Artificial intelligence has a long history of learning from domain problems ranging from chess to jeopardy. In this work, we look at a problem stemming from social science, namely, how do social relationships influence communication content and vice versa. The tools used to study communication content (content analysis) have rarely been combined with those used to study social relationships (social network analysis). Furthermore, there is even less work addressing the longitudinal characteristics of such a combination. This paper presents a general framework for measuring the dynamic bi-directional influence between communication content and social networks. The framework leverages the idea that knowledge about both kinds of networks can be represented using the same knowledge representation. In particular, through the use of Semantic Web standards, the extraction of networks is made easier. The framework is applied to two use-cases: online forum discussions and conference publications. The results provide a new perspective over the dynamics involving both social networks and communication content.

Today, mobile robots are increasingly expected to operate in ever more complex and dynamic environments.In order to carry out many of the higher level tasks envisioned a semantic understanding of a workspace is pivotal. Here our field has benefited significantly from successes in machine learning and vision: applications in robotics of off-the-shelf object detectors are plentiful. This paper outlines an online, any-time planning framework enabling the active exploration of such detections. Our approach exploits the ability to move to different vantage points and implicitly weighs the benefits of gaining more certainty about the existence of an object against the physical cost of the exploration required. The result is a robot which plans trajectories specifically to decrease the entropy of putative detections. Our system is demonstrated to significantly improve detection performance and trajectory length in simulated and real robot experiments.

This paper concerns the creation of an efficient, continuous, non-parametric representation of surfaces implicit in 3D laser data as typically recorded by mobile robots. Our approach explicitly leverages the probabilistic nature of Gaussian Process regression to provide for a principled, adaptive subsampling which automatically prunes redundant data. The algorithm places no restriction on the complexity of the underlying surfaces and enables predictions at arbitrary locations and densities. We present results using real and synthetic data and show that our approach attains decimation factors in excess of two orders of magnitude without significant degradation in fidelity of the workspace reconstructions.

Some of the most successful machine learning algorithms, such as Support Vector Machines, are based on learning linear and kernel predictors with respect to a convex loss function, such as the hinge loss. For classification purposes, a more natural loss function is the 0-1 loss. However, using it leads to a non-convex problem for which there is no known efficient algorithm. In this paper, we describe and analyze a new algorithm for learning linear or kernel predictors with respect to the 0-1 loss function. The algorithm is parameterized by $L$, which quantifies the effective width around the decision boundary in which the predictor may be uncertain. We show that without any distributional assumptions, and for any fixed $L$, the algorithm runs in polynomial time, and learns a classifier which is worse than the optimal such classifier by at most $\epsilon$. We also prove a hardness result, showing that under a certain cryptographic assumption, no algorithm can learn such classifiers in time polynomial in $L$.

The process of extracting useful knowledge from large datasets has become one of the most pressing problems in today’s society. The problem spans entire sectors, from scientists to intelligence analysts and web users, all of whom are constantly struggling to keep up with the larger and larger amounts of content published every day. With this much data, it is often easy to miss the big picture. In this paper, we investigate methods for automatically connecting the dots – providing a structured, easy way to navigate within a new topic and discover hidden connections. We focus on the news domain: given two news articles, our system automatically finds a coherent chain linking them together. For example, it can recover the chain of events leading from the decline of home prices (2007) to the health-care debate (2009). We formalize the characteristics of a good chain and provide efficient algorithms to connect two fixed endpoints. We incorporate user feedback into our framework, allowing the stories to be refined and personalized. Finally, we evaluate our algorithm over real news data. Our user studies demonstrate the algorithm's effectiveness in helping users understanding the news.

Most of the existing personalization systems such as content recommenders or targeted ads focus on individual users and ignore the social situation in which the services are consumed. However, many human activities are social and involve several in-dividuals whose tastes and expectations must be taken into account by the system. When a group profile is not available, different profile aggrega-tion strategies can be applied to recommend ade-quate items to a group of users based on their indi-vidual profiles. We consider an approach intended to determine the factors that influence the choice of an aggregation strategy. We present evaluations made on a large-scale dataset of TV viewings, where real group interests are compared to the pre-dictions obtained by combining individual user profiles according to different strategies.

There are common intuitions about how social graphs are generated (for example, it is common to talk informally about nearby nodes sharing a link). There are also common heuristics for predicting whether two currently unlinked nodes in a graph should be linked (e.g. for suggesting friends in an online social network or movies to customers in a recommendation network). This paper provides what we believe to be the first formal connection between these intuitions and these heuristics. We look at a familiar class of graph generation models in which nodes are associated with locations in a latent metric space and connections are more likely between closer nodes. We also look at popular linkprediction heuristics such as number-of-commonneighbors and its weighted variants [Adamic and Adar, 2003] which have proved successful in predicting missing links, but are not direct derivatives of latent space graph models. We provide theoretical justifications for the success of some measures as compared to others, as reported in previous empirical studies. In particular we present a sequence of formal results that show bounds related to the role that a node’s degree plays in its usefulness for link prediction, the relative importance of short paths versus long paths, and the effects of increasing non-determinism in the link generation process on link prediction quality. Our results can be generalized to any model as long as the latent space assumption holds.

In AI, this area Ontologies that evolve through use to support new has been studied under a variety of names such as forgetting domain tasks can grow extremely large. Moreover, and variable elimination [Eiter et al., 2006; Wang et al., large ontologies require more resources to use and 2008]. We provide a general approach for ranking knowledge have slower response times than small ones. To according to its use and cost, which can be applied to systems help address this problem, we present an online semantic that are limited by memory resources to evaluate memory forgetting algorithm that removes ontology allocation. We also provide a specific approach to select fragments containing infrequently used or cheap to which concepts to remove from an ontology, using the ranking.

In their groundbreaking paper, Bartholdi, Tovey and Trick [1989] argued that many well-known voting rules, such as Plurality, Borda, Copeland and Maximin are easy to manipulate. An important assumption made in that paper is that the manipulator’s goal is to ensure that his preferred candidate is among the candidates with the maximum score, or, equivalently, that ties are broken in favor of the manipulator’s preferred candidate. In this paper, we examine the role of this assumption in the easiness results of [Bartholdi et al., 1989]. We observe that the algorithm presented in [Bartholdi et al., 1989] extends to all rules that break ties according to a fixed ordering over the candidates. We then show that all scoring rules are easy to manipulate if the winner is selected from all tied candidates uniformly at random. This result extends to Maximin under an additional assumption on the manipulator’s utility function that is inspired by the original model of [Bartholdi et al., 1989]. In contrast, we show that manipulation becomes hard when arbitrary polynomial-time tie-breaking rules are allowed, both for the rules considered in [Bartholdi et al., 1989], and for a large class of scoring rules.

Semi-supervised learning algorithms commonly incorporate the available background knowledge such that an expression of the derived model's quality is improved. Depending on the specific context quality can take several forms and can be related to the generalization performance or to a simple clustering coherence measure. Recently, a novel perspective of semi-supervised learning has been put forward, that associates semi-supervised clustering with the efficiency of spectral methods. More precisely, it has been demonstrated that the appropriate use of partial supervision can bias the data Laplacian matrix such that the necessary eigenvector computations are provably accelerated. This result allows data mining practitioners to use background knowledge not only for improving the quality of clustering results, but also for accelerating the required computations. In this paper we initially provide a high level overview of the relevant efficiency maximizing semi-supervised methods such that their theoretical intuitions are comprehensively outlined. Consecutively, we demonstrate how these methods can be extended to handle multiple clusters and also discuss possible issues that may arise in the continuous semi-supervised solution. Finally, we illustrate the proposed extensions empirically in the context of text clustering.