity search
nearest neighbor search
0.012011
Universal Morphological Analysis using Structured Nearest Neighbor Prediction · EMNLP 2011
Machine learning › Probabilistic and Bayesian machine learning › statistical inference › parameter estimation › expectation-maximization
variational EM
0.012009
Posterior vs Parameter Sparsity in Latent Variable Models · NIPS 2009
Machine learning › Probabilistic and Bayesian machine learning › probabilistic inference › approximate inference
variational inference
0.012009
Posterior vs Parameter Sparsity in Latent Variable Models · NIPS 2009
Data mining
clustering
0.012007
Expectation Maximization and Posterior Constraints · NIPS 2007

Methods — techniques the papers use, named apart from their topics

posterior regularization · 0.3expectation-maximization · 0.2entropy-based pruning · 0.1posterior sparsity · 0.1nearest-neighbor prediction · 0.1nearest neighbor prediction · 0.1variational bayes · 0.1dirichlet prior · 0.1
YearPublicationVenuePosition
2021 Knowledge Sharing in Catholic Organizations: A Fuzzy-Set Qualitative Comparative Analysis
abstract
This study examines knowledge sharing in Catholic organizations. The authors adopt Schein's organizational culture theory that facilitates, or inhibits, knowledge sharing in organizations. Thus, they address the phenomenon at the three levels: the artifacts, the norms and values, and the underlying assumptions. Considering the chosen settings, they study the contributions of individuals having taken vows, the organizational rituals, the significance, and the sense of community perceived by the organizational members. Data were gathered using a survey and were analyzed by using a fuzzy-set qualitative comparative analysis. The study provides the causal configurations of conditions that lead to tacit, explicit, and total knowledge sharing. They also offer the causal configurations of conditions that lead to the absence of each kind of knowledge sharing. Given that the qualitative results cannot be generalized, the study can still be replicated in organizations without restrictions.
Carla Curado, João Graça, Mírian Oliveira, Alexandra Fernandes
Int. J. Knowl. Manag.2
2020 Project MAIA: Multilingual AI Agent Assistant
abstract
This paper presents the Multilingual Artificial Intelligence Agent Assistant (MAIA), a project led by Unbabel with the collaboration of CMU, INESC-ID and IT Lisbon. MAIA will employ cutting-edge machine learning and natural language processing technologies to build multilingual AI agent assistants, eliminating language barriers. MAIA’s translation layer will empower human agents to provide customer support in real-time, in any language, with human quality.
André F. T. Martins, João Graça, Paulo Dimas, Helena Moniz, Graham Neubig
EAMT2
2017 The INTERACT Project and Crisis MT
Sharon O'Brien, Chao-Hong Liu, Andy Way, João Graça, Helena Moniz, Ellie Kemp, Rebecca Petras
MTSummit (2)4
2015 Live demonstration: A CMOS ASIC for precise reading of a Magnetoresistive sensor array for NDT
abstract
Non-destructive testing (NDT) based on eddy currents (EC) is commonly used to detect defects in conductive materials. Usually the system includes an emitter coil, and one receiver coil or one Magnetoresistive (MR) sensor. In this work we added an interface ASIC that pre-amplifies and filters the signal from an array of MR sensors. This demo will present a new version based on the work presented at the ECNDT 2014 conference with a paper entitled “A CMOS ASIC for Precise Reading of a Magnetoresistive Sensor Array for NDT”. Since this is an on-going work, improvements have been made, namely the reduction of the system thermal noise to 30 nV/√Hz, the development of a multigain amplifier and the application of the same concept and circuit to a multichannel parallel signal acquisition system. Detection of surface and buried defects will be demonstrated in different material mock-ups.
Diogo Miguel Caetano, Moisés Simões Piedade, João Graça, Jorge R. Fernandes, Luis S. Rosado, Tiago L. Costa
ISCAS3
2012 Wiki-ly Supervised Part-of-Speech Tagging
João Graça, Ben Taskar
EMNLP-CoNLL2
2012 Entropy-based Pruning for Phrase-based Machine Translation
Wang Ling, João Graça, Isabel Trancoso, Alan W. Black
EMNLP-CoNLL2
2012 A PropBank for Portuguese: the CINTIL-PropBank
António Branco, Catarina Carvalheiro, Sílvia Pereira, Sara Silveira, João Silva 0004, Sérgio Castro, João Graça
LREC7
2011 Universal Morphological Analysis using Structured Nearest Neighbor Prediction
Young-Bum Kim, João Graça, Benjamin Snyder
EMNLP2
2011 Discriminative Phrase-based Lexicalized Reordering Models using Weighted Reordering Graphs
Wang Ling, João Graça, David Martins de Matos, Isabel Trancoso, Alan W. Black
IJCNLP2
2011 Controlling Complexity in Part-of-Speech Induction
abstract
We consider the problem of fully unsupervised learning of grammatical (part-of-speech) categories from unlabeled text. The standard maximum-likelihood hidden Markov model for this task performs poorly, because of its weak inductive bias and large model capacity. We address this problem by refining the model and modifying the learning objective to control its capacity via para- metric and non-parametric constraints. Our approach enforces word-category association sparsity, adds morphological and orthographic features, and eliminates hard-to-estimate parameters for rare words. We develop an efficient learning algorithm that is not much more computationally intensive than standard training. We also provide an open-source implementation of the algorithm. Our experiments on five diverse languages (Bulgarian, Danish, English, Portuguese, Spanish) achieve significant improvements compared with previous methods for the same task.
João Graça, Kuzman Ganchev, Luísa Coheur, Fernando Pereira 0003, Ben Taskar
J. Artif. Intell. Res.1
2011 Posterior Sparsity in Unsupervised Dependency Parsing
Jennifer Gillenwater, Kuzman Ganchev, João Graça, Fernando Pereira 0003, Ben Taskar
J. Mach. Learn. Res.3
2010 Developing a Deep Linguistic Databank Supporting a Collection of Treebanks: the CINTIL DeepGramBank
António Branco, Francisco Costa, João Silva 0004, Sara Silveira, Sérgio Castro, Mariana Avelãs, Clara Pinto, João Graça
LREC8
2010 Learning Tractable Word Alignment Models with Complex Constraints
abstract
Word-level alignment of bilingual text is a critical resource for a growing variety of tasks. Probabilistic models for word alignment present a fundamental trade-off between richness of captured constraints and correlations versus efficiency and tractability of inference. In this article, we use the Posterior Regularization framework (Graça, Ganchev, and Taskar 2007) to incorporate complex constraints into probabilistic models during learning without changing the efficiency of the underlying model. We focus on the simple and tractable hidden Markov model, and present an efficient learning algorithm for incorporating approximate bijectivity and symmetry constraints. Models estimated with these constraints produce a significant boost in performance as measured by both precision and recall of manually annotated alignments for six language pairs. We also report experiments on two different tasks where word alignments are required: phrase-based machine translation and syntax transfer, and show promising improvements over standard methods.
João Graça, Kuzman Ganchev, Ben Taskar
Comput. Linguistics1
2010 Posterior Regularization for Structured Latent Variable Models
Kuzman Ganchev, João Graça, Jennifer Gillenwater, Ben Taskar
J. Mach. Learn. Res.2
2009 Posterior vs Parameter Sparsity in Latent Variable Models
abstract
In this paper we explore the problem of biasing unsupervised models to favor sparsity. We extend the posterior regularization framework [8] to encourage the model to achieve posterior sparsity on the unlabeled training data. We apply this new method to learn first-order HMMs for unsupervised part-of-speech (POS) tagging, and show that HMMs learned this way consistently and significantly out-performs both EM-trained HMMs, and HMMs with a sparsity-inducing Dirichlet prior trained by variational EM. We evaluate these HMMs on three languages — English, Bulgarian and Portuguese — under four conditions. We find that our method always improves performance with respect to both baselines, while variational Bayes actually degrades performance in most cases. We increase accuracy with respect to EM by 2.5%-8.7% absolute and we see improvements even in a semisupervised condition where a limited dictionary is provided.
João Graça, Kuzman Ganchev, Ben Taskar, Fernando Pereira 0003
NIPS1
2008 Better Alignments = Better Translations?
Kuzman Ganchev, João Graça, Ben Taskar
ACL2
2008 Building a Golden Collection of Parallel Multi-Language Word Alignment
João Graça, Joana Paulo Pardal, Luísa Coheur, Diamantino Caseiro
LREC1
2008 Multi-View Learning over Structured and Non-Identical Outputs
Kuzman Ganchev, João Graça, John Blitzer, Ben Taskar
UAI2
2008 Multi-View Learning over Structured and Non-Identical Outputs
Kuzman Ganchev, João Graça, John Blitzer, Ben Taskar
UAI2
2007 Frustratingly Hard Domain Adaptation for Dependency Parsing
Mark Dredze, John Blitzer, Partha P. Talukdar, Kuzman Ganchev, João Graça, Fernando Pereira 0003
EMNLP-CoNLL5
2007 Expectation Maximization and Posterior Constraints
abstract
The expectation maximization (EM) algorithm is a widely used maximum likelihood estimation procedure for statistical models when the values of some of the variables in the model are not observed. Very often, however, our aim is primarily to find a model that assigns values to the latent variables that have intended meaning for our data and maximizing expected likelihood only sometimes accomplishes this. Unfortunately, it is typically difficult to add even simple a-priori information about latent variables in graphical models without making the models overly complex or intractable. In this paper, we present an efficient, principled way to inject rich constraints on the posteriors of latent variables into the EM algorithm. Our method can be used to learn tractable graphical models that satisfy additional, otherwise intractable constraints. Focusing on clustering and the alignment problem for statistical machine translation, we show that simple, intuitive posterior constraints can greatly improve the performance over standard baselines and be competitive with more complex, intractable models.
João Graça, Kuzman Ganchev, Ben Taskar
NIPS1