Three fundamental pillars of multi-agent team formation (Doctoral Consortium)

Teams of voting agents are a powerful tool for solving complex problems. When forming such teams, there are three fundamental issues that must be addressed: (i) Selecting which agents should form a team; (ii) Aggregating the opinions of the agents; (iii) Assessing the performance of a team. In this thesis we address all these points

No robot left behind:coordination to overcome local minima in swarm navigation

In this paper, we address navigation and coordination methods that allow swarms of robots to converge and spread along complex 2D shapes in environments containing unknown obstacles. Shapes are modeled using implicit functions and a gradient descent approach is used for controlling the swarm. To overcome local minima, that may appear in these scenarios, we use a coordination mechanism that reallocates some robots as “rescuers” and sends them to help other robots that may be trapped. Simulations and real experiments demonstrate the feasibility of the proposed approach

Traffic control for a swarm of robots:avoiding target congestion

One of the main problems in the navigation of robotic swarms is when several robots try to reach the same target at the same time, causing congestion situations that may compromise performance. In this paper, we propose a distributed coordination algorithm to alleviate this type of congestion. Using local sensing and communication, and controlling their actions using a probabilistic finite state machine, robots are able to coordinate themselves to avoid these situations. Simulations and real experiments were executed to study the performance and effectiveness of the proposed algorithm. Results show that the algorithm allows the swarm to have a more efficient and smoother navigation and is suitable for large groups of robots

Traffic control for a swarm of robots:avoiding group conflicts

A very common problem in the navigation of robotic swarms is when groups of robots move into opposite directions, causing congestion situations that may compromise performance. In this paper, we propose a distributed coordination algorithm to alleviate this type of congestion. By working collaboratively, and warning their teammates about a congestion risk, robots are able to coordinate themselves to avoid these situations. We executed simulations and real experiments to study the performance and effectiveness of the proposed algorithm. Results show that the algorithm allows the swarm to navigate in a smoother and more efficient fashion, and is suitable for large groups of robots

Unleashing the power of multi-agent voting teams

Teams of voting agents have great potential in finding optimal solutions. However, there are fundamental challenges to effectively use such teams: (i) selecting agents; (ii) aggregating opinions; (iii) assessing performance. I address all these challenges, with theoretical and experimental contributions

Three fundamental pillars of decision-centered teamwork

This thesis introduces a novel paradigm in artificial intelligence: decision-centered teamwork. Decision-centered teamwork is the analysis of agent teams that iteratively take joint decisions into solving complex problems. Although teams of agents have been used to take decisions in many important domains, such as: machine learning, crowdsourcing, forecasting systems, and even board games; a study of a general framework for decisioncentered teamwork has never been presented in the literature before. I divide decision-centered teamwork in three fundamental challenges: (i) Agent Selection, which consists of selecting a set of agents from an exponential universe of possible teams; (ii) Aggregation of Opinions, which consists of designing methods to aggregate the opinions of different agents into taking joint team decisions; (iii) Team Assessment, which consists of designing methods to identify whether a team is failing, allowing a “coordinator” to take remedial procedures. In this thesis, I handle all these challenges. For Agent Selection, I introduce novel models of diversity for teams of voting agents. My models rigorously show that teams made of the best agents are not necessarily optimal, and also clarify in which situations diverse teams should be preferred. In particular, I show that diverse teams get stronger as the number of actions increases, by analyzing how the agents’ probability distribution function over actions changes. This has never been presented before in the ensemble systems literature. I also show that diverse teams have a great applicability for design problems, where the objective is to maximize the number of optimal solutions for human selection, combining for the first time social choice with number theory. All of these theoretical models and predictions are verified in real systems, such as Computer Go and architectural design. In particular, for architectural design I optimize the design of buildings with agent teams not only for cost and project requirements, but also for energy-efficiency, being thus an essential domain for sustainability. Concerning Aggregation of Opinions, I evaluate classical ranked voting rules from social choice in Computer Go, only to discover that plurality leads to the best results. This happens because real agents tend to have very noisy rankings. Hence, I create a ranking by sampling extraction technique, leading to significantly better results with the Borda voting rule. A similar study is also performed in the social networks domain, in the context of influence maximization. Additionally, I study a novel problem in social networks: I assume only a subgraph of the network is initially known, and we must spread influence and learn the graph simultaneously. I analyze a linear combination of two greedy algorithms, outperforming both of them. This domain has a great potential for health, as I run experiments in four real-life social networks from the homeless population of Los Angeles, aiming at spreading HIV prevention information. Finally, with regards to Team Assessment, I develop a domain independent team assessment methodology for teams of voting agents. My method is within a machine learning framework, and learns a prediction model over the voting patterns of a team, instead of learning over the possible states of the problem. The methodology is tested and verified in Computer Go and Ensemble Learning

Multi-agent team formation:solving complex problems by aggregating opinions (Doctoral Consortium)

It is known that we can aggregate the opinions of different agents to find high-quality solutions to complex problems. However, choosing agents to form a team is still a great challenge. Moreover, it is essential to use a good aggregation methodology in order to unleash the potential of a given team in solving complex problems. In my thesis, I present two different novel models to aid in the team formation process. Moreover, I propose a new methodology for extracting rankings from existing agents. I show experimental results both in the Computer Go domain and in the building design domain

Every team makes mistakes, in large action spaces

Voting is applied to better estimate an optimal answer to complex problems in many domains. We recently presented a novel benefit of voting, that has not been observed before: we can use the voting patterns to assess the performance of a team and predict whether it will be successful or not in problem-solving. Our prediction technique is completely domain independent, and it can be executed at any time during problem solving. In this paper we present a novel result about our technique: we show that the prediction quality increases with the size of the action space. We present a theoretical explanation for such phenomenon, and experiments in Computer Go with a variety of board sizes

Every team deserves a second chance:identifying when things go wrong (Student Abstract)

We show that without using any domain knowledge, we can predict the final performance of a team of voting agents, at any step towards solving a complex problem

Every team deserves a second chance:An Interactive 9x9 Go Experience (Demonstration)

We show that without using any domain knowledge, we can predict the final performance of a team of voting agents, at any step towards solving a complex problem. This demo allows users to interact with our system, and observe its predictions, while playing 9x9 Go