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From Frequency to Meaning: Vector Space Models of Semantics

Journal of Artificial Intelligence Research

Computers understand very little of the meaning of human language. This profoundly limits our ability to give instructions to computers, the ability of computers to explain their actions to us, and the ability of computers to analyse and process text. Vector space models (VSMs) of semantics are beginning to address these limits. This paper surveys the use of VSMs for semantic processing of text. We organize the literature on VSMs according to the structure of the matrix in a VSM. There are currently three broad classes of VSMs, based on term-document, word-context, and pair-pattern matrices, yielding three classes of applications. We survey a broad range of applications in these three categories and we take a detailed look at a specific open source project in each category. Our goal in this survey is to show the breadth of applications of VSMs for semantics, to provide a new perspective on VSMs for those who are already familiar with the area, and to provide pointers into the literature for those who are less familiar with the field.


The Fifth International Conference on Intelligent Environments (IE 09): A Report

AI Magazine

The development of intelligent environments is considered an important step toward the realization of the ambient intelligence vision. Greece, served as program chairs. The previous four editions of the IE conference have been held at the University of Essex, UK (in 2005), at the National Technical University of Athens, Greece (in 2006), at the University of Ulm, Germany (in 2007), and at the University of Washington campus in Seattle, Washington, USA (in 2008). The development of intelligent environments is About 120 delegates attended the workshops considered the first and primary step toward the and the conference. These included representatives realization of the ambient intelligence vision.


AutoMed - An Automated Mediator for Multi-Issue Bilateral Negotiations

AAAI Conferences

In this paper, we present AutoMed, an automated mediator for multi-issue bilateral negotiation under time constraints. AutoMed uses a qualitative model to represent the negotiators' preferences. It analyzes the negotiators' preferences, monitors the negotiations and proposes possible solutions for resolving the conflict. We conducted experiments in a simulated environment. The results show that negotiations mediated by AutoMed are concluded significantly faster than non-mediated ones and without any of the negotiators opting out. Furthermore, the subjects in the mediated negotiations are more satisfied from the resolutions than the subjects in the non-mediated negotiations.


Multi-Agent Framework for Modeling of the Formation and Dynamics of Pirate Networks

AAAI Conferences

This paper presents an agent based framework for modeling of the formation and dynamics of pirate networks. The framework consists of (1) development of network formation mechanism and (2) formulation of pirate attack dynamics. Accordingly, the paper attempts to define the characteristics of Pirate Networks and to formulate the rules that govern the operation and evolution of Pirate Networks. We discuss the clan based social system that facilitate pirate formation as well as the pirate network inter-action with the hosting clan system. Using published material, empirical data and surveys the paper attempts to establish credible formation mechanism and operational characterization of pirate attacks. The proposed framework accounts for clan dynamics and the interplay of social, ecological and physical spaces. Finally we conclude with a discussion on exploratory modeling for the refinement of the proposed framework and for empirically grounding proposed simulations.


Clustering by compression

arXiv.org Artificial Intelligence

We present a new method for clustering based on compression. The method doesn't use subject-specific features or background knowledge, and works as follows: First, we determine a universal similarity distance, the normalized compression distance or NCD, computed from the lengths of compressed data files (singly and in pairwise concatenation). Second, we apply a hierarchical clustering method. The NCD is universal in that it is not restricted to a specific application area, and works across application area boundaries. A theoretical precursor, the normalized information distance, co-developed by one of the authors, is provably optimal but uses the non-computable notion of Kolmogorov complexity. We propose precise notions of similarity metric, normal compressor, and show that the NCD based on a normal compressor is a similarity metric that approximates universality. To extract a hierarchy of clusters from the distance matrix, we determine a dendrogram (binary tree) by a new quartet method and a fast heuristic to implement it. The method is implemented and available as public software, and is robust under choice of different compressors. To substantiate our claims of universality and robustness, we report evidence of successful application in areas as diverse as genomics, virology, languages, literature, music, handwritten digits, astronomy, and combinations of objects from completely different domains, using statistical, dictionary, and block sorting compressors. In genomics we presented new evidence for major questions in Mammalian evolution, based on whole-mitochondrial genomic analysis: the Eutherian orders and the Marsupionta hypothesis against the Theria hypothesis.


Geocoding multilingual texts: Recognition, disambiguation and visualisation

arXiv.org Artificial Intelligence

We are presenting a method to recognise geographical references in free text. Our tool must work on various languages with a mi ni-mum of language-dependent resources, except a gazetteer. The main difficulty is to disa mbiguate these place names by distinguis hing places from persons and by selecting the mo st likely place out of a list of homographi c place names world-wide. The system uses a number of language-independent clues and he uristics to disambiguate place name homogra phs. The final aim is to index texts with the countries and cities they mention and to automatically visualise this information on geographical maps using various tools.


Multilingual Part-of-Speech Tagging: Two Unsupervised Approaches

Journal of Artificial Intelligence Research

We demonstrate the effectiveness of multilingual learning for unsupervised part-of-speech tagging. The central assumption of our work is that by combining cues from multiple languages, the structure of each becomes more apparent. We consider two ways of applying this intuition to the problem of unsupervised part-of-speech tagging: a model that directly merges tag structures for a pair of languages into a single sequence and a second model which instead incorporates multilingual context using latent variables. Both approaches are formulated as hierarchical Bayesian models, using Markov Chain Monte Carlo sampling techniques for inference. Our results demonstrate that by incorporating multilingual evidence we can achieve impressive performance gains across a range of scenarios. We also found that performance improves steadily as the number of available languages increases.


Cross-lingual Annotation Projection for Semantic Roles

Journal of Artificial Intelligence Research

This article considers the task of automatically inducing role-semantic annotations in the FrameNet paradigm for new languages. We propose a general framework that is based on annotation projection, phrased as a graph optimization problem. It is relatively inexpensive and has the potential to reduce the human effort involved in creating role-semantic resources. Within this framework, we present projection models that exploit lexical and syntactic information. We provide an experimental evaluation on an English-German parallel corpus which demonstrates the feasibility of inducing high-precision German semantic role annotation both for manually and automatically annotated English data.


MiPPS: A Generative Model for Multi-Manifold Clustering

AAAI Conferences

We propose a generative model for high dimensional data consisting of intrinsically low dimensional clusters that are noisily sampled. The proposed model is a mixture of probabilistic principal surfaces (MiPPS) optimized using expectation maximization. We use a Bayesian prior on the model parameters to maximize the corresponding marginal likelihood. We also show empirically that this optimization can be biased towards a good local optimum by using our prior intuition to guide the initialization phase The proposed unsupervised algorithm naturally handles cases where the data lies on multiple connected components of a single manifold and where the component manifolds intersect. In addition to clustering, we learn a functional model for the underlying structure of each component cluster as a parameterized hyper-surface in ambient noise.This model is used to learn a global embedding that we use for visualization of the entire dataset. We demonstrate the performance of MiPPS in separating and visualizing land cover types in a hyperspectral dataset.


A Progression of Cognitive Frameworks

AAAI Conferences

The anthropological and economic history of humanity gives evidence of a progression of cognitive frameworks. There are three cognitive perspectives, in order: living in the present, living in the past, and living in the future. They correspond to three levels of competency with abstract thought: concrete thought only, abstract thought with correlations, and abstract thought with both correlations and causality. This appears to explain the fundamental differences between primitive cultures, traditional cultures, and modern cultures: differences in economics, politics, personality, and anthropological differences in general. So, not only does this theory succinctly explain a wide range of human behavior, but because it does, it appears to be a valid theory and a promising way to decompose abstract thought into its component parts for future cognitive research. These frameworks are discussed along with their implications of exploiting this progression to simplify the problem of developing an AI.