Recommender systems are increasingly used for personalised navigation through large amounts of information, especially in the e-commerce domain for product purchase advice. Whilst much research effort is spent on developing recommenders further, there is little to no effort spent on analysing the impact of them - neither on the supply (company) nor demand (consumer) side. In this paper, we investigate the diversity impact of a movie recommender. We define diversity for different parts of the domain and measure it in different ways. The novelty of our work is the usage of real rating data (from Netflix) and a recommender system for investigating the (hypothetical) effects of various configurations of the system and users' choice models.We consider a number of different scenarios (which differ in the agent's choice model), run very extensive simulations, analyse various measurements regarding experimental validation and diversity, and report on selected findings. The choice models are an essential part of our work, since these can be influenced by the owner of the recommender once deployed.

This paper is concerned with algorithms for prediction of discrete sequences over a finite alphabet, using variable order Markov models. The class of such algorithms is large and in principle includes any lossless compression algorithm. We focus on six prominent prediction algorithms, including Context Tree Weighting (CTW), Prediction by Partial Match (PPM) and Probabilistic Suffix Trees (PSTs). We discuss the properties of these algorithms and compare their performance using real life sequences from three domains: proteins, English text and music pieces. The comparison is made with respect to prediction quality as measured by the average log-loss. We also compare classification algorithms based on these predictors with respect to a number of large protein classification tasks. Our results indicate that a "decomposed" CTW (a variant of the CTW algorithm) and PPM outperform all other algorithms in sequence prediction tasks. Somewhat surprisingly, a different algorithm, which is a modification of the Lempel-Ziv compression algorithm, significantly outperforms all algorithms on the protein classification problems.

We propose a model for errors in sung queries, a variant of the hidden Markov model (HMM). This is a solution to the problem of identifying the degree of similarity between a (typically error-laden) sung query and a potential target in a database of musical works, an important problem in the field of music information retrieval. Similarity metrics are a critical component of query-by-humming (QBH) applications which search audio and multimedia databases for strong matches to oral queries. Our model comprehensively expresses the types of error or variation between target and query: cumulative and non-cumulative local errors, transposition, tempo and tempo changes, insertions, deletions and modulation. The model is not only expressive, but automatically trainable, or able to learn and generalize from query examples. We present results of simulations, designed to assess the discriminatory potential of the model, and tests with real sung queries, to demonstrate relevance to real-world applications.

We present a probabilistic generative model for timing deviations in expressive music performance. The structure of the proposed model is equivalent to a switching state space model. The switch variables correspond to discrete note locations as in a musical score. The continuous hidden variables denote the tempo. We formulate two well known music recognition problems, namely tempo tracking and automatic transcription (rhythm quantization) as filtering and maximum a posteriori (MAP) state estimation tasks. Exact computation of posterior features such as the MAP state is intractable in this model class, so we introduce Monte Carlo methods for integration and optimization. We compare Markov Chain Monte Carlo (MCMC) methods (such as Gibbs sampling, simulated annealing and iterative improvement) and sequential Monte Carlo methods (particle filters). Our simulation results suggest better results with sequential methods. The methods can be applied in both online and batch scenarios such as tempo tracking and transcription and are thus potentially useful in a number of music applications such as adaptive automatic accompaniment, score typesetting and music information retrieval.

This paper presents an implemented system for recognizing the occurrence of events described by simple spatial-motion verbs in short image sequences. The semantics of these verbs is specified with event-logic expressions that describe changes in the state of force-dynamic relations between the participants of the event. An efficient finite representation is introduced for the infinite sets of intervals that occur when describing liquid and semi-liquid events. Additionally, an efficient procedure using this representation is presented for inferring occurrences of compound events, described with event-logic expressions, from occurrences of primitive events. Using force dynamics and event logic to specify the lexical semantics of events allows the system to be more robust than prior systems based on motion profile.

In this study, we analyze two corpora of art critiques: one on the subject of photography and the other on the subject of modern art. We use two computational tools, the Gramulator and GPAT to analyze both sets of texts. The Gramulator was used to show the indicative linguistic features that make photography criticism a distinct genre from modern art criticism. Results suggest that lexical features, structural formats, and genre consistency differed significantly between the two corpora. The findings provide information for teachers, students, publishers, and curriculum developers for creating more effective writing and teaching materials. This includes material for English for Specific Purposes (ESP) in the form of textbooks, workbooks and other external learning material.

With the rapid development of technologies for fast access to the Internet and the popularization of digital cameras, enormous digital images are posted and shared online everyday. Simultaneously, web images are usually organized by topics of events and are often assigned appropriate topic-related text descriptions. Given a set of images along with corresponding texts, a challenging problem is how to utilize the available information to perform image retrieval tasks, such as image classification and image clustering. Previous works on image categorization focus on either adopting text or image features, or simply combining these two types of information together. In this paper, we propose two novel approaches (Dynamic Weighting and Region-based Semantic Concept Integration) to categorize the images under the "supervision" of topic-related text descriptions; In addition, we provide a comparative experimental investigation on utilizing text and image information to tackle image classification. Empirical experiments on a manually collected image dataset (consisting of images related to the events after disasters) demonstrate the efficacy of our proposed classification methods.

Hard news articles, just like op-ed articles, can reflect a media organization's bias. This study assesses bias in the hard news articles published by Fox News and MSNBC. Indicative linguistic features identified by the Gramulator reveal biases in corpora from the two networks.

The New York Public Library is participating in the Chronicling America initiative to develop an online searchable database of historically significant newspaper articles. Microfilm copies of the papers are scanned and high resolution OCR software is run on them. The text from the OCR provides a wealth of data and opinion for researchers and historians. However, the categorization of articles provided by the OCR engine is rudimentary and a large number of the articles are labeled ``editorial" without further categorization. To provide a more refined grouping of articles, unsupervised machine learning algorithms (such as K-Means) are being investigated. The K-Means algorithm requires tuning of parameters such as the number of clusters and mechanism of seeding to ensure that the search is not prone to being caught in a local minima. We designed a pilot study to observe whether humans are adept at finding sub-categories. The subjective labels provided by humans are used as a guide to compare performance of the automated clustering techniques. In addition, seeds provided by annotators are carefully incorporated into a semi-supervised K-Means algorithm (Seeded K-Means); empirical results indicate that this helps to improve performance and provides an intuitive sub-categorization of the articles labeled ``editorial" by the OCR engine.

In recent years, there has been considerable interest in the use of planning techniques in the area of new media. Many traditional planning notions no longer apply in the context of these applications. In particular, it can be difficult to answer the important question of what constitutes a good plan for the domain, but there is an emerging consensus that plan dynamics play an important role. As a consequence, it is important to support representation of such aspects. Our solution is to introduce a meta-level of representation that is an abstraction of the domain with respect to both time and causality, and to develop a visual representation of this in the form of a narrative arc. This visual representation can then be used in a visual programming approach to the exploration and specification of plan dynamics. In the paper we outline this approach to meta-level representation using constraints along with the visual programming interface we have developed. We illustrate the approach with examples of visual programming in the development of an interactive entertainment system based on Shakespeare's play ``The Merchant of Venice''