dr. Syed Waqar Jaffry

Publications:

Names of the authors are in alphabetical order and all can be regarded as having made a comparable contribution, exceptions are marked with *

Journal
1. Hoogendoorn, M., Jaffry, S.W., and Treur, J., Cognitive and Neural Modeling of Dynamics of Trust in Competitive Trustees. In: Cognitive Systems Research Journal.(CSR), vol. 14, Elsevier B. V., 2012, pp. 60-83. DOI (preliminary version)
   • Title: "Cognitive and Neural Modeling of Dynamics of Trust in Competitive Trustees."
     Authors: Hoogendoorn, M., Jaffry, S.W., and Treur, J.
     
     Abstract
     Trust dynamics can be modeled in relation to experiences. In this paper two models to represent human trust dynamics are introduced, namely a model on a cognitive level and a neural model. These models each include a number of parameters, providing the possibility to express certain relations between trustees. The behavior of each of the models is further analyzed by means of simulation experiments and formal verification techniques. Thereafter, both models have been compared to see whether they can produce patterns that are comparable. As each of the models has its own specific set of parameters, with values that depend on the type of person modeled, such a comparison is nontrivial. To address this, a special comparison approach is introduced, based on mutual mirroring of the models in each other. More specifically, for a given parameter values set for one model, by an automated parameter estimation procedure the most optimal values for the parameter values of the other model are determined in order to show the same behavior. Roughly spoken the results are that the models can mirror each other up to an accuracy of around 90%.
2. Bosse, T., Both, F., Hoogendoorn, M., Jaffry, S.W., Lambalgen, R. van, Oorburg, R., Sharpanskykh, R., Treur, J., and Vos, M. de, Design and Validation of a Model for a Human's Functional State and Performance. In: International Journal of Modeling, Simulation, and Scientific Computing,(IJMSSC), vol. 2, no. 4, World Scientific Publishing, 2011, pp. 413-443. DOI (preliminary version)
   • Title: "Design and Validation of a Model for a Human's Functional State and Performance."
     Authors: Bosse, T., Both, F., Hoogendoorn, M., Jaffry, S.W., Lambalgen, R. van, Oorburg, R., Sharpanskykh, R., Treur, J., and Vos, M. de.
     
     Abstract
     This paper presents a computational model of the dynamics of a human?s functional state in relation to task performance and environment. It can be used in intelligent systems that support humans in demanding circumstances. The model takes task demand and situational aspects as input and determines internal factors such as the experienced pressure, exhaustion and motivation, and how they affect performance. Simulation experiments under different parameter settings pointed out that the model is able to produce realistic behavior of different types of personalities. Moreover, by a mathematical analysis the equilibria of the model have been determined, and by automated checking a number of expected properties of the model have been confirmed. In addition to the internal validation of the model, an experiment has been designed for the purpose of external validation addressing the estimation of the for the application relevant aspects of the human process. Output from the experiment like personality characteristics and performance quality has been used to perform estimation of the parameters of the model. By the parameter estimation a set of parameter values has been identified by which an adequate representation of a person?s functional state when performing a task is achieved.
3. Bosse, T., Gerritsen, C., Hoogendoorn, M., Jaffry, S.W., and Treur, J., Agent-Based versus Population-Based Simulation of Displacement of Crime: A Comparative Study. In: Web Intelligence and Agent Systems Journal, (WAIS), vol. 9, no. 2, IOS Press, 2011, pp. 147-160. DOI (preliminary version)
   • Title: "Agent-Based versus Population-Based Simulation of Displacement of Crime: A Comparative Study."
     Authors: Bosse, T., Gerritsen, C., Hoogendoorn, M., Jaffry, S.W., and Treur, J.
     
     Abstract
     Central research questions addressed within Criminology are how the geographical displacement of crime can be understood, explained, and predicted. The process of crime displacement is usually explained by referring to the interaction of three types of agents: criminals, passers-by, and guardians. Most existing simulation models of this process take a 'local' perspective, i.e., they are agent-based. However, when the number of agents considered becomes large, more 'global' approaches, such as population-based simulation have computational advantages over agent-based simulation. This article presents both an agent-based and a population-based simulation model of crime displacement, and reports a comparative evaluation of the two models. In addition, an approach is put forward to analyse the behaviour of both models by means of formal techniques. The results suggest that under certain conditions, population-based models approximate agent-based models, at least in the domain under investigation.
   Conference

4. Jaffry, S.W., and Treur, J., Modelling Trust for Communicating Agents: Agent-Based and Population-Based Perspectives. In: Jedrzejowicz, P., Nguyen, N.T., Hoang, K. (eds.), Proceedings of the Third International Conference on Computational Collective Intelligence,. (ICCCI'11), Gdynia, (Poland), Part I. Lecture Notes in Artifical Intelligence, vol. 6922. Springer Verlag, 2011, pp. 366-377.
   • Title: "Modelling Trust for Communicating Agents: Agent-Based and Population-Based Perspectives."
     Authors: Jaffry, S.W., and Treur, J.,
     
     Abstract
     This paper presents an exploration of the differences between agent-based and population-based models for trust dynamics. This exploration is based on both a large variety of simulation experiments and a mathematical analysis of the equilibria of the two types of models. The outcomes show that the differences between the models are not very substantial, and become less for larger numbers of agents.
5. Hoogendoorn, M., Jaffry, S.W., Maanen, P.P. van, and Treur, J., Modeling and Validation of Biased Human Trust. In: Boissier, O., et al. (eds.), Proceedings of the 11th IEEE/WIC/ACM International Conference on Intelligent Agent Technology,. (IAT'11), Lyon, (France), IEEE Computer Society Press, 2011, pp. 256-263.
   • Title: "Modeling and Validation of Biased Human Trust."
     Authors: Hoogendoorn, M., Jaffry, S.W., Maanen, P.P. van, and Treur, J.,
     
     Abstract
     When considering intelligent agents that interact with humans, having an idea of the trust levels of the human, for example in other agents or services, can be of great importance. Most models of human trust that exist, are based on some rationality assumption, and biased behavior is not represented, whereas a vast literature in Cognitive and Social Sciences indicates that humans often exhibit non-rational, biased behavior with respect to trust. This paper reports how some variations of biased human trust models have been designed, analyzed and validated against empirical data. The results show that such biased trust models are able to predict human trust significantly better.
6. Hoogendoorn, M., Jaffry, S.W., and Maanen, P.-P. van., Validation and Verification of Agent Models for Trust: Independent compared to Relative Trust. Proceedings of the 5th IFIP WG 11.11 International Conference on Trust Management.. (TM'11), Copenhagen, (Denmark), June 29th - July 1st, 2011. International Federation of Information Processing, Advances in Information and Communication Technology Series, Springer Verlag, 2011, vol. 358, pp. 35-50.
   • Title: "Validation and Verification of Agent Models for Trust: Independent compared to Relative Trust."
     Authors: Hoogendoorn, M., Jaffry, S.W., and Maanen, P.-P. van.,
     
     Abstract
     In this paper, the results of a validation experiment for two existing computational trust models describing human trust are reported. One model uses experiences of performance in order to estimate the trust in different trustees. The second model carries the notion of relative trust. The idea of relative trust is that trust in a certain trustee not solely depends on the experiences with that trustee, but also on trustees that are considered competitors of that trustee. In order to validate the models, parameter adaptation has been used to tailor the models towards human behavior. A comparison between the two models has also been made to see whether the notion of relative trust describes human trust behavior in a more accurate way. The results show that taking trust relativity into account indeed leads to a higher accuracy of the trust model. Finally, a number of assumptions underlying the two models are verified using an automated verification tool.
7. Hoogendoorn, M., Jaffry, S.W., and Treur, J., Exploration and Exploitation in Adaptive Trust-Based Decision Making in Dynamic Environments. In: Huang, X.J., Ghorbani, A.A., Hacid, M.-S., Yamaguchi, T. (eds.) Proceedings of the 10th IEEE/WIC/ACM International Conference on Intelligent Agent Technology,. (IAT'10), Toronto, (Canada), August 31st - September 3rd, 2010. IEEE Computer Society Press, 2010, pp. 256-260. DOI (preliminary version)
   • Title: "Exploration and Exploitation in Adaptive Trust-Based Decision Making in Dynamic Environments."
     Authors: Hoogendoorn, M., Jaffry, S.W., and Treur, J.,
     
     Abstract
     Trust is generally considered an important aspect in the decision making of agents. In the literature, a variety of computational models for trust have been proposed that also express how an agent can make a decision by exploiting the trust levels it has for the different options. Within such a decision making mechanism the focus is usually on a single most trusted option, which as a side effect may lead to a lack of information on the other options over time. Therefore it may sometimes be worthwhile to be more explorative in the decision making, especially to adapt to dynamic environments. In this paper an adaptive trust-based decision making model is proposed that varies the extent of exploration and exploitation in the agent's decisions. The model is evaluated and compared to other existing models by means of simulations.
8. Hoogendoorn, M., Jaffry, S.W., and Treur, J., Incorporating Interdependency of Trust Values in Existing Models for Trust Dynamics. In: Nishigaki, M., Josang, A., Murayama, Y., Marsh, S. (eds.), Trust Management IV, Proceedings of the 4th International Conference on Trust Management, Advances in Information and Communication Technology,. (TM'10), Morioka, Iwate, (Japan), June 16th - 18th, 2010. Advances in Information and Communication Technology, vol. 321. Springer Verlag, 2010, pp. 263-276. DOI (preliminary version)
   • Title: "Incorporating Interdependency of Trust Values in Existing Models for Trust Dynamics."
     Authors: Hoogendoorn, M., Jaffry, S.W., and Treur, J.,
     
     Abstract
     Many models of trust consider the trust an agent has in another agent (the trustee) as the result of experiences with that specific agent in combination with certain personality attributes. For the case of multiple trustees, there might however be dependencies between the trust levels in different trustees. In this paper, two alternatives are described to model such dependencies: (1) development of a new trust model which incorporates dependencies explicitly, and (2) an extension of existing trust models that is able to express these interdependencies using a translation mechanism from objective experiences to subjective ones. For the latter, placing the interdependencies in the experiences enables the reuse of existing trust models that typically are based upon certain experiences over time as input. Simulation runs are performed using the two approaches, showing that both are able to generate realistic patterns of interdependent trust values.
9. Both, F., Hoogendoorn, M., Jaffry. S.W., Lambalgen, R. van, Oorburg, R., Sharpanskykh, A., Treur, J., and Vos, M. de, Adaptation and Validation of an Agent Model of Functional State and Performance for Individuals. In: Yang, J.-J.; Yokoo, M.; Ito, T.; Jin, Z.; Scerri, P. (eds.), Proceedings of 12th International Conference on Principles of Practice in Multi-Agent Systems. (PRIMA'09), Nagoya, (Japan), December 13th - 16th, 2009. Lecture Notes in Artificial Intelligence, vol. 5925, Springer Verlag, 2009, pp. 595-607. DOI (preliminary version)
   • Title: "Adaptation and Validation of an Agent Model of Functional State and Performance for Individuals."
     Authors: Both, F., Hoogendoorn, M., Jaffry. S.W., Lambalgen, R. van, Oorburg, R., Sharpanskykh, A., Treur, J., and Vos, M. de,
     
     Abstract
     Human performance can seriously degrade under demanding tasks. To improve performance, agents can reason about the current state of the human, and give the most appropriate and effective support. To enable this, the agent needs a model of a specific person's functional state and performance, which should be valid, as the agent might otherwise give inappropriate advice and even worsen performance. This paper concerns the adaptation of the parameters of the existing functional state model to the individual and validation of the resulting model. First, human experiments have been designed and conducted, whereby measurements related to the model have been performed. Next, this data has been used to obtain appropriate parameter settings for the model, describing the specific subject. Finally,the model, with the tailored parameter settings, has been used to predict human behavior to investigate predictive capabilities of the model. The results have been analyzed using formal verification.
10. Jaffry, S.W., and Treur, J., Comparing a Cognitive and a Neural Model for Relative Trust Dynamics. In: Leung, C.S., Lee, M., and Chan, J.H. (eds.), Proceedings of 16th International Conference on Neural Information Processing. (ICONIP'09), Bangkok, (Thailand), December 1st - 5th, 2009. Lecture Notes in Computer Science, vol. 5863 Part I, Springer Verlag, 2009, pp. 72-83. DOI (preliminary version)
    • Title: "Comparing a Cognitive and a Neural Model for Relative Trust Dynamics."
      Authors: Jaffry, S.W., and Treur, J.,
      
      Abstract
      Trust dynamics can be modelled in relation to experiences. Both cognitive and neural models for trust dynamics in relation to experiences are available, but were not yet related or compared in more detail. This paper presents a comparison between a cognitive and a neural model. As each of the models has its own specific set of parameters, with values that depend on the type of person modelled, such a comparison is nontrivial. In this paper a comparison approach is presented that is based on mutual mirroring of the models in each other. More specifically, for given parameter values set for one model, by automated parameter estimation processes the most optimal values for the parameter values of the other model are determined to show the same behavior. Roughly spoken the results are that the models can mirror each other up to an accuracy of around 90%.
11. Hoogendoorn, M., Jaffry, S.W., and Treur, J., Modelling Trust Dynamics from a Neurological Perspective. In: Wang, R., Gu, F. (eds.), Advances in Cognitive Neurodynamics II, Proceedings of the 2nd International Conference on Cognitive Neurodynamics. (ICCN'09), Hangzhou, (China), November 15th - 19th, 2009. Springer Verlag, 2011, pp. 523-536. DOI (preliminary version)
    • Title: "Modelling Trust Dynamics from a Neurological Perspective."
      Authors: Hoogendoorn, M., Jaffry, S.W., and Treur, J.,
      
      Abstract
      Trust is often assumed to depend on experiences. Models for the dynamics of trust in relation to experiences usually have a cognitive nature, leaving affective aspects out of consideration. However, neurological findings show more and more how in mental processes cognitive and affective aspects are intertwined. In this paper, by adopting neurological theories on the role of emotions and feelings, a model for trust dynamics is introduced incorporating the relation between trust and feeling. The model makes use of a Hebbian learning principle and describes how trust does not only depend on experiences viewed as information obtained over time, but also on emotional responses and feelings related to experiences.
12. Hoogendoorn, M., Jaffry, S.W., and Treur, J., An Adaptive Agent Model Estimating Human Trust in Information Sources. In: Baeza-Yates, R., Lang, J., Mitra, S., Parsons, S., Pasi, G. (eds.), Proceedings of the 9th IEEE/WIC/ACM International Conference on Intelligent Agent Technology, . (IAT'09), Milan, (Italy), September 15th - 18th, 2009. IEEE Computer Society Press, 2009, pp. 458-465. DOI (preliminary version)
    • Title: "An Adaptive Agent Model Estimating Human Trust in Information Sources."
      Authors: Hoogendoorn, M., Jaffry, S.W., and Treur, J.,
      
      Abstract
      For an information agent to support a human in a personalized way, having a model of the trust the human has in information sources may be essential. As humans differ a lot in their characteristics with respect to trust, a trust model crucially depends on specific personalized values for a number of parameters. This paper contributes an adaptive agent model for trust with parameters that are automatically tuned over time to a specific individual. To obtain the adaptation, four different techniques have been developed. In order to evaluate these techniques, simulations have been performed. The results of these were formally verified.
13. Hoogendoorn, M., Jaffry. S.W., The Influence of Personalities upon the Dynamics of Trust and Reputation. In: Proceedings of International Symposium on Secure Computing (SecureCom'09), in conjunction with the IEEE International Conference on Privacy, Security, Risk and Trust, (PASSAT'09), Vancouver, (Canada), August 29th - 31st, 2009. IEEE Computer Society Press, 2009 pp. 263-270. DOI (preliminary version)
    • Title: "The Influence of Personalities upon the Dynamics of Trust and Reputation."
      Authors: Hoogendoorn, M., Jaffry. S.W.,
      
      Abstract
      When an agent resides in a community, the opinion of other community members concerning whether a particular individual is trustworthy or not influences the trust level of this agent. Hereby, the precise influence depends on the personality of the agent (e.g. whether he lets his opinion be influenced by others a lot). In this paper, a computational trust model which has dedicated parameters for agent personalities is applied to such a social context. A variety of different communities (containing agents with different personalities) have hereby been simulated. The resulting patterns hereof are shown in this paper. Furthermore, the simulation results are formally analyzed to show that certain patterns do occur in all different communities.
14. Bosse, T., Gerritsen, C., Hoogendoorn, M., Jaffry, S.W., and Treur, J., Comparison of Agent-Based and Population-Based Simulations of Displacement of Crime. In: Jain, L., Gini, M., Faltings, B.B., Terano, T., Zhang, C., Cercone, N., Cao, L. (eds.), Proceedings of the 8th IEEE/WIC/ACM International Conference on Intelligent Agent Technology, (IAT'08), Sydney, (Australia), December 9th - 12th, 2008. IEEE Computer Society Press, 2008, pp. 469-476. DOI (preliminary version)
    • Title: "Comparison of Agent-Based and Population-Based Simulations of Displacement of Crime."
      Authors: Bosse, T., Gerritsen, C., Hoogendoorn, M., Jaffry, S.W., and Treur, J.
      
      Abstract
      Within Criminology, the process of crime displacement is usually explained by referring to the interaction of three types of agents: criminals, passers-by, and guardians. Most existing simulation models of this process are agent-based. However, when the number of agents considered becomes large, population-based simulation has computational advantages over agent-based simulation. This paper presents both an agent-based and a population-based simulation model of crime displacement, and reports a comparative evaluation of the two models. In addition, an approach is put forward to analyse the behaviour of both models by means of formal techniques.
15. Jaffry, S.W., Treur, J., Agent-Based and Population-Based Simulation: A Comparative Case Study for Epidemics. In: Proceedings of the 22nd European Conference on Modelling and Simulation,(ECMS'08), Nicosia, (Cyprus), June 3rd - 6th, 2008. European Council on Modeling and Simulation, 2008, pp. 123-130. (preliminary version)
    • Title: "Agent-Based and Population-Based Simulation: A Comparative Case Study for Epidemics."
      Authors: Jaffry, S.W., Treur, J.
      
      Abstract
      This paper reports a comparative evaluation of population-based simulation in comparison to agentbased simulation for different numbers of agents. Population-based simulation, such as for example in the classical approaches to predator-prey modelling and modelling of epidemics, has computational advantages over agent-based modelling with large numbers of agents. Therefore the latter approaches can be considered useful only when the results are expected to deviate from the results of population-based simulation, and are considered more realistic. However, there is sometimes also a silent assumption that for larger numbers of agents, agent-based simulations approximate population-based simulations, which would indicate that agent-based simulation just can be replaced by population-based simulation. The paper evaluates this assumption by a detailed comparative case study in epidemics.
16. * Jaffry, S. W., Kayyani, U. R., FOSS Localization: A Solution for The ICT Dilemma of Developing Countries. In: Proceedings of 9th International IEEE MultiTopic Conference, (INMIC'05) , Karachi (Pakistan), December 24th - 25th 2005. Institute of Electrical and Electronics Engineers, pp. 1-5. DOI (preliminary version)
    • Title: "FOSS Localization: A Solution for The ICT Dilemma of Developing Countries"
      Authors: Jaffry, S. W., Kayyani, U. R.
      
      Abstract
      Information and communication technology (ICT) has tremendously expanded over the last three decades making the access to right information at the right time feasible ensuring the success of an individual, organization or culture. In order to make the most out of this exciting revolution one must be in a position to afford and completely comprehend what is offered by this technology. Unfortunately most of the software are controlled by proprietary that are economically unaffordable for developing countries and are based on language that is not comprehendible by their masses. Software localization of Free and Open Source Software (FOSS) is an effort that addresses this twofold dilemma. FOSS made software affordable while localization bridges the language barrier that helps people to fully comprehend and utilize the benefits of ICT. In this research we have explored various aspects of the software localization of free and open source operating system (FOSOS) and developed a working prototype. Paper explains concept and all the technical steps of FOSS localization of Ubuntu Linux that is a FOSOS with a foreseeable future work.
17. * Jaffry, S. W., Pedagogical Pattern Language for in Time Student Confidence in Studied Material. In: Proceeding of 9th International IEEE MultiTopic Conference, (INMIC'05) , Karachi (Pakistan), December 24th - 25th 2005. Institute of Electrical and Electronics Engineers, pp. 1-6. DOI (preliminary version)
    • Title: "Pedagogical Pattern Language for in Time Student Confidence in Studied Material"
      Authors: Jaffry, S. W.
      
      Abstract
      Over the past few years, importing design patterns from software engineering to the computer science education (CSE) is followed by defining patterns and pattern languages suitable for pedagogical needs of Computer Science courses. The main goal of patterns incorporation in CSE was to enhance quality of content delivery and comprehension. However it is observed that soon after learning a concept most of the students are not certain about the degree of command over the studied material. Lack of questioning power makes it more devastating. The existing pattern-based materials seem to be insufficient for settling these problems. Hence there is a requirement of pedagogical pattern language that have twofold power of resolving these issues. This paper presents a pedagogical pattern language based on three newly discovered pedagogical patterns to address in time students confidence in their level of comprehension about learned skills.
18. * Idrees, M., Yousaf, M. M., Jaffry, S. W., Pasha, M. A., Hussain, S. A., Enhancements in AODV Routing Using Mobility Aware Agents. In: Proceedings of IEEE International Conference on Emerging Technologies, (ICET'05), Islamabad (Pakistan), September 16th - 17th 2005. Institute of Electrical and Electronics Engineers, pp. 98-102. DOI (preliminary version)
    • Title: "Enhancements in AODV Routing Using Mobility Aware Agents"
      Authors: Idrees, M., Yousaf, M. M., Jaffry, S. W.,  Pasha, M. A., Hussain, S. A.
      
      Abstract
      In infrastructure-less mobile and ad-hoc networks the routes have to be refreshed oftenly due to the mobility of the nodes acting as routers. If a node is aware of the mobility of neighboring nodes, the highly mobile node can be avoided to be the part of routes and ultimately reduces the re-route discoveries. This paper introduces mobility aware agents in ad-hoc network nodes and modifies HELLO packets of the AODV protocol to enhance mobility awareness. Mobility aware agent can update its awareness through inquiry and reply to inquiries about neighbors on quasi-periodic bases. On receiving the HELLO packet with GPS coordinates of the originator, agent compares them with previous ones and hence has awareness about the mobility of the originator with reference to itself. The enhancements in the throughput of the network are studied through simulation in OPNET that has shown optimistic results.
    Workshop

19. Hoogendoorn, M., Jaffry, S.W., and Treur, J., Modeling Dynamics of Relative Trust of Competitive Information Agents. In: Klusch, M., Pechoucek, M., Polleres, A. (eds.), Proc. of the 12th International Workshop on Cooperative Information Agents, (CIA'08), Prague, (Czech Republic), September 10th - 12th, 2008. Lecture Notes in Artificial Intelligence, vol. 5180, Springer Verlag, 2008, pp. 55-70. DOI (preliminary version)
    • Title: "Modeling Dynamics of Relative Trust of Competitive Information Agents."
      Authors: Hoogendoorn, M., Jaffry, S.W., and Treur, J.
      
      Abstract
      In order for personal assistant agents in an ambient intelligence context to provide good recommendations, or pro-actively support humans in task allocation, a good model of what the human prefers is essential. One aspect that can be considered to tailor this support to the preferences of humans is trust. This measurement of trust should incorporate the notion of relativeness since a personal assistant agent typically has a choice of advising substitutable options. In this paper such a model for relative trust is presented, whereby a number of parameters can be set that represent characteristics of a human.
    Extended Abstract and Poster

20. Both, F., Hoogendoorn, M., Jaffry. S.W., Lambalgen, R. van, Oorburg, R., Sharpanskykh, A., Treur, J., and Vos, M. de, Validation of an Agent Model for Human Work Pressure (Poster). Presented at the 9th International Conference on Cognitive Modeling, (ICCM'09), Manchester, (United Kingdom), July 24th - 26th, 2009.
    • Title: "Validation of an Agent Model for Human Work Pressure."
      Authors: Both, F., Hoogendoorn, M., Jaffry. S.W., Lambalgen, R. van, Oorburg, R., Sharpanskykh, A., Treur, J., and Vos, M. de,
      
      Abstract
      Human performance can seriously degrade under demanding tasks. To improve performance, agents can reason about the current state of the human, and give the most appropriate and effective support. To enable this, the agent needs a work pressure model, which should be valid, as the agent might otherwise give inappropriate advice and even worsen performance. This paper concerns the validation of an existing work pressure model. First, human experiments have been designed and conducted, whereby measurements related to the model have been performed. Next, this data has been used to obtain appropriate parameter settings for the work pressure model, describing the specific subject. Finally, the work pressure model, with the tailored parameter settings, has been used to predict human behavior to investigate predictive capabilities of the model. The results have been analyzed using formal verification.
21. Hoogendoorn, M., Jaffry, S.W., and Treur, J., Parameter Estimation for Human Trust in Information Sources (Poster). Presented at Workshop on Parameter Estimation for Dynamical Systems (PEDS'09), Eindhoven, (The Netherlands), June 8th - 10th, 2009.
    • Title: "Parameter Estimation for Human Trust in Information Sources."
      Authors: Hoogendoorn, M., Jaffry, S.W., and Treur, J.,
      
      Abstract
      In this paper, an approach has been presented to learn parameters of a given trust model based upon observed experiences of a human. This approach has been introduced to enable a personal assistant agent to take such human trust into account when giving advice. Hereby, an existing trust model has been taken as a basis. Several methods have been used to enable learning of these parameters, including exhaustive search, Simulated Annealing, bisection, and an extended form of bisection. The process is adaptive in the sense that new experiences can come in, and are taking into consideration by finding the most appropriate parameter setting. The algorithms have been rigorously tested for various cases, and the results thereof have been analyzed using formal verification techniques. The results show that the computation time of the exhaustive search scales up worst, whereas the Simulated Annealing approach scales up best. When looking at the accuracy however, the inverse is true: exhaustive search finds the most accurate point, whereas Simulated Annealing sometimes only comes up with poor solutions. The bisection, and the more advanced extended bisection approach are right in the middle: They do have a higher accuracy and are computationally less expensive. The choice of which method to choose ultimately depends on the domain. For particular domains a higher computation time might be acceptable as long as the results are good, whereas in other more time critical domain speed could be a necessity. In this respect, the bisection approaches are a good combination of both worlds.
22. Bosse, T., Gerritsen, C., Hoogendoorn, M., Jaffry, S.W., and Treur, J., Agent-Based and Population-Based Simulation of Displacement of Crime (extended abstract). In: Ghallab, M. (ed.), Proceedings of the 18th European Conference on Artificial Intelligence, (ECAI'08), Patras, (Greece), July 21st - 25th, 2008. IOS Press, 2008, pp. 877-878. DOI (preliminary version)
    • Title: "Agent-Based and Population-Based Simulation of Displacement of Crime."
      Authors: Bosse, T., Gerritsen, C., Hoogendoorn, M., Jaffry, S.W., and Treur, J.
      
      Abstract
      Within Criminology, the process of crime displacement is usually explained by referring to the interaction of three types of agents: criminals, passers-by, and guardians. Most existing simulation models of this process are agent-based. However, when the number of agents considered becomes large, population-based simulation has computational advantages over agent-based simulation. This paper presents both an agent-based and a population-based simulation model of crime displacement, and reports a comparative evaluation of the two models. In addition, an approach is put forward to analyse the behaviour of both models by means of formal techniques.