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Constitutive and Regulative Specifications of Commitment Protocols: A Decoupled Approach (Extended Abstract)

AAAI Conferences

A clear separation of the constitutive from the regulative specification would bring many advantages, mostly as direct We analyze the emerging trends from research on effects of the obtained modularity: easier reuse of actions in multi-agent interaction protocols, on workflows and different contexts, easier customization on the protocol, easier on business processes. We propose a definition of composition of protocols. As a consequence, MAS would gain commitment-based interaction protocols, characterized greater openness, interoperability, and modularity of design.


Exploiting Separability in Multiagent Planning with Continuous-State MDPs (Extended Abstract)

AAAI Conferences

Decentralized partially observable Markov decision processes (Dec-POMDPs) provide a general model for decision-making under uncertainty in cooperative decentralized settings, but are difficult to solve optimally (NEXP-Complete). As a new way of solving these problems, we recently introduced a method for transforming a Dec-POMDP into a continuous-state deterministic MDP with a piecewise-linear and convex value function. This new Dec-POMDP formulation, which we call an occupancy MDP, allows powerful POMDP and continuous-state MDP methods to be used for the first time. However, scalability remains limited when the number of agents or problem variables becomes large. In this paper, we show that, under certain separability conditions of the optimal value function, the scalability of this approach can increase considerably. This separability is present when there is locality of interaction between agents, which can be exploited to improve performance. Unlike most previous methods, the novel continuous-state MDP algorithm retains optimality and convergence guarantees. Results show that the extension using separability can scale to a large number of agents and domain variables while maintaining optimality.


The Complexity of Model Checking Succinct Multiagent Systems

AAAI Conferences

This paper studies the complexity of model checking multiagent systems, in particular systems succinctly described by two practical representations: concurrent representation and symbolic representation. The logics we concern include branching time temporal logics and several variants of alternating time temporal logics.


Dynamic Execution of Temporal Plans with Sensing Actions and Bounded Risk

AAAI Conferences

This thesis focuses on the problem of temporal planning under uncertainty with explicit safety guarantees, which are enforced by means of chance constraints. We aim at elevating the level in which operators interact with autonomous agents and specify their desired behavior, while retaining a keen sensitivity to risk. Instead of relying on unconditional sequences, our goal is to allow contingent plans to be dynamically scheduled and conditioned on observations of the world while remaining safe. Contingencies add flexibility by allowing goals to be achieved through different methods, while observations allow the agent to adapt to the environment. We demonstrate the usefulness of our chance-constrained temporal planning approaches in real-world applications, such as partially observable power supply restoration and collaborative human-robot manufacturing.


Efficient Methods for Multi-Objective Decision-Theoretic Planning

AAAI Conferences

In decision-theoretic planning problems, such as (partially observable) Markov decision problems or coordination graphs, agents typically aim to optimize a scalar value function. However, in many real-world problems agents are faced with multiple possibly conflicting objectives. In such multi-objective problems, the value is a vector rather than a scalar, and we need methods that compute a coverage set, i.e., a set of solutions optimal for all possible trade-offs between the objectives. In this project propose new multi-objective planning methods that compute the so-called convex coverage set (CCS): the coverage set for when policies can be stochastic, or the preferences are linear. We show that the CCS has favorable mathematical properties, and is typically much easier to compute that the Pareto front, which is often axiomatically assumed as the solution set for multi-objective decision problems.


On the Testability of BDI Agent Systems (Extended Abstract)

AAAI Conferences

Before deploying a software system we need to assure ourselves (and stakeholders) that the system will behave correctly. This assurance is usually done by testing the system. However, it is intuitively obvious that adaptive systems, including agent-based systems, can exhibit complex behaviour, and are thus harder to test. In this paper we examine this "obvious intuition" in the case of Belief-Desire-Intention (BDI) agents, by analysing the number of paths through BDI goal-plan trees. Our analysis confirms quantitatively that BDI agents are hard to test, sheds light on the role of different parameters, and highlights the enormous difference made by failure handling.


An Intelligent and Unified Framework for Multiple Robot and Human Coalition Formation

AAAI Conferences

This dissertation develops the intelligent-Coalition Formation framework for Humans and Robots (i-CiFHaR), an intelligent decision making frameworkfor multi-agent coalition formation. i-CiFHaR is a first of its kind that incorporates a library of coalition formation algorithms; employs unsupervised learning to mine crucial patterns among these algorithms; and leverages probabilistic reasoning to derive the most appropriate algorithm(s) to apply in accordance with multiple mission criteria. The dissertation also contributes to the state-of-the-art in swarm intelligence by addressing the search stagnation limitation of existing ant colony optimization algorithms (ACO) by integrating the simulated annealing mechanism. The experimental results demonstrate that the presented hybrid ACO algorithms significantly outperformed the best existing ACO approaches, when applied to three NP-complete optimization problems (e.g., traveling salesman problem, maximal clique problem, multi-agent coalition formation problem).


Quantifying and Improving the Robustness of Trust Systems

AAAI Conferences

Trust systems are widely used to facilitate interactions among agents based on trust evaluation. These systems may have robustness issues, that is, they are affected by various attacks. Designers of trust systems propose methods to defend against these attacks. However, they typically verify the robustness of their defense mechanisms (or trust models) only under specific attacks. This raises problems: first, the robustness of their models is not guaranteed as they do not consider all attacks. Second, the comparison between two trust models depends on the choice of specific attacks, introducing bias. We propose to quantify the strength of attacks, and to quantify the robustness of trust systems based on the strength of the attacks it can resist.Our quantification is based on information theory, and provides designers of trust systems a fair measurement of the robustness.


Norms as a Basis for Governing Sociotechnical Systems: Extended Abstract

AAAI Conferences

We understand a sociotechnical system as a microsociety in which autonomous parties interact with and about technical objects. We define governance as the administration of such a system by its participants. We develop an approach for governance based on a computational representation of norms. Our approach has the benefit of capturing stakeholder needs precisely while yielding adaptive resource allocation in the face of changes both in stakeholder needs and the environment. We are currently extending this approach to address the problem of secure collaboration and to contribute to the emerging science of cybersecurity.


Unleashing the Power of Multi-Agent Voting Teams

AAAI Conferences

Such prediction is important to take remedy procedures to increase a team's performance. Existing Teams of voting agents have great potential in finding methods are tailored for specific domains [Ramos and optimal solutions. However, there are fundamental Ayanegui, 2008]. In Nagarajan et al. [2015] I introduce a challenges to effectively use such teams: (i) novel domain independent technique, which learns a prediction selecting agents; (ii) aggregating opinions; (iii) assessing function using only the voting patterns of a team.