In this paper, the author explores epistemological aspects of simulation with a particular focus on using simulations to provide recommendations to managers and other decision-makers. The author presents formal definitions of knowledge (as justified true belief) and of simulation. The author shows that a simple model, the Kuramoto model of coupled-oscillators, satisfies the simulation definition (and therefore generates knowledge) through a justified mapping from the real world. The author argues that, for more complex models, such a justified mapping requires three techniques: using an appropriate and justified theoretical construct; using appropriate and justified values for model parameters; and testing or other verification processes to ensure that the mapping is correctly defined. The author illustrates these three techniques with experiments and models from the literature, including the Long House Valley model of Axtell et al., the SAFTE model of sleep, and the Segregation model of Wilensky. Epistemological Aspects of Simulation Models for Decision Support
{"title":"Epistemological Aspects of Simulation Models for Decision Support","authors":"A. Dekker","doi":"10.4018/jats.2013040103","DOIUrl":"https://doi.org/10.4018/jats.2013040103","url":null,"abstract":"In this paper, the author explores epistemological aspects of simulation with a particular focus on using simulations to provide recommendations to managers and other decision-makers. The author presents formal definitions of knowledge (as justified true belief) and of simulation. The author shows that a simple model, the Kuramoto model of coupled-oscillators, satisfies the simulation definition (and therefore generates knowledge) through a justified mapping from the real world. The author argues that, for more complex models, such a justified mapping requires three techniques: using an appropriate and justified theoretical construct; using appropriate and justified values for model parameters; and testing or other verification processes to ensure that the mapping is correctly defined. The author illustrates these three techniques with experiments and models from the literature, including the Long House Valley model of Axtell et al., the SAFTE model of sleep, and the Segregation model of Wilensky. Epistemological Aspects of Simulation Models for Decision Support","PeriodicalId":93648,"journal":{"name":"International journal of agent technologies and systems","volume":"50 1","pages":"55-77"},"PeriodicalIF":0.0,"publicationDate":"2013-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88306881","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Agents evolving in complex and dynamic multi-agent systems need to plan their tasks and to adapt their behavior in order to react to unpredictable events. Therefore they must have plans that remain subject to continual updating, even during its execution. Although this property is important in dynamic environments, it is difficult to have a trade-off between the convergence towards the goal to be reached and the reaction to unanticipated events. To cope with this issue, it is needed to have a model allowing to represent plans less sensitive to execution contexts, and to support flexible execution. This paper aims to provide an adequate plan representation, by taking advantage of hierarchical plans and extensions to Petri net. The authors extend the Petri net to take into account the different abstraction levels of plans and the resources required by tasks. To cope with the interdependence of tasks, the authors include in the model, a synchronization mechanism between concurrent transitions. The proposed model can be used to reason on abstract levels of plans and to analyze, in a dynamic way, situations in which the execution of the plan can be performed in any ways, in some ways, or cannot be performed. Hierarchical Multi-Agent Plans Using Model-Based Petri Net
{"title":"Hierarchical Multi-Agent Plans Using Model-Based Petri Net","authors":"Said Brahimi, R. Maamri, Z. Sahnoun","doi":"10.4018/jats.2013040101","DOIUrl":"https://doi.org/10.4018/jats.2013040101","url":null,"abstract":"Agents evolving in complex and dynamic multi-agent systems need to plan their tasks and to adapt their behavior in order to react to unpredictable events. Therefore they must have plans that remain subject to continual updating, even during its execution. Although this property is important in dynamic environments, it is difficult to have a trade-off between the convergence towards the goal to be reached and the reaction to unanticipated events. To cope with this issue, it is needed to have a model allowing to represent plans less sensitive to execution contexts, and to support flexible execution. This paper aims to provide an adequate plan representation, by taking advantage of hierarchical plans and extensions to Petri net. The authors extend the Petri net to take into account the different abstraction levels of plans and the resources required by tasks. To cope with the interdependence of tasks, the authors include in the model, a synchronization mechanism between concurrent transitions. The proposed model can be used to reason on abstract levels of plans and to analyze, in a dynamic way, situations in which the execution of the plan can be performed in any ways, in some ways, or cannot be performed. Hierarchical Multi-Agent Plans Using Model-Based Petri Net","PeriodicalId":93648,"journal":{"name":"International journal of agent technologies and systems","volume":"20 1","pages":"1-30"},"PeriodicalIF":0.0,"publicationDate":"2013-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74686868","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper considers a class of systems of autonomous self-governed agents with purpose-specific behavior. Agents of this class contribute most to the overall performance if they have an unobstructed transparent access to the environment. Many examples of such systems can be found in swarm technologies and asynchronous simulation of discrete and continuous systems. An efficiency metric for a multi-agent system operating within a given environment is proposed as a dot product of the system's characteristic time-vectors: one of an agent's demands for resources and the other of the resources' availability. It is shown that the smaller the dot product the higher the efficiency of the agents. In some cases, the better efficiency of individual agents translates into improvement of the overall performance of the system. This observation is postulated as the principle of orthogonality: under some conditions, the asynchronous, ungoverned systems outperform the systems with synchronized actions. It is shown that the asynchronous "chaotic" multi-agent models, properly devised to achieve a higher level of transparency, can produce a better throughput beyond the level achieved by simply improving the latency of the system. Examples of orthogonal systems include many discrete-continuous physical, financial, control and some machine learning multi-agent models. Conditions of convergence of asynchronous models are presented. Some experimental results are shown, as well. More general observations are made in the context of natural decomposition.
{"title":"Asynchronous Modeling and Simulation with Orthogonal Agents","authors":"R. Tankelevich","doi":"10.4018/jats.2012100102","DOIUrl":"https://doi.org/10.4018/jats.2012100102","url":null,"abstract":"This paper considers a class of systems of autonomous self-governed agents with purpose-specific behavior. Agents of this class contribute most to the overall performance if they have an unobstructed transparent access to the environment. Many examples of such systems can be found in swarm technologies and asynchronous simulation of discrete and continuous systems. An efficiency metric for a multi-agent system operating within a given environment is proposed as a dot product of the system's characteristic time-vectors: one of an agent's demands for resources and the other of the resources' availability. It is shown that the smaller the dot product the higher the efficiency of the agents. In some cases, the better efficiency of individual agents translates into improvement of the overall performance of the system. This observation is postulated as the principle of orthogonality: under some conditions, the asynchronous, ungoverned systems outperform the systems with synchronized actions. It is shown that the asynchronous \"chaotic\" multi-agent models, properly devised to achieve a higher level of transparency, can produce a better throughput beyond the level achieved by simply improving the latency of the system. Examples of orthogonal systems include many discrete-continuous physical, financial, control and some machine learning multi-agent models. Conditions of convergence of asynchronous models are presented. Some experimental results are shown, as well. More general observations are made in the context of natural decomposition.","PeriodicalId":93648,"journal":{"name":"International journal of agent technologies and systems","volume":"9 1","pages":"17-37"},"PeriodicalIF":0.0,"publicationDate":"2012-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78997721","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Tasmanian devil population is being reduced in the wild at an alarming rate due to an epidemic, which is the result of an unusual disease mechanism. Infected animals "inject" cancer cells into other devils, which then clone the cells, developing tumors. These tumors are invariably fatal. Field observers have developed hypotheses that include a life-history change for the species. It is hypothesized that this change has the potential to improve the population's survivability. An agent-based model of Tasmanian devils is used to evaluate these hypotheses. The model results suggest that the devils' intra-gender aggression as well as their aggressive mating practices render the life-history change hypotheses' correctness improbable.
{"title":"An Agent-Based Model of the Spread of Devil Facial Tumor Disease in an Isolated Population of Tasmanian Devils","authors":"C. Knadler","doi":"10.4018/jats.2012100101","DOIUrl":"https://doi.org/10.4018/jats.2012100101","url":null,"abstract":"The Tasmanian devil population is being reduced in the wild at an alarming rate due to an epidemic, which is the result of an unusual disease mechanism. Infected animals \"inject\" cancer cells into other devils, which then clone the cells, developing tumors. These tumors are invariably fatal. Field observers have developed hypotheses that include a life-history change for the species. It is hypothesized that this change has the potential to improve the population's survivability. An agent-based model of Tasmanian devils is used to evaluate these hypotheses. The model results suggest that the devils' intra-gender aggression as well as their aggressive mating practices render the life-history change hypotheses' correctness improbable.","PeriodicalId":93648,"journal":{"name":"International journal of agent technologies and systems","volume":"80 1","pages":"1-16"},"PeriodicalIF":0.0,"publicationDate":"2012-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80035481","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The advances in Intelligent Transportation Systems ITS call for a new generation of traffic simulation models that support connectivity and collaboration among simulated vehicles and traffic infrastructure. In this paper we introduce MATISSE, a complex, large scale agent-based framework for the modeling and simulation of ITS and discuss how Alloy, a modeling language based on set theory and first order logic, was used to specify, verify, and analyze MATISSE's traffic models.
{"title":"On Modeling and Verification of Agent-Based Traffic Simulation Properties in Alloy","authors":"J. Valente, F. Araujo, Rym Zalila-Wenkstern","doi":"10.4018/jats.2012100103","DOIUrl":"https://doi.org/10.4018/jats.2012100103","url":null,"abstract":"The advances in Intelligent Transportation Systems ITS call for a new generation of traffic simulation models that support connectivity and collaboration among simulated vehicles and traffic infrastructure. In this paper we introduce MATISSE, a complex, large scale agent-based framework for the modeling and simulation of ITS and discuss how Alloy, a modeling language based on set theory and first order logic, was used to specify, verify, and analyze MATISSE's traffic models.","PeriodicalId":93648,"journal":{"name":"International journal of agent technologies and systems","volume":"3 1","pages":"38-60"},"PeriodicalIF":0.0,"publicationDate":"2012-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84436230","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The focus is an In Silico Liver ISL model family and an evolving suite of mechanistic hypotheses about rat liver-drug interactions. ISLs are multiscale and hierarchical. A medium grain Enzyme Induction mechanism was implemented. Validation falsification of complicated, knowledge-based models requires integrating distinct aspects and methods for multi-aspect validation. For ISLs, such integration has not been straightforward. Falsification is crucial for formulating, testing, and iteratively evolving hypotheses about liver mechanisms. During multi-aspect falsification, the authors can falsify a hypothesis in one aspect while simultaneously validating it in another aspect. The authors demonstrate a multi-scalar validation/falsification event in which they validate the mechanism against coarse grain measures of liver perfusate drug levels and falsify it against a medium grained measure of hepatic zonation. The authors also discuss how falsification is guiding mechanism hypothesis refinement. The ability to scale validation efforts is necessary for effective scientific use models such as ISLs.
{"title":"Falsifying an Enzyme Induction Mechanism within a Validated, Multiscale Liver Model","authors":"Glen E. P. Ropella, Tempus Dictum, R. Kennedy","doi":"10.4018/jats.2012070101","DOIUrl":"https://doi.org/10.4018/jats.2012070101","url":null,"abstract":"The focus is an In Silico Liver ISL model family and an evolving suite of mechanistic hypotheses about rat liver-drug interactions. ISLs are multiscale and hierarchical. A medium grain Enzyme Induction mechanism was implemented. Validation falsification of complicated, knowledge-based models requires integrating distinct aspects and methods for multi-aspect validation. For ISLs, such integration has not been straightforward. Falsification is crucial for formulating, testing, and iteratively evolving hypotheses about liver mechanisms. During multi-aspect falsification, the authors can falsify a hypothesis in one aspect while simultaneously validating it in another aspect. The authors demonstrate a multi-scalar validation/falsification event in which they validate the mechanism against coarse grain measures of liver perfusate drug levels and falsify it against a medium grained measure of hepatic zonation. The authors also discuss how falsification is guiding mechanism hypothesis refinement. The ability to scale validation efforts is necessary for effective scientific use models such as ISLs.","PeriodicalId":93648,"journal":{"name":"International journal of agent technologies and systems","volume":"126 1","pages":"1-14"},"PeriodicalIF":0.0,"publicationDate":"2012-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88164581","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}