Africa
Minimal Narrative Annotation Schemes and Their Applications
Rahimtoroghi, Elahe (University of California, Santa Cruz) | Corcoran, Thomas (University of California, Santa Cruz) | Swanson, Reid (University of California, Santa Cruz) | Walker, Marilyn A. (University of California, Santa Cruz) | Sagae, Kenji (Institute for Creative Technologies, University of Southern California) | Gordon, Andrew (Institute for Creative Technologies, University of Southern California)
The increased use of large corpora in narrative research has created new opportunities for empirical research and intelligent narrative technologies. To best exploit the value of these corpora, several research groups are eschewing complex discourse analysis techniques in favor of high-level minimalist narrative annotation schemes that can be quickly applied, achieve high inter-rater agreement, and are amenable to automation using machine-learning techniques. In this paper we compare different annotation schemes that have been employed by two groups of researchers to annotate large corpora of narrative text. Using a dual-annotation methodology, we investigate the correlation between narrative clauses distinguished by their structural role (orientation, action, evaluation), their subjectivity, and their narrative level within the discourse. We find that each simple narrative annotation scheme captures a structurally distinct characteristic of real-world narratives, and each combination of labels is evident in a corpus of 19 weblog narratives (951 narrative clauses). We discuss several potential applications of minimalist narrative annotation schemes, noting the combination of label across these two annotation schemes that best support each task.
Behavioural Domain Knowledge Transfer for Autonomous Agents
Rosman, Benjamin Saul (The Council for Scientific and Industrial Research)
An agent continuously performing different tasks in the same domain has the opportunity to learn, over the course of its operational lifetime, about the behavioural regularities afforded by the domain. This paper addresses the problem of learning a task independent behaviour model based on the underlying structure of a domain which is common across multiple tasks presented to an autonomous agent. Our approach involves learning action priors: a behavioural model which encodes a notion of local common sense behaviours in the domain, conditioned on either the state or observations of the agent. This knowledge is accumulated and transferred as an exploration behaviour whenever a new task is presented to the agent. The effect is that as the agent encounters more tasks, it is able to learn them faster and achieve greater overall performance. This approach is illustrated in experiments in a simulated extended navigation domain.
Building Blocks of Social Intelligence: Enabling Autonomy for Socially Intelligent and Assistive Robots
Mead, Ross Alan (University of Southern California) | Atrash, Amin (University of Southern California) | Kaszubski, Edward (University of Southern California) | Clair, Aaron St. (University of Southern California) | Greczek, Jillian (University of Southern California) | Clabaugh, Caitlyn (University of Southern California) | Kohan, Brian (University of Southern California) | Mataric, Maja J. (University of Southern California)
Vocalics is the study of the nonverbal aspects of speech, such as volume, pitch, and rate. Our contribution is a parametric We present an overview of the control, recognition, decision-making, vocalic behavior controller that autonomously adjusts and learning techniques utilized by the Interaction the robot speaker volume based on models of how a Lab (robotics.usc.edu/interaction) at the University human user will hear speech produced by the robot. These of Southern California (USC) to enable autonomy in sociable models vary with distance, orientation, and perceived environmental and socially assistive robots. These techniques are implemented interference (Mead & Matarić 2014). Our future with two software libraries: 1) the Social Behavior work will investigate adapting the pitch and rate of speech Library (SBL) provides autonomous social behavior produced by a robot to improve user speech perception.
Push and Rotate: a Complete Multi-agent Pathfinding Algorithm
Wilde, B. de, ter Mors, A. W., Witteveen, C.
Multi-agent Pathfinding is a relevant problem in a wide range of domains, for example in robotics and video games research. Formally, the problem considers a graph consisting of vertices and edges, and a set of agents occupying vertices. An agent can only move to an unoccupied, neighbouring vertex, and the problem of finding the minimal sequence of moves to transfer each agent from its start location to its destination is an NP-hard problem. We present Push and Rotate, a new algorithm that is complete for Multi-agent Pathfinding problems in which there are at least two empty vertices. Push and Rotate first divides the graph into subgraphs within which it is possible for agents to reach any position of the subgraph, and then uses the simple push, swap, and rotate operations to find a solution; a post-processing algorithm is also presented that eliminates redundant moves. Push and Rotate can be seen as extending Luna and Bekris's Push and Swap algorithm, which we showed to be incomplete in a previous publication. In our experiments we compare our approach with the Push and Swap, MAPP, and Bibox algorithms. The latter algorithm is restricted to a smaller class of instances as it requires biconnected graphs, but can nevertheless be considered state of the art due to its strong performance. Our experiments show that Push and Swap suffers from incompleteness, MAPP is generally not competitive with Push and Rotate, and Bibox is better than Push and Rotate on randomly generated biconnected instances, while Push and Rotate performs better on grids.
The Role of Emotions in Propagating Brands in Social Networks
Hochreiter, Ronald, Waldhauser, Christoph
A key aspect of word of mouth marketing are emotions. Emotions in texts help propagating messages in conventional advertising. In word of mouth scenarios, emotions help to engage consumers and incite to propagate the message further. While the function of emotions in offline marketing in general and word of mouth marketing in particular is rather well understood, online marketing can only offer a limited view on the function of emotions. In this contribution we seek to close this gap. We therefore investigate how emotions function in social media. To do so, we collected more than 30,000 brand marketing messages from the Google+ social networking site. Using state of the art computational linguistics classifiers, we compute the sentiment of these messages. Starting out with Poisson regression-based baseline models, we seek to replicate earlier findings using this large data set. We extend upon earlier research by computing multi-level mixed effects models that compare the function of emotions across different industries. We find that while the well known notion of activating emotions propagating messages holds in general for our data as well. But there are significant differences between the observed industries.
Mixed-Variate Restricted Boltzmann Machines
Tran, Truyen, Phung, Dinh, Venkatesh, Svetha
Restricted Boltzmann Machines (RBM) [9, 5] have recently attracted an increasing attention for their rich capacity in a variety of learning tasks, including multivariate distribution modelling, feature extraction, classification, and construction of deep architectures [8, 19]. An RBM is a two-layer Markov random field in which the visible layer represents observed variables and the hidden layer represents latent aspects of the data. Pairwise interactions are only permitted for units between layers. As a result, the posterior distribution over the hidden variables and the probability of the data generative model are easy to evaluate, allowing fast feature extraction and efficient sampling-based inference [7]. Nonetheless, most existing work in RBMs implicitly assumes that the visible layer contains variables of the same modality. By far the most popular input types are binary [5] and Gaussian [8]. Recent extension includes categorical [21], ordinal [25], Poisson [6] and Beta [13] data. To the best of our knowledge, none has been considered for multicategorical and category-ranking data, nor for a mixed combination of these data types. In this paper, we investigate a generalisation of the RBM for variables of multiple modalities and types.
Thurstonian Boltzmann Machines: Learning from Multiple Inequalities
Tran, Truyen, Phung, Dinh, Venkatesh, Svetha
Restricted Boltzmann machines (RBMs) have proved to be a versatile tool for a wide variety of machine learning tasks and as a building block for deep architectures [12, 24, 28]. The original proposals mainly handle binary visible and hidden units. Whilst binary hidden units are broadly applicable as feature detectors, non-binary visible data requires different designs. Recent extensions to other data types result in type-dependent models: the Gaussian for continuous inputs [12], Beta for bounded continuous inputs [16], Poisson for count data [9], multinomial for unordered categories [25], and ordinal models for ordered categories [37, 35]. The Boltzmann distribution permits several types to be jointly modelled, thus making the RBM a good tool for multimodal and complex social survey analysis. The work of [20, 29, 40] combines continuous (e.g., visual and audio) and discrete modalities (e.g., words). The work of [34] extends the idea further to incorporate ordinal and rank data. However, there are conceptual drawbacks: First, conditioned on the hidden layer, they are still separate type-specific models; second, handling ordered categories and ranks is not natural; and third, specifying direct correlation between these types remains difficult. The main thesis of this paper is that many data types can be captured in one unified model.
A Comparative Study of Meta-heuristic Algorithms for Solving Quadratic Assignment Problem
Said, Gamal Abd El-Nasser A., Mahmoud, Abeer M., El-Horbaty, El-Sayed M.
Optimization problems arise in various disciplines such as engineering design, manufacturing system, economics etc. thus in view of the practical utility of optimization problems there is a need for efficient and robust computational algorithms which can solve optimization problems arising in different fields. Several NPhard combinatorial optimization problems, such as the traveling salesman problem, and yard management of container terminals can be modeled as QAPs.. Optimization is a process that finds a best, or optimal, solution for a problem. An optimization problem is defined as: Finding values of the variables that minimize or maximize the objective function while satisfying the constraints. The Optimization problems are centered on three factors: (1) an objective function which is to be minimized or maximized.
Scalable Sparse Covariance Estimation via Self-Concordance
Kyrillidis, Anastasios (Ecole Polytechnique Fédérale de Lausanne (EPFL)) | Mahabadi, Rabeeh Karimi (Ecole Polytechnique Fédérale de Lausanne (EPFL)) | Dinh, Quoc Tran (Ecole Polytechnique Fédérale de Lausanne (EPFL)) | Cevher, Volkan (Ecole Polytechnique Fédérale de Lausanne (EPFL))
We consider the class of convex minimization problems, composed of a self-concordant function, such as the logdet metric, a convex data fidelity term h(.) and, a regularizing — possibly non-smooth — function g(.). This type of problems have recently attracted a great deal of interest, mainly due to their omnipresence in top-notch applications. Under this locally Lipschitz continuous gradient setting, we analyze the convergence behavior of proximal Newton schemes with the added twist of a probable presence of inexact evaluations. We prove attractive convergence rate guarantees and enhance state-of-the-art optimization schemes to accommodate such developments. Experimental results on sparse covariance estimation show the merits of our algorithm, both in terms of recovery efficiency and complexity.
Adaptive Singleton-Based Consistencies
Balafrej, Amine (University of Montpellier / University Mohammed V Agdal) | Bessiere, Christian (University of Montpellier) | Bouyakhf, El Houssine (University Mohammed V Agdal) | Trombettoni, Gilles (University of Montpellier)
Singleton-based consistencies have been shown to dramatically improve the performance of constraint solvers on some difficult instances. However, they are in general too expensive to be applied exhaustively during the whole search. In this paper, we focus on partition-one-AC, a singleton-based consistency which, as opposed to singleton arc consistency, is able to prune values on all variables when it performs singleton tests on one of them. We propose adaptive variants of partition-one-AC that do not necessarily run until having proved the fixpoint. The pruning can be weaker than the full version but the computational effort can be significantly reduced. Our experiments show that adaptive Partition-one-AC can obtain significant speed-ups over arc consistency and over the full version of partition-one-AC.