Genre
Accuracy of Latent-Variable Estimation in Bayesian Semi-Supervised Learning
Hierarchical probabilistic models, such as Gaussian mixture models, are widely used for unsupervised learning tasks. These models consist of observable and latent variables, which represent the observable data and the underlying data-generation process, respectively. Unsupervised learning tasks, such as cluster analysis, are regarded as estimations of latent variables based on the observable ones. The estimation of latent variables in semi-supervised learning, where some labels are observed, will be more precise than that in unsupervised, and one of the concerns is to clarify the effect of the labeled data. However, there has not been sufficient theoretical analysis of the accuracy of the estimation of latent variables. In a previous study, a distribution-based error function was formulated, and its asymptotic form was calculated for unsupervised learning with generative models. It has been shown that, for the estimation of latent variables, the Bayes method is more accurate than the maximum-likelihood method. The present paper reveals the asymptotic forms of the error function in Bayesian semi-supervised learning for both discriminative and generative models. The results show that the generative model, which uses all of the given data, performs better when the model is well specified.
Distributed Online Learning via Cooperative Contextual Bandits
Tekin, Cem, van der Schaar, Mihaela
In this paper we propose a novel framework for decentralized, online learning by many learners. At each moment of time, an instance characterized by a certain context may arrive to each learner; based on the context, the learner can select one of its own actions (which gives a reward and provides information) or request assistance from another learner. In the latter case, the requester pays a cost and receives the reward but the provider learns the information. In our framework, learners are modeled as cooperative contextual bandits. Each learner seeks to maximize the expected reward from its arrivals, which involves trading off the reward received from its own actions, the information learned from its own actions, the reward received from the actions requested of others and the cost paid for these actions - taking into account what it has learned about the value of assistance from each other learner. We develop distributed online learning algorithms and provide analytic bounds to compare the efficiency of these with algorithms with the complete knowledge (oracle) benchmark (in which the expected reward of every action in every context is known by every learner). Our estimates show that regret - the loss incurred by the algorithm - is sublinear in time. Our theoretical framework can be used in many practical applications including Big Data mining, event detection in surveillance sensor networks and distributed online recommendation systems.
Deep metric learning using Triplet network
Deep learning has proven itself as a successful set of models for learning useful semantic representations of data. These, however, are mostly implicitly learned as part of a classification task. In this paper we propose the triplet network model, which aims to learn useful representations by distance comparisons. A similar model was defined by Wang et al. (2014), tailor made for learning a ranking for image information retrieval. Here we demonstrate using various datasets that our model learns a better representation than that of its immediate competitor, the Siamese network. We also discuss future possible usage as a framework for unsupervised learning.
Reports of the Workshops Held at the Tenth AAAI Conference on Artificial Intelligence and Interactive Digital Entertainment
Barnes, Tiffany (North Carolina State University) | Bown, Oliver (University of Sydney) | Buro, Michael (University of Alberta) | Cook, Michael (Goldsmiths College, University of London) | Eigenfeldt, Arne (Simon Fraser University) | Muรฑoz-Avila, Hรฉctor (Lehigh University) | Ontaรฑรณn, Santiago (Drexel University) | Pasquier, Philippe (Simon Fraser University) | Tomuro, Noriko (DePaul University) | Young, R. Michael (North Carolina State University) | Zook, Alexander (Georgia Institute of Technology)
The AIIDE-14 Workshop program was held Friday and Saturday, October 3โ4, 2014 at North Carolina State University in Raleigh, North Carolina. The workshop program included five workshops covering a wide range of topics. The titles of the workshops held Friday were Games and Natural Language Processing, and Artificial Intelligence in Adversarial Real-Time Games. The titles of the workshops held Saturday were Diversity in Games Research, Experimental Artificial Intelligence in Games, and Musical Metacreation. This article presents short summaries of those events.
Reports of the AAAI 2014 Conference Workshops
Albrecht, Stefano V. (University of Edinburgh) | Barreto, Andrรฉ M. S. (Brazilian National Laboratory for Scientific Computing) | Braziunas, Darius (Kobo Inc.) | Buckeridge, David L. (McGill University) | Cuayรกhuitl, Heriberto (Heriot-Watt University) | Dethlefs, Nina (Heriot-Watt University) | Endres, Markus (University of Augsburg) | Farahmand, Amir-massoud (Carnegie Mellon University) | Fox, Mark (University of Toronto) | Frommberger, Lutz (University of Bremen) | Ganzfried, Sam (Carnegie Mellon University) | Gil, Yolanda (University of Southern California) | Guillet, Sรฉbastien (Universitรฉ du Quรฉbec ร Chicoutimi) | Hunter, Lawrence E. (University of Colorado School of Medicine) | Jhala, Arnav (University of California Santa Cruz) | Kersting, Kristian (Technical University of Dortmund) | Konidaris, George (Massachusetts Institute of Technology) | Lecue, Freddy (IBM Research) | McIlraith, Sheila (University of Toronto) | Natarajan, Sriraam (Indiana University) | Noorian, Zeinab (University of Saskatchewan) | Poole, David (University of British Columbia) | Ronfard, Rรฉmi (University of Grenoble) | Saffiotti, Alessandro (Orebro University) | Shaban-Nejad, Arash (McGill University) | Srivastava, Biplav (IBM Research) | Tesauro, Gerald (IBM Research) | Uceda-Sosa, Rosario (IBM Research) | Broeck, Guy Van den (Katholieke Universiteit Leuven) | Otterlo, Martijn van (Radboud University Nijmegen) | Wallace, Byron C. (University of Texas) | Weng, Paul (Pierre and Marie Curie University) | Wiens, Jenna (University of Michigan) | Zhang, Jie (Nanyang Technological University)
The AAAI-14 Workshop program was held Sunday and Monday, July 27โ28, 2012, at the Quรฉbec City Convention Centre in Quรฉbec, Canada. Canada. The AAAI-14 workshop program included fifteen workshops covering a wide range of topics in artificial intelligence. The titles of the workshops were AI and Robotics; Artificial Intelligence Applied to Assistive Technologies and Smart Environments; Cognitive Computing for Augmented Human Intelligence; Computer Poker and Imperfect Information; Discovery Informatics; Incentives and Trust in Electronic Communities; Intelligent Cinematography and Editing; Machine Learning for Interactive Systems: Bridging the Gap between Perception, Action and Communication; Modern Artificial Intelligence for Health Analytics; Multiagent Interaction without Prior Coordination; Multidisciplinary Workshop on Advances in Preference Handling; Semantic Cities โ Beyond Open Data to Models, Standards and Reasoning; Sequential Decision Making with Big Data; Statistical Relational AI; and The World Wide Web and Public Health Intelligence. This article presents short summaries of those events.
AAAI Conferences Calendar
This page includes forthcoming AAAI sponsored conferences, conferences presented by AAAI Affiliates, and conferences held in cooperation with AAAI. AI Magazine also maintains a calendar listing that includes nonaffiliated conferences at www.aaai.org/Magazine/calendar.php. Spring Symposium Series will be held AI Research Society Conference. FLAIRS-15 will be held May 18-20, Smart Graphics Conference. Graphics 2015 will be held August 26-sss15.php
Using Semantics and Statistics to Turn Data into Knowledge
Pujara, Jay (University of Maryland, College Park) | Miao, Hui (University of California, Santa Cruz) | Getoor, Lise (Carnegie Mellon University) | Cohen, William W.
Many information extraction and knowledge base construction systems are addressing the challenge of deriving knowledge from text. A key problem in constructing these knowledge bases from sources like the web is overcoming the erroneous and incomplete information found in millions of candidate extractions. To solve this problem, we turn to semantics โ using ontological constraints between candidate facts to eliminate errors. In this article, we represent the desired knowledge base as a knowledge graph and introduce the problem of knowledge graph identification, collectively resolving the entities, labels, and relations present in the knowledge graph. Knowledge graph identification requires reasoning jointly over millions of extractions simultaneously, posing a scalability challenge to many approaches. We use probabilistic soft logic (PSL), a recently-introduced statistical relational learning framework, to implement an efficient solution to knowledge graph identification and present state-of-the-art results for knowledge graph construction while performing an order of magnitude faster than competing methods.
Entity Type Recognition for Heterogeneous Semantic Graphs
Sleeman, Jennifer (University of Maryland Baltimore County.) | Finin, Tim (University of Maryland Baltimore County.) | Joshi, Anupam (University of Maryland Baltimore County.)
We describe an approach for identifying fine-grained entity types in heterogeneous data graphs that is effective for unstructured data or when the underlying ontologies or semantic schemas are unknown. Identifying fine-grained entity types, rather than a few high-level types, supports coreference resolution in heterogeneous graphs by reducing the number of possible coreference relations that must be considered. Big data problems that involve integrating data from multiple sources can benefit from our approach when the datas ontologies are unknown, inaccessible or semantically trivial. For such cases, we use supervised machine learning to map entity attributes and relations to a known set of attributes and relations from appropriate background knowledge bases to predict instance entity types. We evaluated this approach in experiments on data from DBpedia, Freebase, and Arnetminer using DBpedia as the background knowledge base.
Early Steps Towards Web Scale Information Extraction with LODIE
Gentile, Anna Lisa (The University of Sheffield) | Zhang, Ziqi (The University of Sheffield) | Ciravegna, Fabio (The University of Sheffield)
Information extraction (IE) is the technique for transforming unstructured textual data into structured representation that can be understood by machines. The exponential growth of the Web generates an exceptional quantity of data for which automatic knowledge capture is essential. This work describes the methodology for web scale information extraction in the LODIE project (linked open data information extraction) and highlights results from the early experiments carried out in the initial phase of the project. LODIE aims to develop information extraction techniques able to scale at web level and adapt to user information needs. The core idea behind LODIE is the usage of linked open data, a very large-scale information resource, as a ground-breaking solution for IE, which provides invaluable annotated data on a growing number of domains. This article has two objectives. First, describing the LODIE project as a whole and depicting its general challenges and directions. Second, describing some initial steps taken towards the general solution, focusing on a specific IE subtask, wrapper induction.