Overview
Distributed Problem Solving
Yeoh, William (Singapore Management University) | Yokoo, Makoto (Kyushu University)
Distributed problem solving is a subfield within multiagent systems, where agents are assumed to be part of a team and collaborate with each other to reach a common goal. In this article, we illustrate the motivations for distributed problem solving and provide an overview of two distributed problem solving models, namely distributed constraint satisfaction problems (DCSPs) and distributed constraint optimization problems (DCOPs), and some of their algorithms.
Agent-Based Modeling and Simulation
Klรผgl, Franziska (Orebro University) | Bazzan, Ana L. C. (Universidade Federal do Rio Grande do Sul)
This article gives an introduction to agent-based modeling and simulation (ABMS). After a general discussion about modeling and simulation, we address the basic concept of ABMS, focusing on its generative and bottom-up nature, its advantages as well as its pitfalls. The subsequent part of the article deals with application-oriented aspects, including selected tools and well-known applications. In order to illustrate the benefits of using ABMS, we focus on several aspects of a well-known area related to simulation of complex systems, namely traffic. At the end, a brief look into future challenges is given.
A Review of Student Modeling Techniques in Intelligent Tutoring Systems
Harrison, Brent (North Carolina State University) | Roberts, David (North Carolina State)
In this paper, we survey techniques used in intelligent tutoring systems (ITSs) to model student knowledge. The three techniques that we review in detail are knowledge tracing, performance factor analysis, and matrix factorization. We also briefly cover other techniques that have been used. This review is meant to be a repository of knowledge for those who want to integrate these techniques into serious games. It is also meant to increase awareness and interest as to the techniques available that can be integrated into serious games.
Make it So: Continuous, Flexible Natural Language Interaction with an Autonomous Robot
Brooks, Daniel J. (University of Massachusetts Lowell) | Lignos, Constantine (University of Pennsylvania) | Finucane, Cameron (Cornell University) | Medvedev, Mikhail S. (University of Massachusetts Lowell) | Perera, Ian (University of Rochester) | Raman, Vasumathi (Cornell University) | Kress-Gazit, Hadas (Cornell University) | Marcus, Mitch (University of Pennsylvania) | Yanco, Holly A. (University of Massachusetts Lowell)
While highly constrained language can be used for robot control, robots that can operate as fully autonomous subordinate agents communicating via rich language remain an open challenge. Toward this end, we developed an autonomous system that supports natural, continuous interaction with the operator through language before, during, and after mission execution. The operator communicates instructions to the system through natural language and is given feedback on how each instruction was understood as the system constructs a logical representation of its orders. While the plan is executed, the operator is updated on relevant progress via language and images and can change the robot's orders. Unlike many other integrated systems of this type, the language interface is built using robust, general purpose parsing and semantics systems that do not rely on domain-specific grammars. This system demonstrates a new level of continuous natural language interaction and a novel approach to using general-purpose language and planning components instead of hand-building for the domain. Language-enabled autonomous systems of this type represent important progress toward the goal of integrating robots as effective members of human teams.
Towards Using Discrete Multiagent Pathfinding to Address Continuous Problems
Krontiris, Athanasios (University of Nevada, Reno) | Sajid, Qandeel (University of Nevada, Reno) | Bekris, Kostas E (University of Nevada, Reno)
Motivated by efficient algorithms for solving combina- torial and discrete instances of the multi-agent pathfinding problem, this report investigates ways to utilize such solutions to solve similar problems in the continuous domain. While a simple discretization of the space which allows the direct application of combinatorial algorithms seems like a straightforward solution, there are additional constraints that such a discretization needs to satisfy in order to be able to provide some form of completeness guarantees in general configuration spaces. This report reviews ideas on how to utilize combinatorial algorithms to solve continuous multi-agent pathfinding problems. It aims to collect feedback from the community regarding the importance and the complexity of this challenge, as well as the appropriateness of the solutions considered here.
Relative Attributes for Enhanced Human-Machine Communication
Parikh, Devi (Toyota Technological Institute Chicago) | Kovashka, Adriana (University of Texas at Austin) | Parkash, Amar (IIIT-Delhi) | Grauman, Kristen (University of Texas at Austin)
We propose to model relative attributes that capture the relationships between images and objects in terms of human-nameable visual properties. For example, the models can capture that animal A is 'furrier' than animal B, or image X is 'brighter' than image B. Given training data stating how object/scene categories relate according to different attributes, we learn a ranking function per attribute. The learned ranking functions predict the relative strength of each property in novel images. We show how these relative attribute predictions enable a variety of novel applications, including zero-shot learning from relative comparisons, automatic image description, image search with interactive feedback, and active learning of discriminative classifiers. We overview results demonstrating these applications with images of faces and natural scenes. Overall, we find that relative attributes enhance the precision of communication between humans and computer vision algorithms, providing the richer language needed to fluidly "teach" a system about visual concepts.
Negotiation in Exploration-Based Environment
Sofer, Israel (Bar Ilan University) | Sarne, David (Bar Ilan University) | Hassidim, Avinatan (Bar Ilan University)
This paper studies repetitive negotiation over the execution of an exploration process between two self-interested, fully rational agents in a full information environmentwith side payments. A key aspect of the protocolis that the explorationโs execution may interleaves ith the negotiation itself, inflicting some degradationon the explorationโs flexibility. The advantage of this form of negotiation is in enabling the agents supervising that the explorationโs execution takes place in its agreedform as negotiated. We show that in many cases, much of the computational complexity of the new protocol can be eliminated by solving an alternative negotiation scheme according to which the parties first negotiate theexploration terms as a whole and then execute it. As demonstrated in the paper, the solution characteristics of the new protocol are somehow different from thoseof legacy negotiation protocols where the execution of the agreement reached through the negotiation is completely separated from the negotiation process. Furthermore, if the agents are given the option to control some of the negotiation protocol parameters, the resulting exploration may be suboptimal. In particular we show that the increase in an agentโs expected utility in such casesis unbounded and so is the resulting decrease in the social welfare. Surprisingly, we show that further increasingone of the agentsโ level of control in some of thenegotiation parameters enables bounding the resultingdecrease in the social welfare.
Colorization by Matrix Completion
Wang, Shusen (Zhejiang University) | Zhang, Zhihua (Zhejiang University)
Given a monochrome image and some manually labeled pixels, the colorization problem is a computer-assisted process of adding color to the monochrome image. This paper proposes a novel approach to the colorization problem by formulating it as a matrix completion problem. In particular, taking a monochrome image and parts of the color pixels (labels) as inputs, we develop a robust colorization model and resort to an augmented Lagrange multiplier algorithm for solving the model. Our approach is based on the fact that a matrix can be represented as a low-rank matrix plus a sparse matrix. Our approach is effective because it is able to handle the potential noises in the monochrome image and outliers in the labels. To improve the performance of our method, we further incorporate a so-called local-color-consistency idea into our method. Empirical results on real data sets are encouraging.
Context Tree Maximizing
Nguyen, Phuong Minh (Australian National University, NICTA) | Sunehag, Peter (Australian National University) | Hutter, Marcus (Australian National University, NICTA, ETHZ)
Recent developments in reinforcement learning for non-Markovianproblems witness a surge in history-based methods, among which weare particularly interested in two frameworks, PhiMDP and MC-AIXI-CTW. PhiMDP attempts to reduce the general RL problem, where the environment's states and dynamics are both unknown, toan MDP, while MC-AIXI-CTW incrementally learns a mixture of contexttrees as its environment model. The main idea of PhiMDP is toconnect generic reinforcement learning with classical reinforcementlearning. The first implementation of PhiMDP relies on astochastic search procedure for finding a tree that minimizes acertain cost function. This does not guarantee finding theminimizing tree, or even a good one, given limited search time. As aconsequence it appears that the approach has difficulties with largedomains. MC-AIXI-CTW is attractive in that it can incrementally andanalytically compute the internal model through interactions withthe environment. Unfortunately, it is computationally demanding dueto requiring heavy planning simulations at every single time step.We devise a novel approach called CTMRL, which analytically andefficiently finds the cost-minimizing tree. Instead of thecontext-tree weighting method that MC-AIXI-CTW is based on, we usethe closely related context-tree maximizing algorithm that selectsjust one single tree. This approach falls under the PhiMDPframework, which allows the replacement of the costly planningcomponent of MC-AIXI-CTW with simple Q-Learning. Our empiricalinvestigation show that CTMRL finds policies of quality as good as MC-AIXI-CTW's on sixdomains including a challenging Pacman domain, but in an order ofmagnitude less time.