Understanding trust, influence and reputation and constructing computational models of these notions are two essential scientific challenges in computer science as well as social sciences. Although scientists in both disciplines have independently conducted research on these topics over the last couple of decades, there is a huge gap between two literatures. This paper therefore illustrates an interdisciplinary work-in-progress on trust, influence and reputation modeling based on human reasoning. Using a survey-based data collection approach, we would like to understand how humans gain/lose trust in their daily life interactions and how behavior/attitudes of humans can be influenced or shaped in various social encounters. The data will be then transformed into mathematical models to be used in technological or software systems.

Recommender systems provide personalized item suggestions by identifying patterns in past user-item preferences. Most existing approaches for recommender systems work on a single domain, i.e., use user preferences from one domain and recommend items from the same domain. Recently, some recommendation models have been proposed to use user preferences from multiple related item source domains to improve recommendation accuracy for a target item domain, an area of research known as cross-domain recommender systems. One typical assumption in these systems is that users, items, and user preferences for items are similar across domains. In this paper, we introduce a new cross-domain recommendation problem which does not meet this typical assumption. For example, for some scientometric datasets, when the objective is to recommend co-authors, conferences, and references, respectively, to authors, although the users are similar across domains, the items and user-item preferences are different. To address this problem, we propose two approaches to aggregate knowledge from multiple domains. Our approaches allow us to control the knowledge transferred between domains. Experimental results on a DBLP subset show that the proposed cross-domain approaches are helpful in improving recommendation accuracy as compared to single domain approaches.

Saving energy is a major concern. Hence, it is fundamental to design and construct buildings that are energy-efficient. It is known that the early stage of architectural design has a significant impact on this matter. However, it is complex to create designs that are optimally energy efficient, and at the same time balance other essential criterias such as economics, space, and safety. One state-of-the art approach is to create parametric designs, and use a genetic algorithm to optimize across different objectives. We further improve this method, by aggregating the solutions of multiple agents. We evaluate diverse teams, composed by different agents; and uniform teams, composed by multiple copies of a single agent. We test our approach across three design cases of increasing complexity, and show that the diverse team provides a significantly larger percentage of optimal solutions than single agents.

We motivate and develop an additive autoregressive hidden Markov model specifically designed to work on the task of energy disaggregation; that is, separating a whole-building electricity signal into its component device signals whose sum is the aggregate signal observed by a smart meter. This model assumes each device in the building operates as an individual autoregressive HMM, where hidden states represent the underlying power mode of the device and Gaussian emissions correspond to that device's power consumption. The additive property models the observed output (whole-building power signal) as the sum of the emissions of multiple hidden states (i.e., as the sum of individual consumptions of multiple devices in the building). The autoregressive property realistically models how many appliances consume energy and is a new extension to previous work using factorial HMMs for energy disaggregation. Finally, our model also includes a robust mixture component, via an L1-regularized noise term, that can absorb outliers arising in this setting from unknown or rarely-used devices. We extract the power signals and underlying state sequences of single devices in a stagewise fashion and illustrate the results of this process on the Reference Energy Disaggregation Dataset (REDD).

Stochastic Physical Search (SPS) refers to the search for an item in a physical environment where the item's price is stochastic, and where the cost to obtain the item includes both travel and purchase costs. This type of problem models task planning scenarios where the cost of completing an objective at a location is drawn from a probability distribution, reflecting the influence of unknown factors. Prior work on this domain has focused on solutions where the expected cost is minimized. Recently, SPS problems with other objectives have been proposed and theoretically analyzed, in particular when either the budget or the desired probability of success is fixed. However, general optimal solvers for these new variants do not yet exist. We present algorithms for optimal solution of these variants on general graphs. We formulate them as mixed integer linear programming problems, and solve them using an off-the-shelf MILP solver. We then develop custom branch and bound algorithms which result in a dramatic reduction in computation speed. Using these algorithms, we generate empirical insights into the hardness landscape of the fixed budget and fixed probability of success SPS variants.

We built a conversational agent performing social promotion (CASP) to assist in automation of interacting with Facebook friends. CASP relies on a domain-independent natural language relevance technique which filters web mining results to support a conversation with friends and other network members. In this study we focus on recognizing friends’ intents to better support automated conversation with them. We learn the plausible sequences of communicative actions and mental states as they are expressed in text to support plausible dialogue. We evaluate the relevance of the constructed conversations with respect to suitability of topicality and communicative actions, measuring how human users loose trust in the system. It is confirmed that maintaining a plausible sequences of communicative actions in automated postings is important for retaining trust of human peers and efficient social promotion by means of CASP.

This paper is concerned with extension of AngledCORE-9 by Sokeh, Gould, and Renz, a comprehensive representation of spatial information that can be efficiently extracted from interacting objects present in video using their approximated bounding box. Spatial information is important for identification of relation between multiple objects, hence the work is a step forward for tasks such as semantics content analysis and visual information access. To that end we present an approach to incorporating the spatiotemporal volume of objects into AngledCORE-9. The approach is able to detect, track and segment object volumes from a video stream, based on which spatial information is identified in an efficient manner. Accurate spatial and temporal information can be obtained by precise representation of the shape region and the oriented bounding box. A human action classification task is adopted in order to assess the performance of the approach. The experiment with two challenging datasets indicates that the outcome of this approach is comparable to the state-of-the-art.

Reinforcement learning with reward shaping is a well established but often computationally expensive approach to large multiagent systems. Agent partitioning can reduce this computational complexity by treating each partition of agents as an independent problem. We introduce a novel agent partitioning approach called Reward/Utility-Based Impact (RUBI). RUBI finds an effective partitioning of agents while requiring no prior domain knowledge, improves performance by discovering a non-trivial agent partitioning, and leads to faster simulations. We test RUBI in the Air Traffic Flow Management Problem (ATFMP), where there are tens of thousands of aircraft affecting the system and no obvious similarity metric between agents. When partitioning with RUBI in the ATFMP, there is a 37% increase in performance, with a 510x speed increase over non-partitioning approaches. Additionally, RUBI matches the performance of the current domain-dependent ATFMP gold standard using no prior knowledge and with 10% faster performance.

While most work on trajectory mining is applied to pre- dict movements of mobile users, in this paper we consider a more general problem of building behavior models of users from their state-action trajectories. We assume that the user behavior can be compactly modeled as a Probabilistic State-Dependent Grammar (PSDG) which represents a hierarchical policy. The key problem is that while the states and actions of the user are directly observed, his intentional structure is not. We propose to learn the user’s policy from a set of selected trajectories and intention queries at selected states in the trajectory. Our main contributions are an algorithm for learning hierarchical policies from state-action trajectories, and principled heuristics for selecting suitable trajectories and intention queries. Experiments in multiple domains show that our approach is effective and more sample-efficient than learning non-hierarchical policies.

In Reinforcement Learning, it is common to use optimistic initialization of value functions to encourage exploration. However, such an approach generally depends on the domain, viz., the scale of the rewards must be known, and, when using function approximation, the feature representation must have a constant norm. We present a simple approach that performs optimistic initialization with less dependence on the domain.