Sofia Panagiotidi

Towards a Formalisation of Electronic Contracting Environments

Clauses within contracts may be thought of as norms, specifying permissions, obligations and prohibitions on contract parties. In this paper, we present a formal representation of contracts, focusing on the specification of a model of norms. With this model, a norm is associated with a status, which may change as the environment, and the status of other norms, changes. We define a normative environment, which may be used to track the status of a set of norms throughout their lifecycle, and then describe a predicates that may be used to evaluate a norms status. Agents are able to use these predicates to reason about the status of norms, and how their actions will affect the normative environment. Finally, we show the applicability of our framework to real world domains by monitoring the execution of a contract taken from a real world scenario.

Reasoning over norm compliance via planning

Norms are a way to provide some flexibility to the specification of acceptable actor behaviour in a shared context. Instead of viewing norms as static restrictions over an agents conduct (and autonomy), the full power of normative specifications comes when norms are seen as guidelines that agents can use in their decision-making. In literature there is a lot of work on norm theories, models and specifications on how agents might take norms into account when reasoning, but many of them focus on the goal or intention selection and few of them apply the norms into the agents plan generation. In this paper we present a norm-oriented agent that takes into consideration operationalised norms during the plan generation phase, using them as guidelines to decide the agents future action path. In our work norms can be obligations or prohibitions which can be violated, and are accompanied by repair norms in case they are breached. To make norms influence plan generation, our norm operational semantics is expressed as an extension/on top of STRIPS semantics, acting as a form of temporal restrictions over the trajectories (plans) computed by the planner. In combination with the agents utility functions over the actions, the norm-aware planner computes the most profitable trajectory concluding to a state of the world where the effects of all the active norms have been explored, including the repair norms. We use a simplified fire emergency scenario in order to demonstrate the usefulness of the framework, integrating the norm-aware planner to 2APL agent architecture. We depict possible outcomes depending on criteria such as time and danger.

Norm-Aware Planning: Semantics and Implementation

Norms are a way to specify acceptable behaviour in a context. In literature there is a lot of work on norm theories, models and specifications on how agents might take norms into account when reasoning but few practical implementations. In this paper we present a framework and an implementation for norm-oriented planning. Unlike most frameworks, our approach takes into consideration the operationalisation of norms during the plan generation phase. In our framework norms can be obligations or prohibitions which can be violated, and are accompanied by repair norms in case they are breached. Norm operational semantics is expressed as an extension/on top of STRIPS semantics, acting as a form of temporal restrictions over the trajectories (plans) computed by the planner. In combination with the agents utility functions over the actions, the norm-aware planner computes the most profitable trajectory concluding to a state of the world where no pending obligations exist and any (obligation/prohibition) violation has been handled. An implementation of the framework in PDDL is provided.

Towards practical normative agents: a framework and an implementation for norm-aware planning

Nowadays there is an important increase in the adoption and use of distributed computational solutions which are growing both in size (from tens to hundreds or even thousands of components, computational entities or actors) and in complexity (from closed, static, pre-defined interactions to more open, dynamic ones stablished at run-time). In this scenario one way to tame such complexity is to add a social layer on top regulating or shaping the behaviour of the actors in the system. One of those social abstractions that has been explored in literature is the use of computational models of (social or organisational) norms. Most of these approaches see norms as a way to specify acceptable agent behaviour in some (distributed) context. In literature there is a lot of work on norm theories, models and specifications on how agents might take norms into account when reasoning but few practical implementations. In this paper we present a first step into the implementation of practical normative agents by describing a framework and an implementation of norm-oriented planning. In this framework norms can be either obligations or prohibitions which can be violated, and are accompanied by repair norms in case they are breached. Unlike most frameworks, our approach takes into consideration the operationalisation of norms during the plan generation phase. Norm operational semantics is expressed as an extension/on top of STRIPS semantics, acting as a form of temporal restrictions over the trajectories (plans) computed by the planner. In combination with the agents utility functions over the actions, the norm-aware planner computes the most profitable trajectory concluding to a state of the world where no pending obligations exist and any (obligation/prohibition) violation has been handled. An implementation of the framework in PDDL is described.

Contextual Norm-Based Plan Evaluation via Answer Set Programming

There is a recent trend on agent-oriented methods and abstractions in the field of Service Engineering to tackle governance of distributed (Semantic) Web systems. Some approaches are based on the creation of a social level where actors’ behaviour is regulated by means of computational norms. We present a framework where norm-enabled agents can, at runtime, 1) enter an organisational context, 2) get the organisational specification, including norms, and translate it into the agents’ internal representation and 3) determine the quality of a to-be-adopted plan taking into account the incentives derived from the norm-regulated context. A normative model formalisation is provided using Semantic Web elements. Then a translation of the formalism into Answer Set Programming and a full implementation of a normative plan evaluator are presented.

Socially-Aware emergent narrative

In agent research, emergent narrative aims for practical solutions to the narrative paradox problem in both drama and interactive scenarios. At the same time, organisational frameworks can be used in games to provide flexibility, adaptiveness, or social-awareness. In this paper, we propose an extension of our cOncienS framework to support emergent narrative in games with two objectives: 1) provide social-awareness in emergent narrative by means of an organisational model, and 2) create convincing dynamic and flexible storytelling in games.

A middleware architecture for building contract-aware agent-based services

This paper presents a middleware to help designers in theimplementation of contract-aware agent-based services. The middlewareprovides several components, including a contract manager, a communicationmanager and a workflow manager, which combine to allow agentsto manage contracts and the actions associated with them. The middlewareis built as part of a Web service implementation of the ISTCONTRACTframework. An electronic commerce example is used toillustrate how the components of the middleware facilitates the managementand execution of agreements in a contract at run-time.