Timothy Norman | University of Aberdeen (original) (raw)

Papers by Timothy Norman

In multi-agent systems, norms specify ideal behaviour. Agents, however, are autonomous, and may f... more In multi-agent systems, norms specify ideal behaviour. Agents, however, are autonomous, and may fail to comply with the ideal. Contrary to Duty obligations can be used to specify reparational behaviour that mitigates the effects of a violation. In addition to specifying reparational behaviours, it is important to understand how robust a system is against possible violations. Depending on what kind of system property we want to preserve, non-compliance with different norms may be of varying severity. We propose a method for analysing robustness of normative systems, with support for Contrary to Duty obligations. We introduce violation severity as a concept orthogonal to reparational behaviour and specify it by means of a partial order between norms. We use this severity partial order, together with normative specifications, to rank the possible worlds from the most to the least compliant. In this way, we are able to use model checking to analyse robustness to a certain severity, or whether it is possible to achieve a certain goal, without violating any norm of a given severity.

… agents and multiagent systems: part 1, Jan 1, 2002

Supervised interaction is concerned with the problem of establishing trust between contracting ag... more Supervised interaction is concerned with the problem of establishing trust between contracting agents in electronic markets. Agents act as representatives of their organisations or of individuals, negotiate contracts for the supply of goods and services and manage their delivery. It is essential for the automation of business transactions to put safeguards in place that ensure that errant behaviour is either prevented or sanctioned. The model proposed in the paper -Supervised Interaction -consists of three elements: an organisational framework, a contract specification language and a contract management protocol. The organisational framework emphasises the importance of introducing a trusted third party into any automated business transaction. Three essential roles are, therefore, proposed: the addressee, counter-party and authority. The normative positions of the agents involved in an automated business transaction are explicitly expressed within the contracts that govern agents' behaviour during supervised interaction. This interaction model is designed to provide the web of trust necessary for successful deployment of agent-mediated electronic markets.

Our focus is on the specification and verification of norma- tive systems that include contrary-t... more Our focus is on the specification and verification of norma- tive systems that include contrary-to-duty, collective and event-driven imperatives with deadlines. We propose an operational syntax and semantics for the specification of such systems. Using Maude and its model checker, we show how Linear Temporal Logic properties can be verified, and provide some experimental results.

D. Walton, A. Toniolo and T. J. Norman, Proceedings of the 11th International Workshop on Argumentation in Multi-Agent Systems, 2014.

In this paper, we introduce an extension to current leading models of deliberation dialogue to ca... more In this paper, we introduce an extension to current leading models of deliberation dialogue to capture dynamic changes of circumstances during an ongoing dialogue. Moreover, in natural deliberation, a dialogue may be successful even if a decision on what to do has not been made. A set of criteria is proposed to address the problem of when to close o the practical reasoning phase of dialogue.

Abstract: In modern coalition operations, decision makers must be capable of obtaining and fusing... more Abstract: In modern coalition operations, decision makers must be capable of obtaining and fusing information from diverse sources. The reliability of these sources can vary, and, to protect their interests, the information these sources provide could be altered, eg, obfuscated, to limit the inferences that can be made with it. The trustworthiness of fused information depends on both the reliability of these sources and their inference management policies.

ABSTRACT In this paper, we propose Ontological Logic Programming (OLP), a novel approach that com... more ABSTRACT In this paper, we propose Ontological Logic Programming (OLP), a novel approach that combines logic programming with ontological reasoning. The proposed approach enables the use of ontological terms (ie, individuals, classes and properties) directly within logic programs. The interpretation of these terms are delegated to an ontology reasoner during the interpretation of the program. Unlike similar approaches, OLP makes use of the full capacity of both the ontological reasoning and logic programming.

Coming up with a plan for a team that operates in a non-deterministic environment is a complex pr... more Coming up with a plan for a team that operates in a non-deterministic environment is a complex process, and the problem is further complicated by the need for team members to communicate while the plan is being executed. Such communication is required, for example, to make sure that information critical to the plan is passed in time for it to be useful. In this paper we present a model for constructing joint plans for a team of agents that takes into account their communication needs.

This paper describes work undertaken in the ADEPT (Advanced Decision Environment for Process Task... more This paper describes work undertaken in the ADEPT (Advanced Decision Environment for Process Tasks) project towards developing an agent-based infrastructure for managing business processes. We describe how the key technology of negotiating, service providing, autonomous agents was realised and demonstrate how this was applied to the BT business process of providing a customer quote for network services. Issues of agent visualisation are also addressed.

An important and non-trivial factor for effectively developing and resourcing plans in a collabor... more An important and non-trivial factor for effectively developing and resourcing plans in a collaborative context is an understanding of the policy and resource availability constraints under which others operate. We present an efficient approach for identifying, learning and modeling the policies of others during collaborative problem solving activities.

Abstract Development of innovative and effective technologies to support complex collaborative hu... more Abstract Development of innovative and effective technologies to support complex collaborative human activities depends both on observation and analysis of these activities and on iterative development and evaluation of the technologies in the deployment context. Applying these principles to military mission planning and execution is challenging. As a low cost approach to investigating these issues, we advocate the exploitation of commercial gaming environments.

Abstract Few existing argumentation frameworks are designed to deal with probabilistic knowledge,... more Abstract Few existing argumentation frameworks are designed to deal with probabilistic knowledge, and none are designed to represent possibilistic knowledge, making them unsuitable for many real world domains. In this paper we present a subjective logic based framework for argumentation which overcomes this limitation. Reasoning about the state of a literal in this framework can be done in polynomial time.

ABSTRACT A sensor network may be required to support multiple mission to be accomplished simultan... more ABSTRACT A sensor network may be required to support multiple mission to be accomplished simultaneously. Furthermore, the environment may change at any time; ie a new mission may arrive at any time. In solving this many-mission, manysensor problem in dynamic environments, conflicts between missions may occur for the use of sensor resources. A mechanism to match sensor resources to mission demands thus becomes necessary.

In this paper, we extend Dung's seminal argument framework to form a probabilistic argument frame... more In this paper, we extend Dung's seminal argument framework to form a probabilistic argument framework by associating probabilities with arguments and defeats. We then compute the likelihood of some set of arguments appearing within an arbitrary argument framework induced from this probabilistic framework.

Abstract In this paper, we describe how agents can support collaborative planning within internat... more Abstract In this paper, we describe how agents can support collaborative planning within international coalitions, formed in an ad hoc fashion as a response to military and humanitarian crises. As these coalitions are formed rapidly and without much lead time or co-training, human planners may be required to observe a plethora of policies that direct their planning effort.

Abstract. There are many significant contributions to the formal study of norm-governed organisat... more Abstract. There are many significant contributions to the formal study of norm-governed organisations. A key challenge in this endeavour is to provide designers and engineers with means to specify normative aspects of organisations, allowing phenomena such as norm conflict (ie, an action being simultaneously obliged and prohibited), to be captured and studied.

Abstract. An agent's behaviour is governed by multiple factors, including its beliefs/desires/int... more Abstract. An agent's behaviour is governed by multiple factors, including its beliefs/desires/intentions, its reasoning processes and societal influences acting upon it, such as norms. In this paper we propose an extensible argumentation inspired reasoning procedure, and show how it may be used to perform normative reasoning.. The language used by our procedure is built around defeasible, nonmonotonic rules called argument schemes.

Abstract The emergence of large scale, distributed, sensor-enabled, machine-to-machine pervasive ... more Abstract The emergence of large scale, distributed, sensor-enabled, machine-to-machine pervasive applications necessitates engaging with providers of information on demand to collect the information, of varying quality levels, to be used to infer about the state of the world and decide actions in response.

Agents may choose to ignore contract violations if the costs of enforcing the contract exceed the... more Agents may choose to ignore contract violations if the costs of enforcing the contract exceed the compensation they would receive. In this paper we describe an argumentation based framework for agents to both decide whether to enforce a contract, and to undertake contract enforcement actions. The framework centres around agents presenting beliefs to justify their position, and backing up these beliefs with facts as necessary.

Abstract—Sensing resources play a crucial role in the success of critical tasks such as surveilla... more Abstract—Sensing resources play a crucial role in the success of critical tasks such as surveillance. Therefore, it is important to assigning appropriate sensing resources to tasks such that the selected resources fully cater the needs of the tasks. However, selecting the right resources to tasks is a computationally hard problem to solve.

In multi-agent systems, norms specify ideal behaviour. Agents, however, are autonomous, and may f... more In multi-agent systems, norms specify ideal behaviour. Agents, however, are autonomous, and may fail to comply with the ideal. Contrary to Duty obligations can be used to specify reparational behaviour that mitigates the effects of a violation. In addition to specifying reparational behaviours, it is important to understand how robust a system is against possible violations. Depending on what kind of system property we want to preserve, non-compliance with different norms may be of varying severity. We propose a method for analysing robustness of normative systems, with support for Contrary to Duty obligations. We introduce violation severity as a concept orthogonal to reparational behaviour and specify it by means of a partial order between norms. We use this severity partial order, together with normative specifications, to rank the possible worlds from the most to the least compliant. In this way, we are able to use model checking to analyse robustness to a certain severity, or whether it is possible to achieve a certain goal, without violating any norm of a given severity.

… agents and multiagent systems: part 1, Jan 1, 2002

Supervised interaction is concerned with the problem of establishing trust between contracting ag... more Supervised interaction is concerned with the problem of establishing trust between contracting agents in electronic markets. Agents act as representatives of their organisations or of individuals, negotiate contracts for the supply of goods and services and manage their delivery. It is essential for the automation of business transactions to put safeguards in place that ensure that errant behaviour is either prevented or sanctioned. The model proposed in the paper -Supervised Interaction -consists of three elements: an organisational framework, a contract specification language and a contract management protocol. The organisational framework emphasises the importance of introducing a trusted third party into any automated business transaction. Three essential roles are, therefore, proposed: the addressee, counter-party and authority. The normative positions of the agents involved in an automated business transaction are explicitly expressed within the contracts that govern agents' behaviour during supervised interaction. This interaction model is designed to provide the web of trust necessary for successful deployment of agent-mediated electronic markets.

Our focus is on the specification and verification of norma- tive systems that include contrary-t... more Our focus is on the specification and verification of norma- tive systems that include contrary-to-duty, collective and event-driven imperatives with deadlines. We propose an operational syntax and semantics for the specification of such systems. Using Maude and its model checker, we show how Linear Temporal Logic properties can be verified, and provide some experimental results.

D. Walton, A. Toniolo and T. J. Norman, Proceedings of the 11th International Workshop on Argumentation in Multi-Agent Systems, 2014.

In this paper, we introduce an extension to current leading models of deliberation dialogue to ca... more In this paper, we introduce an extension to current leading models of deliberation dialogue to capture dynamic changes of circumstances during an ongoing dialogue. Moreover, in natural deliberation, a dialogue may be successful even if a decision on what to do has not been made. A set of criteria is proposed to address the problem of when to close o the practical reasoning phase of dialogue.

Abstract: In modern coalition operations, decision makers must be capable of obtaining and fusing... more Abstract: In modern coalition operations, decision makers must be capable of obtaining and fusing information from diverse sources. The reliability of these sources can vary, and, to protect their interests, the information these sources provide could be altered, eg, obfuscated, to limit the inferences that can be made with it. The trustworthiness of fused information depends on both the reliability of these sources and their inference management policies.

ABSTRACT In this paper, we propose Ontological Logic Programming (OLP), a novel approach that com... more ABSTRACT In this paper, we propose Ontological Logic Programming (OLP), a novel approach that combines logic programming with ontological reasoning. The proposed approach enables the use of ontological terms (ie, individuals, classes and properties) directly within logic programs. The interpretation of these terms are delegated to an ontology reasoner during the interpretation of the program. Unlike similar approaches, OLP makes use of the full capacity of both the ontological reasoning and logic programming.

Coming up with a plan for a team that operates in a non-deterministic environment is a complex pr... more Coming up with a plan for a team that operates in a non-deterministic environment is a complex process, and the problem is further complicated by the need for team members to communicate while the plan is being executed. Such communication is required, for example, to make sure that information critical to the plan is passed in time for it to be useful. In this paper we present a model for constructing joint plans for a team of agents that takes into account their communication needs.

This paper describes work undertaken in the ADEPT (Advanced Decision Environment for Process Task... more This paper describes work undertaken in the ADEPT (Advanced Decision Environment for Process Tasks) project towards developing an agent-based infrastructure for managing business processes. We describe how the key technology of negotiating, service providing, autonomous agents was realised and demonstrate how this was applied to the BT business process of providing a customer quote for network services. Issues of agent visualisation are also addressed.

An important and non-trivial factor for effectively developing and resourcing plans in a collabor... more An important and non-trivial factor for effectively developing and resourcing plans in a collaborative context is an understanding of the policy and resource availability constraints under which others operate. We present an efficient approach for identifying, learning and modeling the policies of others during collaborative problem solving activities.

Abstract Development of innovative and effective technologies to support complex collaborative hu... more Abstract Development of innovative and effective technologies to support complex collaborative human activities depends both on observation and analysis of these activities and on iterative development and evaluation of the technologies in the deployment context. Applying these principles to military mission planning and execution is challenging. As a low cost approach to investigating these issues, we advocate the exploitation of commercial gaming environments.

Abstract Few existing argumentation frameworks are designed to deal with probabilistic knowledge,... more Abstract Few existing argumentation frameworks are designed to deal with probabilistic knowledge, and none are designed to represent possibilistic knowledge, making them unsuitable for many real world domains. In this paper we present a subjective logic based framework for argumentation which overcomes this limitation. Reasoning about the state of a literal in this framework can be done in polynomial time.

ABSTRACT A sensor network may be required to support multiple mission to be accomplished simultan... more ABSTRACT A sensor network may be required to support multiple mission to be accomplished simultaneously. Furthermore, the environment may change at any time; ie a new mission may arrive at any time. In solving this many-mission, manysensor problem in dynamic environments, conflicts between missions may occur for the use of sensor resources. A mechanism to match sensor resources to mission demands thus becomes necessary.

In this paper, we extend Dung's seminal argument framework to form a probabilistic argument frame... more In this paper, we extend Dung's seminal argument framework to form a probabilistic argument framework by associating probabilities with arguments and defeats. We then compute the likelihood of some set of arguments appearing within an arbitrary argument framework induced from this probabilistic framework.

Abstract In this paper, we describe how agents can support collaborative planning within internat... more Abstract In this paper, we describe how agents can support collaborative planning within international coalitions, formed in an ad hoc fashion as a response to military and humanitarian crises. As these coalitions are formed rapidly and without much lead time or co-training, human planners may be required to observe a plethora of policies that direct their planning effort.

Abstract. There are many significant contributions to the formal study of norm-governed organisat... more Abstract. There are many significant contributions to the formal study of norm-governed organisations. A key challenge in this endeavour is to provide designers and engineers with means to specify normative aspects of organisations, allowing phenomena such as norm conflict (ie, an action being simultaneously obliged and prohibited), to be captured and studied.

Abstract. An agent's behaviour is governed by multiple factors, including its beliefs/desires/int... more Abstract. An agent's behaviour is governed by multiple factors, including its beliefs/desires/intentions, its reasoning processes and societal influences acting upon it, such as norms. In this paper we propose an extensible argumentation inspired reasoning procedure, and show how it may be used to perform normative reasoning.. The language used by our procedure is built around defeasible, nonmonotonic rules called argument schemes.

Abstract The emergence of large scale, distributed, sensor-enabled, machine-to-machine pervasive ... more Abstract The emergence of large scale, distributed, sensor-enabled, machine-to-machine pervasive applications necessitates engaging with providers of information on demand to collect the information, of varying quality levels, to be used to infer about the state of the world and decide actions in response.

Agents may choose to ignore contract violations if the costs of enforcing the contract exceed the... more Agents may choose to ignore contract violations if the costs of enforcing the contract exceed the compensation they would receive. In this paper we describe an argumentation based framework for agents to both decide whether to enforce a contract, and to undertake contract enforcement actions. The framework centres around agents presenting beliefs to justify their position, and backing up these beliefs with facts as necessary.

Abstract—Sensing resources play a crucial role in the success of critical tasks such as surveilla... more Abstract—Sensing resources play a crucial role in the success of critical tasks such as surveillance. Therefore, it is important to assigning appropriate sensing resources to tasks such that the selected resources fully cater the needs of the tasks. However, selecting the right resources to tasks is a computationally hard problem to solve.