Franco Cicirelli

Agent-Based Control Framework In Jade.

This paper proposes an agent-based control framework in JADE which allows the construction of control extensions tailored to the application needs. The approach is based on a minimal actor model which simplifies JADE agent programming. A catalog of reusable control forms, both concurrent/parallel and time-dependent (real time or simulation time are supported) was achieved. The paper introduces the control framework, clarifies its implementation status and demonstrates its practical use

A Component-Based Architecture For Modelling And Simulation Of Adaptive Complex Systems

This paper proposes a component-based software architecture (Theatre) hosted by Java, which enables modelling and discrete-event simulation of complex and dynamically reconfigurable systems, possibly on top of a distributed computing context. At the “programming in-the-small” level, Theatre rests on light-weight reactive components (actors or agents) which interact to one another by asynchronous message-passing. Actor behaviour is modelled by a finite state machine. Actors can be easily composed to create new reusable components. At the “programming in-the-large” level a subsystem of actors can be assigned to an execution locus (theatre). A theatre provides to local agents the basic message scheduling, dispatching, communication and mobility services. The paper describes componentbased M&S support of Theatre and demonstrates its practical use through examples.

Modelling and Analysis of Parallel/Distributed Time-dependent Systems: An Approach Based on JADE

The work described in this paper develops a control framework for modelling and analysis of parallel/distributed time-dependent multi-agent systems. The approach centres on a minimal computational model which separates agent behaviours from schedulable actions which model activities which have a time duration and require specific processing units. Different control strategies ranging from pure concurrent to time sensitive (real-time or simulated-time) can be considered and applied as a plug-in to a multi-agent system. The control framework is tailored to the JADE distributed agent infrastructure, which lacks of any built-in solution for developing time-dependent applications. This paper focusses on the achievement of control strategies for schedulability analysis of embedded real-time systems designed to execute on a multicore/distributed context. As a case study, a real-time tasking set is modelled and analyzed through simulation, which requires flexible computational resources.

Distributing RePast Simulations Using Actors.

RePast is a well-known agent-based toolkit for modelling and simulation of complex systems. The toolkit is normally used on a single workstation, where modelling, execution and visualization aspects are dealt with. This paper describes an approach aimed to distributing RePast models, with minimal changes, over a networked context so as to address very large and reconfigurable models whose computational needs (in space and time) can be difficult to satisfy on a single machine. Novel in the approach is an exploitation of a lean actor infrastructure implemented in Java. Actors bring to RePast agents migration, location-transparent naming, efficient communications, and a control-centric framework. Actors can be orchestrated by an in-thelarge custom control structure which can ensure the necessary message precedence constraints. Preliminary experience is being carried out using HLA/RTI as middleware. However, the realization can also work with other standard transport layers such as Java Socket and Java RMI. The paper introduces the design rationale behind mapping RePast on to actors and discusses a distributed example.

Agent Methodological Layers In Repast Simphony.

Repast Simphony (RS) is a popular toolbox for agentbased modeling and simulation (ABMS) of complex systems. It can be used from within the Eclipse IDE with Java being the main implementation language. Moreover, visual modeling is supported by agent flowcharts. Powerful features of RS include contexts and projections which allow the modeler to build e.g. situated multi-agent systems (MAS) which can easily be configured and visualized in the RS runtime system. RS lacks of a reference agent methodology. Rather the modeler is free to define and follow her/his own methodology with RS: procedurally, declaratively or visual-based. This openness was exploited in this work for supporting different notions of agents, thus addressing the modeling needs of various application domains. In particular this paper proposes an embed in RS of an actor model which provides a lightweight notion of agents. The actor model is then used as a kernel for supporting more abstract but rigorous modeling languages like Parallel DEVS (P−DEVS) and time-extended Petri nets. A P−DEVS modeling example is reported to demonstrate the usefulness of supporting multiple agent methodological layers in RS.

Agents Over The Grid: An Experience Using The Globus Toolkit 4.

This paper describes an experience of porting the THEATRE agent architecture on top of the grid. The agent architecture consists of light-weight actors and computational theatres which have been proven to be well suited for modeling and simulation of complex systems. THEATRE nodes act as agencies that provide common services of message scheduling and dispatching to mobile actors. THEATRE is currently implemented in Java and can work with different transport layers and middleware. In the last years it was successfully interfaced to HLA/RTI, Terracotta, Java Sockets and Java RMI. The work described in this paper aims at experimenting with THEATRE over the grid, using in particular the Globus toolkit. The goal is to open THEATRE to the exploitation of virtual organizations of computing resources with secure communications, and to favor simulation interoperability through grid services. The paper summarizes THEATRE, describes a design and prototype implementation of THEATRE on top of the Globus Toolkit 4 (GT4), and demonstrates its practical use by means of a modeling example.

Modelling And Verification Of Concurrent Programs Using UPPAAL.

This paper describes the design and implementation of a library of reusable UPPAAL template processes which support reasoning and property checking of concurrent programs, e.g. to be realized in the Java programming language. The stimulus to the development of the library originated in the context of a systems programming undergraduate course. The library, though, can be of help to general practitioners of concurrent programming which nowadays are challenged to exploiting the potentials of modern multicore architectures. The paper describes the library and demonstrates its usage to modelling and exhaustive verification of mutual exclusion and common concurrent structures and synchronizers. UPPAAL was chosen because it is a popular and continually improved toolbox based on timed automata and model checking and it is provided of a user-friendly graphical interface which proves very important for debugging and property assessment of concurrent models. Java was considered as target implementation language because of its diffusion among application developers.

A Smartphone Application For The Monitoring Of Domestic Consumption Of Electricity.

The work presented in this paper concerns the development of a smartphone application for the monitoring of energy consumption relative to a domestic electricity grid. An algorithm has been integrated in the smartphone application allowing Enel (the main Italian Electrical Company) customers to have, on their mobile phone, clear and transparent information about the energy consumption of their houses in real time.

Dynamic Sociality Minority Game.

The minority game (MG) is a simple yet effective binarydecision model which is well suited to study the collective emerging behaviour in a population of agents with bounded and inductive rationality when they have to compete, through adaptation, for scarce resources. The original formulation of the MG was inspired by the W.B. Arthur’s El Farol Bar problem in which a fixed number of people have to independently decide each week whether to go to a bar having a limited capacity. A decision is only affected by information on the number of visitors who attended the bar in the past weeks. In its basic version, the MG does not contemplate communication among players and it supposes that information about the past game outcomes is publicly available. This paper proposes the Dynamic Sociality Minority Game (DSMG), an original variant of the classic MG where (i) information about the outcome of the previously played game step is assumed to be known only by the agents that really attended the bar the previous week and (ii) a dynamically established acquaintance relationship is introduced to propagate such information among non attendant players. Particular game settings are identified which make DSMG able to exhibits a better coordination level among players with respect to standard MG. Behavioral properties of the DSMG are thoroughly analyzed through an agent-based simulation of a simple road-traffic model. INTRODUCTION The Minority Game (MG) (Challet and Zhang, 1997) is an inductive game born as a mathematical formulation of the El Farol Bar attendance problem (Arthur, 1994). The problem refers to a scenario in which a fixed number of people have to decide about making use of a shared resource represented by a bar. Since the space in the bar is limited (finite resources), the sojourn is considered enjoyable only if the number of attendances remains under a specified threshold. Basic formulation of MG considers N (supposed odd) players that make a choice between two options at each turn, e.g. to attend the bar or to stay home. Winners are those that belong to the minority side, i.e. that chosen by at most (n − 1)/2 players. Each player is initially fed with a fixed and randomly chosen set of strategies that it may use to calculate its next choice on the basis only of the past outcomes of the game. The game generalizes the study of how many individuals, competing in a resource constrained environment, may reach a collective solution to a problem under adaptation of each one’s expectation about the future without resorting to cooperation strategies. MG proved to be effective in many application fields like economics, biology and social science. In (Lustosa and Cajueiro, 2010) the game is applied in a scenario tied to market of goods being auctioned. In (Cicirelli et al., 2007) MG is exploited for developing protocols controlling the coverage level in large wireless sensor networks. Applications related to predator/prey models and traffic scenarios can be found respectively in (Cicirelli et al., 2011) and (Bazzan et al., 2000)(Chmura and Pitz, 2006). The game has been the subject of extensive study (Challet et al., 2005) and the original model has been modified in various ways (Sysi-Aho, 2005). Adaptive minority game models, in which agents try to improve their performances by modifying their strategies through genetic algorithm based on crossover mechanisms, are discussed in (Sysi-Aho et al., 2004). The concept of agent personality is used in (Bazzan et al., 2000) where players are equipped with a selected combination of game strategies trying to model certain types of human behaviour. Social relationships among players are considered in (Remondino and Cappellini, 2005). Here it is introduced the concept of Local Minority Game where each player owns a local view of the game and it will win or lose a game step on the basis of the decisions taken by the players belonging to its acquaintances. Each game step is divided in two phases: in the first phase each player undertakes a non-committed choice which is made available to the acquaintances, in the second phase each player uses such shared information to commit its previously made choice or definitively change it. In this approach the established social relations cannot change dynamically. The Constrained Information Minority Game (CIMG) (Lustosa and Cajueiro, 2010) shares with the work proposed in this paper the basic idea that the only players Proceedings 25th European Conference on Modelling and Simulation ©ECMS Tadeusz Burczynski, Joanna Kolodziej Aleksander Byrski, Marco Carvalho (Editors) ISBN: 978-0-9564944-2-9 / ISBN: 978-0-9564944-3-6 (CD) who surely know the outcome of the last turn of the game are those who actually attended the bar. This is a realistic hypothesis because it considers that, in a population, information about a happening propagates in a different way. In the CIMG, though, it is assumed that not attendant players may become aware of the last game outcome only on the basis of a fixed probability. In this paper, the Dynamic Sociality Minority Game (DSMG) is proposed. DSMG assumes that (i) information about the outcome of the previously played game step is only known by players that really attended the bar and (ii) a dynamically established acquaintance relationship is available to propagate such information among non attendant players. Here it is argued that the capability of exploiting dynamic sociality behavior is an important issue for modeling scenarios arising in the daily life in a more realistic way. For instance, supposing that a player can move over a territory, it becomes possible to take into account situations where acquaintances depend on the specific position owned by a player during a game step. Moreover the number of acquaintances may change over the time and may be related also to the ability of a player to establish (or to keep alive) social relations with other people in its nearness. Behavioral properties of DSMG are studied by using a modelling example based on a simple road traffic scenario. A single road connecting two places, e.g. a city and a resort, is considered. People have to decide if to go on holyday or returning home avoiding traffic. DSMG analysis is carried out through agent based simulation (Macal and North, 2006)(Wickenberg and Davidsson, 2003). The Theatre agency (Cicirelli et al., 2009) is used for implementing the game. Simulation results show that game settings exist which make DSMG able to exhibits a better coordination level among players with respect to standard MG. Moreover, when the number of acquaintances reduces, the game results not organized around the socially optimal point, for instance this means that the road in the adopted example may be underutilized on the average, and arbitrage opportunities may arise (Lustosa and Cajueiro, 2010). The rest of the paper is structured as follows. First the definition of the DSMG is provided, then its behavioural properties are discussed through the road traffic model. Finally, conclusions are given with an outlook of future work. DYMANIC SOCIALITY MINORITY GAME In the basic formulation of MG (Challet and Zhang, 1997), N (supposed odd) players make a binary choice attempting to be in the minority side. Each player is initially fed with a randomly chosen set S of strategies that it uses to calculate its next choice on the basis only of the past M outcomes of the game. Since there are only two possible outcomes, M is also the number of bits needed to store the history of the game. The number of possible histories is of course P = 2 , strategies are numerable and their number is 2 . Players rank their own strategies based on their respective capability to predict the winner side. Every player associates each strategy with a virtual score which is incremented every time the strategy, if applied, would have predicted the minority side. A penalty is instead assigned to bad behaving strategies. At each game step, a player uses the first ranked strategy. When there is a tie among possible strategies, the player chooses randomly among them. Standard MG assumes that information about last game step is publicly available. As a consequence the same history exists for all players. At each game step, DSMG groups players in three categories named participant (PA), informed (IN) and noninformed (NI). PA are those players that really attended the bar and directly know the game outcome. IN represents players that although did not go to the bar, they indirectly know the game outcome through their social network. NI denotes non-attendant players which remain unaware of the last game outcome. NI players are not able to update their strategies nor their history. As a consequence, players in the DSMG may accumulate a different history and may have a different view on the whole game status. DSMG can be formally defined as in the following. Let O = {−1, +1} be the set of possible outcomes of the game, PL be the set of players and I be a subset of natural numbers corresponding to the game steps. Let h : PL× I → O be the function modelling the history of a player, i.e. h(p, i) returns the last M outcomes of the game of player p, preceding a given game step i; h(p, 0) is randomly set for each player. Let S = {S1, . . . , Sn} be the set of all allowed strategies and Sj : O → O be a strategy function which guesses the next winner side by looking at the game history. Let str : PL × I → N be the function which returns the index of the strategy used by player p at the game step i. The outcome of a player p at game step i is given by S str(p,i). Once all players have defined their choice at step i, the sum of these choices defines the outcome of that step: A(i) = ∑ p∈PL S h(p,i) str(p,i). Let Acq : PL×I → 2 be a function determining the set of acquaintances of player p at the game step i, and Cat : PL × I → {PA, IN, NI} be the function which determines the category of player p at game step i: Cat

Global And Local Synchronization In Parallel Space-Aware Applications.

Space-aware applications are characterized by an explicit representation of a spatial environment in which some entities live and operate by interacting with each other and with the hosting territory. A relevant space-aware application domain is the so-called urban computing, embracing issues like the simulation and implementation of public transportation systems, traffic management, urban monitoring and control. The execution of such applications is often distributed on parallel computing nodes, which need to cooperate and exchange data among each other, thus raising synchronization issues. In this paper we analyze time-related characteristics of the computational process in a space-aware application in the case when each node does not need global synchronization (i.e. synchronization with all other nodes) but requires only local synchronization (i.e. synchronization with a subset of neighbor nodes). Performance is evaluated both analytically and numerically. We provide the analytical support to an important conclusion: the mean computation time per step remains finite irrespective of the number of nodes under local synchronization, while under global synchronization it grows unboundedly as the number of nodes increases. In practical scenarios this corresponds to significantly better scalability properties of local synchronization.