Didac Font - Academia.edu (original) (raw)

Papers by Didac Font

Research paper thumbnail of Multiagent Bidding Mechanisms for Robot Qualitative Navigation

This paper explores the use of bidding mechanisms to coordinate the actions requested by a group ... more This paper explores the use of bidding mechanisms to coordinate the actions requested by a group of agents in charge of achieving the task of guiding a robot towards a specified target in an unknown environment. This approach is based on a qualitative (fuzzy) approach to landmark-based navigation.

Research paper thumbnail of A Multi-agent Architecture Integrating Learning and Fuzzy Techniques for Landmark-Based Robot Navigation

Research paper thumbnail of A Multiagent Approach to Qualitative Landmark-Based Navigation

Auton. Robots, 2003

In this paper we present a multiagent system for landmark-based navigation in unknown environment... more In this paper we present a multiagent system for landmark-based navigation in unknown environments. We propose a bidding mechanism to coordinate the actions requested by the different agents. The navigation system has been tested on a real robot on indoor unstructured environments.

Research paper thumbnail of Managing Risk in Recurrent Auctions for Robust Resource Allocation

Auctions can be used to solve resource allocation problems where tasks have to be assigned to res... more Auctions can be used to solve resource allocation problems where tasks have to be assigned to resources in such a way that no resource gets overused and an objective function is optimized. In some cases a robust solution is preferable to the optimal solution as it may ...

Research paper thumbnail of Robustness in Recurrent Auctions for Resource Allocation

Resource allocation problems where resources have to be assigned to tasks in such a way that no r... more Resource allocation problems where resources have to be assigned to tasks in such a way that no resource gets overused can be solved using recurrent auctions. In dynamic environments where unexpected changes may occur, searching the optimal solution may not be the ...

Research paper thumbnail of Balancing Optimality and Robustness in Resource Allocation Problems

We formally define a flexible robustness mechanism for resource allocation problems encoded as co... more We formally define a flexible robustness mechanism for resource allocation problems encoded as combinatorial auctions based on repairable solutions. Our notion of robustness is focused on resources that become unavailable once an allocation has been found. We extend ...

Research paper thumbnail of A Micro-Meso-Macro Approach to Intelligent Transportation Systems

ABSTRACT Despite all the technological advances in the automotive industry and the high instrumen... more ABSTRACT Despite all the technological advances in the automotive industry and the high instrumentation of road infrastructures, driving a vehicle is still a stressful and polluting operation. In order to achieve a more sustainable use of vehicles, in this paper we propose a three-layered (micro-meso-macro) framework that provides intelligence at different levels of detail of the driving experience. At the micro level, intelligence is provided to the individual vehicle, at the meso level, intelligence is concerned with local clusters of vehicles and group decision making, and at the macro level, intelligence is provided so that system-wide goals are achieved. We illustrate each of these levels with a particular implementation, although alternative implementations may be used as well. Namely, we use an affective anticipatory architecture for the micro level, a consensus algorithm at the meso level, and a resource allocation mechanism together with electronic institutions for the macro level. We believe that the combination of intelligences at each of the levels may lead to a more efficient and sustainable use of the vehicles and the infrastructure.

Research paper thumbnail of Animation of Self-Organising Resource Allocation Using Presage2

ABSTRACT This paper presents a demonstration of Presage2, a general purpose platform for developi... more ABSTRACT This paper presents a demonstration of Presage2, a general purpose platform for developing animation and simulations of collective adaptive systems.

Research paper thumbnail of Self-Organising Common-Pool Resource Allocation and Canons of Distributive Justice

Two principles of enduring institutions for selforganising resource allocation are congruence of ... more Two principles of enduring institutions for selforganising resource allocation are congruence of the allocation method to the resources available, and participation of those affected by the allocation (the appropriators) in selecting that method. However, the principles do not say anything explicitly about the fairness of the allocation method, or the outcomes. In this paper, we complement these principles with canons of distributive justice represented as legitimate claims, which are implemented as voting functions that determine the order in which resource requests are satisfied. The appropriators vote on the weight attached to the scoring functions, and so selforganise the allocation method. Experiments with a variation of the Linear Public Good game show that this pluralistic selforganising approach produces a better balance of utility and fairness (for agents that comply with the rules of the game) than monistic or fixed approaches.

Research paper thumbnail of Formal Models of Social Processes: The Pursuit of Computational Justice in Self-Organising Multi-Agent Systems

ABSTRACT This SASO tutorial is concerned with the pursuit of computational justice in and for sel... more ABSTRACT This SASO tutorial is concerned with the pursuit of computational justice in and for self-organising systems. We contend that many aspects of self-organisation in open systems and socio-technical systems -- such as representation in collective choice arrangements, fairness in resource provision and appropriation, rewards and sanctions for compliance and non-compliance with regulations, quality assessment of self-organised structures and processes --are all underpinned by some notion of justice. We propose computational justice as an interdisciplinary research programme at an intersection between computer science and social sciences, enabling and promoting an exchange of ideas and results in both directions. The aim of this tutorial is to provide students and researchers of self-organising systems with an introduction to the idea of computational justice, its motivation, concepts, tools, methods and applications -- and many open questions.

Research paper thumbnail of Strategies for Exploiting Trust Models in Competitive Multi-Agent Systems

Lecture Notes in Computer Science, 2009

Multi-agent systems where agents compete against one another in a specific environment pose chall... more Multi-agent systems where agents compete against one another in a specific environment pose challenges in relation to the trust modeling of an agent aimed at ensuring the right decisions are taken. A lot of literature has focused on describing trust models, but less in developing strategies to use them optimally. In this paper we propose a decision-making strategy that uses the information provided by the trust model to take the best decisions to achieve the most benefits for the agent. This decision making tackles the exploration versus exploitation problem since the agent has to decide when to interact with the known agents and when to look for new ones. The experiments were performed using the ART Testbed, a simulator created with the goal of objectively evaluate different trust strategies. The agent competed in and won the Third International ART Testbed Competition held in Estoril (Portugal) in March 2008.

Research paper thumbnail of Reinforcement learning for landmark-based robot navigation

Proceedings of the first international joint conference on Autonomous agents and multiagent systems part 2 - AAMAS '02, 2002

Research paper thumbnail of Socially distributed perception

Proceeding of the 1st ACM SIGCHI/SIGART conference on Human-robot interaction - HRI '06, 2006

This paper presents a robot search task (social tag) that uses social interaction, in the form of... more This paper presents a robot search task (social tag) that uses social interaction, in the form of asking for help, as an integral component of task completion. We define socially distributed perception as a robot's ability to augment its limited sensory capacities through social interaction. We review previous work in robots that are helped by humans, social situatedness, and socially distributed cognition. We discuss the task of social tag and its implementation on GRACE for the AAAI 2005 Robot Exhibition. We then present observations and results that suggest that we were successful in promoting a form of social interaction that allowed people to help the robot achieve its goal. Finally, we discuss the implications of this design approach for effective and compelling human-robot interaction.

Research paper thumbnail of Dynamic Configurable Auctions for Coordinating Industrial Waste Discharges

Lecture Notes in Computer Science, 2007

The use of auctions for distributing resources in competing environments has produced a large var... more The use of auctions for distributing resources in competing environments has produced a large variety of auctions types and algorithms to treat them. However, auctions have some problems when faced with some real-world applications containing renewable and perishable resources. In this paper we present a mechanism to deal with such issues by dynamically configuring some of the auction parameters taking into account the past experience. The mechanism has been used to coordinate industrial discharges and a Waste Water Treatment Plant, so that the treatment thresholds of the plant are never exceeded. We have performed some simulations to evaluate the system, and the results show that with this mechanism the coordination between the industries improves the treatment of the water.

Research paper thumbnail of Developing Strategies for the ART Domain

Lecture Notes in Computer Science, 2010

Abstract. In this paper we propose the design of an agent for the ART Testbed, a tool created wit... more Abstract. In this paper we propose the design of an agent for the ART Testbed, a tool created with the goal of objectively evaluate different trust strategies. The agent design includes a trust model and a strategy for decision making. The trust model is based on the three ...

Research paper thumbnail of A Fair Mechanism for Recurrent Multi-unit Auctions

Lecture Notes in Computer Science, 2008

Auctions are a good tool for dealing with resource allocation in multi-agent environments. When t... more Auctions are a good tool for dealing with resource allocation in multi-agent environments. When the resources are either renewable or perishable resources, a repeated auction mechanism is needed, in what is known as recurrent auctions. However, several problems arise with this kind of auction, namely, the resource waste problem, the bidder drop problem, and the asymmetric balance of negotiation power. In this paper we present different mechanisms to deal with these issues. We have evaluated the mechanisms in a network bandwidth allocation scenario, and the results show that the proposed mechanisms achieve higher benefits for the auctioneer, while also providing a fairer behavior.

Research paper thumbnail of Evolving a multiagent system for landmark-based robot navigation

International Journal of Intelligent Systems, 2005

In this article, we build upon a multiagent architecture for landmark-based navigation in unknown... more In this article, we build upon a multiagent architecture for landmark-based navigation in unknown environments. In this architecture, each of the agents in the navigation system has a bidding function that is controlled by a set of parameters. We show here the good results obtained by an evolutionary approach that tunes the parameter set values for two navigation tasks.

Research paper thumbnail of A Multiagent System for Coordinating Ambulances for Emergency Medical Services

IEEE Intelligent Systems, 2000

This system uses an auction mechanism based on trust to select an ambulance for emergency patient... more This system uses an auction mechanism based on trust to select an ambulance for emergency patient transportation.

Research paper thumbnail of Fairness in Recurrent Auctions With Competing Markets and Supply Fluctuations

Computational Intelligence, 2012

Auctions have been used to deal with resource allocation in multiagent environments, especially i... more Auctions have been used to deal with resource allocation in multiagent environments, especially in serviceoriented electronic markets. In this type of market, resources are perishable and auctions are repeated over time with the same or a very similar set of agents. In this scenario it is advisable to use recurrent auctions: a sequence of auctions of any kind where the result of one auction may influence the following one. Some problems do appear in these situations, as for instance, the bidder drop problem, the asymmetric balance of negotiation power or resource waste, which could cause the market to collapse. Fair mechanisms can be useful to minimize the effects of these problems. With this aim, we have analyzed four previous fair mechanisms under dynamic scenarios and we have proposed a new one that takes into account changes in the supply as well as the presence of alternative marketplaces. We experimentally show how the new mechanism presents a higher average performance under all simulated conditions, resulting in a higher profit for the auctioneer than with the previous ones, and in most cases avoiding the waste of resources. 1 When we use the term "reservation price" we refer to the minimum price at which the auctioneer is willing to sell a resource. We assume that this value is private to the auctioneer and bidders do not know it.

Research paper thumbnail of Socially Distributed Perception: GRACE plays social tag at AAAI 2005

Autonomous Robots, 2007

This paper presents a robot search task (social tag) that uses social interaction, in the form of... more This paper presents a robot search task (social tag) that uses social interaction, in the form of asking for help, as an integral component of task completion. Socially distributed perception is defined as a robot's ability to augment its limited sensory capacities through social interaction. We describe the task of social tag and its implementation on the robot GRACE for the AAAI 2005 Mobile Robot Competition & Exhibition. We then discuss our observations and analyses of GRACE's performance as a situated interaction with conference participants. Our results suggest we were successful in promoting a form of social interaction that allowed people to help the robot achieve its goal. Furthermore, we found that different social uses of the physical space had an effect on the nature of the interaction. Finally, we discuss the implications of this design approach for effective and compelling human-robot interaction, considering its relationship to concepts such as dependency, mixed initiative, and socially distributed cognition.

Research paper thumbnail of Multiagent Bidding Mechanisms for Robot Qualitative Navigation

This paper explores the use of bidding mechanisms to coordinate the actions requested by a group ... more This paper explores the use of bidding mechanisms to coordinate the actions requested by a group of agents in charge of achieving the task of guiding a robot towards a specified target in an unknown environment. This approach is based on a qualitative (fuzzy) approach to landmark-based navigation.

Research paper thumbnail of A Multi-agent Architecture Integrating Learning and Fuzzy Techniques for Landmark-Based Robot Navigation

Research paper thumbnail of A Multiagent Approach to Qualitative Landmark-Based Navigation

Auton. Robots, 2003

In this paper we present a multiagent system for landmark-based navigation in unknown environment... more In this paper we present a multiagent system for landmark-based navigation in unknown environments. We propose a bidding mechanism to coordinate the actions requested by the different agents. The navigation system has been tested on a real robot on indoor unstructured environments.

Research paper thumbnail of Managing Risk in Recurrent Auctions for Robust Resource Allocation

Auctions can be used to solve resource allocation problems where tasks have to be assigned to res... more Auctions can be used to solve resource allocation problems where tasks have to be assigned to resources in such a way that no resource gets overused and an objective function is optimized. In some cases a robust solution is preferable to the optimal solution as it may ...

Research paper thumbnail of Robustness in Recurrent Auctions for Resource Allocation

Resource allocation problems where resources have to be assigned to tasks in such a way that no r... more Resource allocation problems where resources have to be assigned to tasks in such a way that no resource gets overused can be solved using recurrent auctions. In dynamic environments where unexpected changes may occur, searching the optimal solution may not be the ...

Research paper thumbnail of Balancing Optimality and Robustness in Resource Allocation Problems

We formally define a flexible robustness mechanism for resource allocation problems encoded as co... more We formally define a flexible robustness mechanism for resource allocation problems encoded as combinatorial auctions based on repairable solutions. Our notion of robustness is focused on resources that become unavailable once an allocation has been found. We extend ...

Research paper thumbnail of A Micro-Meso-Macro Approach to Intelligent Transportation Systems

ABSTRACT Despite all the technological advances in the automotive industry and the high instrumen... more ABSTRACT Despite all the technological advances in the automotive industry and the high instrumentation of road infrastructures, driving a vehicle is still a stressful and polluting operation. In order to achieve a more sustainable use of vehicles, in this paper we propose a three-layered (micro-meso-macro) framework that provides intelligence at different levels of detail of the driving experience. At the micro level, intelligence is provided to the individual vehicle, at the meso level, intelligence is concerned with local clusters of vehicles and group decision making, and at the macro level, intelligence is provided so that system-wide goals are achieved. We illustrate each of these levels with a particular implementation, although alternative implementations may be used as well. Namely, we use an affective anticipatory architecture for the micro level, a consensus algorithm at the meso level, and a resource allocation mechanism together with electronic institutions for the macro level. We believe that the combination of intelligences at each of the levels may lead to a more efficient and sustainable use of the vehicles and the infrastructure.

Research paper thumbnail of Animation of Self-Organising Resource Allocation Using Presage2

ABSTRACT This paper presents a demonstration of Presage2, a general purpose platform for developi... more ABSTRACT This paper presents a demonstration of Presage2, a general purpose platform for developing animation and simulations of collective adaptive systems.

Research paper thumbnail of Self-Organising Common-Pool Resource Allocation and Canons of Distributive Justice

Two principles of enduring institutions for selforganising resource allocation are congruence of ... more Two principles of enduring institutions for selforganising resource allocation are congruence of the allocation method to the resources available, and participation of those affected by the allocation (the appropriators) in selecting that method. However, the principles do not say anything explicitly about the fairness of the allocation method, or the outcomes. In this paper, we complement these principles with canons of distributive justice represented as legitimate claims, which are implemented as voting functions that determine the order in which resource requests are satisfied. The appropriators vote on the weight attached to the scoring functions, and so selforganise the allocation method. Experiments with a variation of the Linear Public Good game show that this pluralistic selforganising approach produces a better balance of utility and fairness (for agents that comply with the rules of the game) than monistic or fixed approaches.

Research paper thumbnail of Formal Models of Social Processes: The Pursuit of Computational Justice in Self-Organising Multi-Agent Systems

ABSTRACT This SASO tutorial is concerned with the pursuit of computational justice in and for sel... more ABSTRACT This SASO tutorial is concerned with the pursuit of computational justice in and for self-organising systems. We contend that many aspects of self-organisation in open systems and socio-technical systems -- such as representation in collective choice arrangements, fairness in resource provision and appropriation, rewards and sanctions for compliance and non-compliance with regulations, quality assessment of self-organised structures and processes --are all underpinned by some notion of justice. We propose computational justice as an interdisciplinary research programme at an intersection between computer science and social sciences, enabling and promoting an exchange of ideas and results in both directions. The aim of this tutorial is to provide students and researchers of self-organising systems with an introduction to the idea of computational justice, its motivation, concepts, tools, methods and applications -- and many open questions.

Research paper thumbnail of Strategies for Exploiting Trust Models in Competitive Multi-Agent Systems

Lecture Notes in Computer Science, 2009

Multi-agent systems where agents compete against one another in a specific environment pose chall... more Multi-agent systems where agents compete against one another in a specific environment pose challenges in relation to the trust modeling of an agent aimed at ensuring the right decisions are taken. A lot of literature has focused on describing trust models, but less in developing strategies to use them optimally. In this paper we propose a decision-making strategy that uses the information provided by the trust model to take the best decisions to achieve the most benefits for the agent. This decision making tackles the exploration versus exploitation problem since the agent has to decide when to interact with the known agents and when to look for new ones. The experiments were performed using the ART Testbed, a simulator created with the goal of objectively evaluate different trust strategies. The agent competed in and won the Third International ART Testbed Competition held in Estoril (Portugal) in March 2008.

Research paper thumbnail of Reinforcement learning for landmark-based robot navigation

Proceedings of the first international joint conference on Autonomous agents and multiagent systems part 2 - AAMAS '02, 2002

Research paper thumbnail of Socially distributed perception

Proceeding of the 1st ACM SIGCHI/SIGART conference on Human-robot interaction - HRI '06, 2006

This paper presents a robot search task (social tag) that uses social interaction, in the form of... more This paper presents a robot search task (social tag) that uses social interaction, in the form of asking for help, as an integral component of task completion. We define socially distributed perception as a robot's ability to augment its limited sensory capacities through social interaction. We review previous work in robots that are helped by humans, social situatedness, and socially distributed cognition. We discuss the task of social tag and its implementation on GRACE for the AAAI 2005 Robot Exhibition. We then present observations and results that suggest that we were successful in promoting a form of social interaction that allowed people to help the robot achieve its goal. Finally, we discuss the implications of this design approach for effective and compelling human-robot interaction.

Research paper thumbnail of Dynamic Configurable Auctions for Coordinating Industrial Waste Discharges

Lecture Notes in Computer Science, 2007

The use of auctions for distributing resources in competing environments has produced a large var... more The use of auctions for distributing resources in competing environments has produced a large variety of auctions types and algorithms to treat them. However, auctions have some problems when faced with some real-world applications containing renewable and perishable resources. In this paper we present a mechanism to deal with such issues by dynamically configuring some of the auction parameters taking into account the past experience. The mechanism has been used to coordinate industrial discharges and a Waste Water Treatment Plant, so that the treatment thresholds of the plant are never exceeded. We have performed some simulations to evaluate the system, and the results show that with this mechanism the coordination between the industries improves the treatment of the water.

Research paper thumbnail of Developing Strategies for the ART Domain

Lecture Notes in Computer Science, 2010

Abstract. In this paper we propose the design of an agent for the ART Testbed, a tool created wit... more Abstract. In this paper we propose the design of an agent for the ART Testbed, a tool created with the goal of objectively evaluate different trust strategies. The agent design includes a trust model and a strategy for decision making. The trust model is based on the three ...

Research paper thumbnail of A Fair Mechanism for Recurrent Multi-unit Auctions

Lecture Notes in Computer Science, 2008

Auctions are a good tool for dealing with resource allocation in multi-agent environments. When t... more Auctions are a good tool for dealing with resource allocation in multi-agent environments. When the resources are either renewable or perishable resources, a repeated auction mechanism is needed, in what is known as recurrent auctions. However, several problems arise with this kind of auction, namely, the resource waste problem, the bidder drop problem, and the asymmetric balance of negotiation power. In this paper we present different mechanisms to deal with these issues. We have evaluated the mechanisms in a network bandwidth allocation scenario, and the results show that the proposed mechanisms achieve higher benefits for the auctioneer, while also providing a fairer behavior.

Research paper thumbnail of Evolving a multiagent system for landmark-based robot navigation

International Journal of Intelligent Systems, 2005

In this article, we build upon a multiagent architecture for landmark-based navigation in unknown... more In this article, we build upon a multiagent architecture for landmark-based navigation in unknown environments. In this architecture, each of the agents in the navigation system has a bidding function that is controlled by a set of parameters. We show here the good results obtained by an evolutionary approach that tunes the parameter set values for two navigation tasks.

Research paper thumbnail of A Multiagent System for Coordinating Ambulances for Emergency Medical Services

IEEE Intelligent Systems, 2000

This system uses an auction mechanism based on trust to select an ambulance for emergency patient... more This system uses an auction mechanism based on trust to select an ambulance for emergency patient transportation.

Research paper thumbnail of Fairness in Recurrent Auctions With Competing Markets and Supply Fluctuations

Computational Intelligence, 2012

Auctions have been used to deal with resource allocation in multiagent environments, especially i... more Auctions have been used to deal with resource allocation in multiagent environments, especially in serviceoriented electronic markets. In this type of market, resources are perishable and auctions are repeated over time with the same or a very similar set of agents. In this scenario it is advisable to use recurrent auctions: a sequence of auctions of any kind where the result of one auction may influence the following one. Some problems do appear in these situations, as for instance, the bidder drop problem, the asymmetric balance of negotiation power or resource waste, which could cause the market to collapse. Fair mechanisms can be useful to minimize the effects of these problems. With this aim, we have analyzed four previous fair mechanisms under dynamic scenarios and we have proposed a new one that takes into account changes in the supply as well as the presence of alternative marketplaces. We experimentally show how the new mechanism presents a higher average performance under all simulated conditions, resulting in a higher profit for the auctioneer than with the previous ones, and in most cases avoiding the waste of resources. 1 When we use the term "reservation price" we refer to the minimum price at which the auctioneer is willing to sell a resource. We assume that this value is private to the auctioneer and bidders do not know it.

Research paper thumbnail of Socially Distributed Perception: GRACE plays social tag at AAAI 2005

Autonomous Robots, 2007

This paper presents a robot search task (social tag) that uses social interaction, in the form of... more This paper presents a robot search task (social tag) that uses social interaction, in the form of asking for help, as an integral component of task completion. Socially distributed perception is defined as a robot's ability to augment its limited sensory capacities through social interaction. We describe the task of social tag and its implementation on the robot GRACE for the AAAI 2005 Mobile Robot Competition & Exhibition. We then discuss our observations and analyses of GRACE's performance as a situated interaction with conference participants. Our results suggest we were successful in promoting a form of social interaction that allowed people to help the robot achieve its goal. Furthermore, we found that different social uses of the physical space had an effect on the nature of the interaction. Finally, we discuss the implications of this design approach for effective and compelling human-robot interaction, considering its relationship to concepts such as dependency, mixed initiative, and socially distributed cognition.