www.governatori.net

Publications on Deontic Logic and Normative Reasoning

Grigoris Antoniou, David Billington, Guido Governatori, and Michael J. Maher.

On the modeling and analysis of regulations. In Proceedings of the Australian Conference Information Systems, pages 20-29, 1999.
Abstract:Regulations are a wide-spread and important part of government and business. They codify how products must be made and processes should be performed. Such regulations can be difficult to understand and apply. In an environment of growing complexity of, and change in, regulation, automated support for reasoning with regulations is becoming increasingly necessary. In this paper we report on ongoing work which aims at providing automated support for the drafting and use of regulations using logic modelling techniques. We highlight the support that can be provided by logic modelling, describe the technical foundation of our project, and report on the status of the project and the next steps.
 

Grigoris Antoniou, Nikos Dimaresis, and Guido Governatori.

A system for modal and deontic defeasible reasoning. In Mehmet A. Orgun and John Thornton, editors, 20th Australian Joint Conference on Artificial Intelligence, AI 2007, LNAI 4830, pages 609-613. Springer, 2007. Copyrigth © 2007 Springer.
Abstract: Defeasible reasoning is a well-established nonmonotonic reasoning approach that has recently been combined with semantic web technologies. This paper describes modal and deontic extensions of defeasible logic, motivated by potential applications for modelling multi-agent systems and policies. It describes a logic metaprogram that captures the underlying intuitions, and outlines an implemented system.
 

Alberto Artosi, Paola Cattabriga, and Guido Governatori.

An automated approach to normative reasoning. In Joost Breuker, editor, Artificial Normative Reasoning, pages 132-145, Amsterdam, 1994. ECAI'94.
 

Alberto Artosi, Paola Cattabriga, and Guido Governatori.

KED: A deontic theorem prover. In Carlo Biagioli, Giovanni Sartor, and Daniela Tiscornia, editors, Workshop on Legal Application of Logic Programming, pages 60-76, Firenze, 1994. ICLP'94, IDG.
 

Alberto Artosi and Guido Governatori.

A tableaux methodology for deontic conditional logics. In ΔEON'98, 4^th International Workshop on Deontic Logic in Computer Science, pages 65-81, Bologna, 1998. CIRFID.
Abstract:In this paper we present a theorem proving methodology for a restricted but significant fragment of the conditional language made up of (boolean combinations of) conditional statements with unnested antecedents. The method is based on the possible world semantics for conditional logics. The label formalism introduced in \cite{cade,jelia} to account for the semantics of normal modal logics is easily adapted to the semantics of conditional logics by simply indexing labels with formulas. The inference rules are provided by the propositional system KE⁺ - a tableau-like analytic proof system devised to be used both as a refutation and a direct method of proof - enlarged with suitable elimination rules for the conditional connective. The theorem proving methodology we are going to present can be viewed as a first step towards developing an appropriate algorithmic framework for several conditional logics for (defeasible) conditional obligation.
 

Alberto Artosi, Guido Governatori, and Giovanni Sartor.

Towards a computational treatment of deontic defeasibility. In Mark Brown and José Carmo, editors, Deontic Logic Agency and Normative Systems, Workshop on Computing, pages 27-46, Berlin, 1996. Springer-Verlag, Copyrigth © 1996 Springer-Verlag.
Abstract:In this paper we describe an algorithmic framework for a multi-modal logic arising from the combination of the system of modal (epistemic) logic devised by Meyer and van der Hoek for dealing with nonmonotonic reasoning with a deontic logic of the Jones and Pörn-type. The idea behind this (somewhat eclectic) formal set-up is to have a modal framework expressive enough to model certain kinds of deontic defeasibility, in particular by taking into account preferences on norms. The appropriate inference mechanism is provided by a tableau-like modal theorem proving system which supports a proof method closely related to the semantics of modal operators. We argue that this system is particularly well-suited for mechanizing nonmonotonic forms of inference in a monotonic multi-modal setting.
 

Dov M. Gabbay and Guido Governatori.

Dealing with label dependent deontic modalities. In Paul McNamara and Henry Prakken, editors, Norms, Logics and Information Systems. New Studies in Deontic Logic, pages 311-330. IOS Press, Amsterdam, 1998.
Abstract:In this paper, following Scott's advice, we argue that normative reasoning can be represented in a multi-setting framework; in particular in a multi-modal one, where modalities are indexed. Indexed modalities can model several aspects involved in normative reasoning. Systems are combined using Gabbay's fibring methodology which provides complete semantics that can be used to model a labelled tableau-like proofs system.
 

Jonathan Gelati, Guido Governatori, Antonino Rotolo, and Giovanni Sartor.

Declarative power, representation, and mandate: A formal anaysis. In Trevor Bench-Capon, Aspassia Daskalopulu, and Radboudb Winkels, editors, Legal Knowledge and Information Systems, number 89 in Frontieres in Artificial Intelligence and Applications, pages 41-52. IOS Press, Amsterdam, 2002.
Abstract:In this paper we provide a formal framework for developing the idea of normative co-ordination. We argue that this idea is based on the assumption that agents can achieve flexible co-ordination by conferring normative positions to other agents. These positions include duties, permissions, and powers. In particular, we introduce the idea of declarative power, which consists in the capacity of the power-holder of creating normative positions, involving other agents, simply by ``proclaiming'' such positions. In addition, we account also for the concepts of representation, consisting in the representative's capacity of acting in the name of his principal, and of mandate, which corresponds the mandatee's duty to act as the mandator has requested. Finally, we show how the above framework can be applied to the contract-net protocol.
 

Jonathan Gelati, Guido Governatori, Antonino Rotolo, and Giovanni Sartor.

Normative autonomy and normative co-ordination: Declarative power, representation, and mandate. Artificial Intelligence and Law, 12 (1-2), 53-81. 2004. Copyright © 2004 Springer. The original publication is available at www.springerlink.com
Abstract:In this paper we provide a formal analysis of the idea of normative co-ordination. We argue that this idea is based on the assumption that agents can achieve flexible co-ordination by conferring normative positions to other agents. These positions include duties, permissions, and powers. In particular, we explain the idea of declarative power, which consists in the capacity of the power-holder of creating normative positions, involving other agents, simply by ``proclaiming'' such positions. In addition, we account also for the concepts of representation, namely the representative's capacity of acting in the name of his principal, and of mandate, which is the mandatee's duty to act as the mandator has requested. Finally, we show how the framework can be applied to represent the contract-net protocol. Some brief remarks on future research and applications conclude this contribution.
 

Guido Governatori.

Un modello formale per il ragionamento giuridico. PhD thesis, CIRFID, University of Bologna, Bologna, 1997.
 

Guido Governatori.

Ideality and subideality from a computational point of view. In Alberto Artosi, Manuel Atienza, and Hajme Yoshino, editors, From Practical Reason to Legal Computer Science. Legal Computer Science, volume Part II, pages 315-329. Clueb, Bologna, 1998.
Abstract:In this paper we suggest ways in which logic and law may usefully relate; and we present an analytic proof system dealing with the Jones Pörn's deontic logic of Ideality and Subideality, which offers some suggestions about how to embed legal systems in label formalism.
 

Guido Governatori.

Defeasible description logic. In Grigoris Antoniou and Harold Boley, editors, Rules and Rule Markup Languages for the Semantic Web: Third International Workshop, RuleML 2004, number 3323 in LNCS, pages 98-112, Berlin, 8 November 2004. Springer-Verlag Copyright © 2004, Springer. The original pubblication is available at www.springerlink.com
Abstract:We propose to extend description logic with defeasible rules, and to use the inferential mechanism of defeasible logic to reason with description logic constructors.
 

Guido Governatori.

Representing business contracts in {RuleML}. International Journal of Cooperative Information Systems, 14 no. 2-3, June-September 2005.
Abstract:This paper presents an approach for the specification and implementation of translating contracts from a human-oriented form into an executable representation for monitoring. This will be done in the setting of \RuleML. The task of monitoring contract execution and performance requires a logical account of deontic and defeasible aspects of legal language; currently such aspects are not covered by \RuleML; accordingly we show how to extend it to cover such notions. From its logical form, the contract will be thus transformed into a machine readable rule notation and eventually implemented as executable semantics via any mark-up languages depending on the client's preference, for contract monitoring purposes.
 

Guido Governatori, Marlon Dumas, Arthur H.M. ter Hofstede, and Phillipa Oaks.

A formal approach to protocols and strategies for (legal) negotiation. In Henry Prakken, editor, Procedings of the 8th International Conference on Artificial Intelligence and Law, pages 168-177. IAAIL, ACM Press, 2001, Copyrigth © 2001 ACM.
Abstract:We propose a formal and executable framework for expressing protocols and strategies for automated (legal) negotiation. In this framework a party involved in a negotiation is represented through a software agent composed of four modules: (i) a communication module which manages the interaction with the other agents; (ii) a control module; (iii) a reasoning module specified as a defeasible theory; and (iv) a knowledge base which bridges the control and the reasoning modules, while keeping track of past decisions and interactions. The choice of defeasible logic is justified against a set of desirable criteria for negotiation automation languages. Moreover, the suitability of the framework is illustrated through two case studies.
 

Guido Governatori, Jonathan Gelati, Antonino Rotolo, and Giovanni Sartor.

Actions, institutions, powers. preliminary notes. In Gabriela Lindemann, Daniel Moldt, Mario Paolucci, and Bin Yu, editors, International Workshop on Regulated Agent-Based Social Systems: Theories and Applications (RASTA'02), volume 318 of Mitteilung, pages 131-147, 2002. Fachbereich Informatik, Universität Hamburg.
Abstract:In this paper we analyse some logical notions relevant for representing the dynamics of institutionalised organisations. In particular, some well-known action concepts introduced in the Kanger-Lindahl-Pörn logical theory of agency are discussed and integrated. Secondly, moving from the work of Jones and Sergot, a logical characterisation is provided of the ideas of institutional links, ``counts-as'' connections, and institutional facts. This approach is then enriched by a new modal operator $\mathit{proc}$, intended to account for the autonomous and decentralised creation of new institutional facts and normative positions within institutions.
 

Guido Governatori, Jörg Hoffmann, Shazia Sadiq, and Ingo Weber.

Detecting regulatory compliance for business process models through semantic annotations. In 4th International Workshop on Business Process Design, Milan, 1 September 2008 2008.
Abstract: A given business process may face a large number of regulatory obligations the process may or comply with. Providing tools and techniques through which an evaluation of the compliance degree of a given process can be undertaken is seen as a key objective in emerging business process platforms. We address this problem through a diagnostic framework that provides the ability to assess the compliance gaps present in a given process. Checking whether a process is compliant with the rules involves enumerating all reachable states and is hence, in general, a hard search problem. The approach taken here allows to provide useful diagnostic information in polynomial time. The approach is based on two underlying techniques. A conceptually faithful representation for regulatory obligations is firstly provided by a formal rule language based on a non-monotonic deontic logic of violations. Secondly, processes are formalized through semantic annotations that allow a logical state space to be created. The intersection of the two allows us to devise an efficient method to detect compliance gaps; the method guarantees to detect all obligations that will necessarily arise during execution, but that will not necessarily be fulfilled.
 

Guido Governatori, Joris Hulstijn, Règis Riveret, and Antonino Rotolo.

On the representation of deadlines in a rental agreement. In Arno R. Lodder and Laurens Mommers, editors, Legal Knowledge and Information Systems, pages 167-168. IOS Press, Amsterdam, 2007.
Abstract: The paper provides a conceptual analysis of deadlines, represented in Temporal Modal Defeasible Logic. The typology is based on the following parameters: kind of deontic operator, maintenance or achievement, presence of explicit sanctions, and persistence after the deadline. The adequacy of the typology is validated against a case study of a rental agreement.
 

Guido Governatori, Joris Hulstijn, Régis Riveret, and Antonino Rotolo.

Characterising deadlines in temporal modal defeasible logic. In Mehmet A. Orgun and John Thornton, editors, 20th Australian Joint Conference on Artificial Intelligence, AI 2007, LNAI 4830, pages 486-496. Springer, 2007. Copyrigth © 2007 Springer.
Abstract: We provide a conceptual analysis of several kinds of deadlines, represented in Temporal Modal Defeasible Logic. The paper presents a typology of deadlines, based on the following parameters: deontic operator, maintenance or achievement, presence or absence of sanctions, and persistence after the deadline. The deadline types are illustrated by a set of examples.
 

Guido Governatori, Alessio Lomuscio, and Marek Sergot.

A tableaux system for deontic interpreted systems. In Tamás D. Gedeon and Lance Chun Che Fung, editors, AI 2003: Advances in Artificial Intelligence, volume 2903 of LNAI, pages 339-351, Springer-Verlag, Berlin, 2003. Copyrigth © 2003 Springer-Verlag.
Abstract:We develop a labelled tableaux system for the modal logic $KD45^i-j_n$ extended with epistemic notions. This logic characterises a particular type of interpreted systems used to represent and reason about states of correct and incorrect functioning behaviour of the agents in a system, and of the system as a whole. The resulting tableaux system provides a simple decision procedure for the logic. We discuss these issues and we illustrate them with the help of simple examples.
 

Guido Governatori and Zoran Milosevic.

Dealing with contract violations: formalism and domain specific language. Proceedings of EDOC 2005. IEEE Press, 2005, pp. 46-57. Copyrigth © 2005 IEEE.
Abstract:This paper presents a formal system for reasoning about violations of obligations in contracts. The system is based on the formalism for the representation of contrary-to-duty obligations. These are the obligations that take place when other obligations are violated as typically applied to penalties in contracts. The paper shows how this formalism can be mapped onto the key policy concepts of a contract specification language. This language, called Business Contract Language (BCL) was previously developed to express contract conditions of relevance for run time contract monitoring. The aim of this mapping is to establish a formal underpinning for this key subset of BCL.
 

Guido Governatori, and Zoran Milosevic

An Approach for Validating BCL Contract Specifications In Claudio Bartolini, Guido Governatori, and Zoran Milosevic (eds). Proceedings on the 2nd EDOC Workshop on Contract Architecures and Languages (CoALa 2005). Enschede, NL, 20 September 2005. IEEE Press.
Abstract:We continue the study, started in [5], on the formal relationships between a domain specific contract language (BCL) and the logic of violation (FCL) proposed in [6,7]. We discuss the use of logical methods for the representation and analysis of business contracts. The proposed analysis is based on the notions of normal and canonical forms of contracts expressed in FCL. Finally we present a mapping from FCL to BCL that can be used to provide an executable model of a formal representation of a contract.
 

Guido Governatori and Zoran Milosevic.

A Formal Analysis of a Business Contract Language. International Journal of Cooperative Information Systems 15, in print. Copyrigth © 2006 World Scientific Press.
Abstract: This paper presents a formal system for reasoning about violations of obligations in contracts. The system is based on the formalism for the representation of contrary-to-duty obligations. These are the obligations that take place when other obligations are violated as typically applied to penalties in contracts. The paper shows how this formalism can be mapped onto the key policy concepts of a contract specification language, called Business Contract Language (BCL), previously developed to express contract conditions for run time contract monitoring. The aim of this mapping is to establish a formal underpinning for this key subset of BCL.
 

Guido Governatori, Zoran Milosevic, and Sahzia Sadiq

Compliance checking between business processes and business contracts 10th International Enterprise Distributed Object Computing Conference (EDOC 2006). IEEE Press, 2006, pp. 221-232. Copyrigth © 2006 IEEE.
Abstract: It is a typical scenario that many organisations have their business processes specified independently of their business contracts. This is because of the lack of guidelines and tools that facilitate derivation of processes from contracts but also because of the traditional mindset of treating contracts separately from business processes. This paper provides a solution to one specific problem that arises from this situation, namely the lack of mechanisms to check whether business processes are compliant with business contracts. The central part of the paper are logic based formalism for describing both the semantics of contract and the semantics of compliance checking procedures.
 

Guido Governatori, Vineet Padmanabhan, Antonino Rotolo, and Abdul Sattar.

A defeasible logic for modelling policy-based intentions and motivational attitudes. Logic Journal of the IGPL, 17(3), 2009. Copyrigth © 2009 Oxford University Press.
Abstract: In this paper we show how defeasible logic could formally account for the non-monotonic properties involved in motivational attitudes like intention and obligation. Usually, normal modal operators are used to represent such attitudes wherein classical logical consequence and the rule of necessitation comes into play i.e., $\vdash A / \vdash \Box A$, that is from $\vdash A$ derive $\vdash\Box A$. This means that such formalisms are affected by the Logical Omniscience problem. We show that policy-based intentions exhibit non-monotonic behaviour which could be captured through a non-monotonic system like defeasible logic. To this end we outline a defeasible logic of intention that specifies how modalities can be introduced and manipulated in a non-monotonic setting without giving rise to the problem of logical omniscience. In a similar way we show how to add deontic modalities defeasibly and how to integrate them with other motivational attitudes like beliefs and goals. Finally we show that the basic aspect of the BOID architecture is captured by this extended framework.
 

Guido Governatori, Monica Palmirani, Régis Riveret, Antonino Rotolo and Giovanni Sartor.

Normative Modifications in Defeasible Logic. In Marie-Francine Moens, editor, Jurix'05: The Eighteenth Annual Conference, in print. IOS Press, Amsterdam 2005.
Abstract: This paper proposes a framework based on Defeasible Logic (DL) to reason about normative modifications. We show how to express them in DL and how the logic deals with conflicts between temporalised normative modifications. Some comments will be given with regard to the phenomenon of retroactivity.
 

Guido Governatori, and Duy Pham Hoang

DR-CONTRACT: An Architecture for e-Contracts in Defeasible Logic In Claudio Bartolini, Guido Governatori, and Zoran Milosevic (eds). Proceedings on the 2nd EDOC Workshop on Contract Architecures and Languages (CoALa 2005). Enschede, NL, 20 September 2005. IEEE Press.
Abstract:In this paper we present an architecture to represent and reason on e-Contracts based on the DR-device architecture supplemented with a deontic defeasible logic of violation. We motivate the choice for the logic and we show how to extend RuleML to capture the notions relevant to describe e-contracts for a monitoring perspective in Defeasible Logic.
 

Guido Governatori and Duy Hoang Pham

A Semantic Web Based Architecture for e-Contracts in Defeasible Logic. In A. Adi, S. Stoutenberg and S. Tabet, editors, Rules and Rule Markup Languages for the Semantic Web. RuleML 2005, pages 145-159. LNCS 3791, Springer, Berlin, 2005. The original pubblication is available at www.springerlink.com.
Abstract: We introduce the DR-CONTRACT architecture to represent and reason on e-Contracts. The architecture extends the DR-device architecture by a deontic defeasible logic of violation. We motivate the choice for the logic and we show how to extend \RuleML to capture the notions relevant to describe e-contracts for a monitoring perspective in Defeasible Logic.
 

Guido Governatori and Duy Hoang Pham.

DR-CONTRACT: An Architecture for e-Contracts in Defeasible Logic. International Journal of Business Process Integration and Management, 5(4), 2009.
Abstract: We introduce the DR-CONTRACT architecture to represent and reason on e-Contracts. The architecture extends the DR-device architecture by a deontic defeasible logic of violation. We motivate the choice for the logic and we show how to extend RuleML to capture the notions relevant to describe e-contracts for a monitoring perspective in Defeasible Logic.
 

Guido Governatori and Antonino Rotolo.

Logic of Violations: A Gentzen System for Reasoning with Contrary-To-Duty Obligations Australasian Journal of Logic 4: 193-215, 2006.
Abstract: In this paper we present a Gentzen system for reasoning with contrary-to-duty obligations. The intuition behind the system is that a contrary-to-duty is a special kind of normative exception. The logical machinery to formalise this idea is taken from substructural logics and it is based on the definition of a new non-classical connective capturing the notion of reparational obligation. Then the system is tested against well-known contrary-to-duty paradoxes.
 

Guido Governatori and Antonino Rotolo.

A Gentzen system for reasoning with contrary-to-duty obligations. a preliminary study. In Andrew J.I. Jones and John Horty, editors, Δeon'02, pages 97-116, London, May 2002. Imperial College.
Abstract:In this paper we present a Gentzen system for reasoning with contrary-to-duty obligations. The intuition behind the system is that a contrary-to-duty is a special kind of normative exception. The logical machinery to formalize this idea is taken from substructural logics and it is based on the definition of a new non-classical connective capturing the notion of reparational obligation. Then the system is tested against well-known contrary-to-duty paradoxes.
 

Guido Governatori and Antonino Rotolo.

A computational framework for non-monotonic agency, institutionalised power and multi-agent systems. In Daniéle Bourcier, editor, Legal Knowledge and Inforamtion Systems, volume 106 of Frontieres in Artificial Intelligence and Applications, pages 151-152, IOS Press, Amsterdam, 2003.
 

Guido Governatori and Antonino Rotolo.

Defeasible logic: Agency and obligation. In Alessio Lomuscio and Donald Nute, editors, Deontic Logic in Computer Science, number 3065 in LNAI, pages 114-128, Springer-Verlag, Berlin, 2004. Copyrigth © 2004 Spinger.
Abstract:We propose a computationally oriented non-monotonic multi-modal logic arising from the combination of agency, intention and obligation. We argue about the defeasible nature of these notions and then we show how to represent and reason with them in the setting of defeasible logic.
 

Guido Governatori and Antonino Rotolo.

Representing contracts using RuleML. In Thomas Gordon, editor, Legal Knowledge and Information Systems, volume 120 of Frontieres in Artificial Intelligence and Applications, pages 141-150, Amsterdam, 2004. IOS Press.
Abstract:This paper presents an approach for the specification and implementation of e-contracts for Web monitoring. This is done in the setting of RuleML. We argue that monitoring contract execution requires also a logical account of deontic concepts and of violations. Accordingly, RuleML is extended to cover these aspects.
 

Guido Governatori and Antonino Rotolo.

A computational framework for institutional agency. Artificial Intelligence and Law, 16 no. 1 pp. 25-52, 2008., Copyrigth © 2008 Springer.
Abstract: This paper provides a computational framework, based on Defeasible Logic, to capture some aspects of institutional agency. Our background is Kanger-Lindahl-Pörn account of organised interaction, which describes this interaction within a multi-modal logical setting. This work focuses in particular on the notions of counts-as link and on those of attempt and of personal and direct action to realise states of affairs. We show how standard Defeasible Logic can be extended to represent these concepts: the resulting system preserves some basic properties commonly attributed to them. In addition, the framework enjoys nice computational properties, as it turns out that the extension of any theory can be computed in time linear to the size of the theory itself.
 

Guido Governatori and Antonino Rotolo.

An algorithm for business process compliance. In Enrico Francesconi, Giovani Sartor, and Daniela Tiscornia, editors, Legal Knowledge and Information Systems (Jurix 2008), Frontieres in Artificial Intelligence and Applications 189, pages 186-191. IOS Press, 2008.
Abstract: This paper provides a novel mechanism to check whether business processes are compliant with business rules regulating them. The key point is that compliance is a relationship between two sets of specifications: the specifications for executing a business process and the specifications regulating it.
 

Guido Governatori and Antonino Rotolo.

BIO logical agents: Norms, beliefs, intentions in defeasible logic. Journal of Autonomous Agents and Multi Agent Systems, 2008. Copyrigth © 2008 Springer.
Abstract: In this paper we follow the BOID (Belief, Obligation, Intention, Desire) architecture to describe agents and agent types in Defeasible Logic. We argue, in particular, that the introduction of obligations can provide a new reading of the concepts of intention and intentionality. Then we examine the notion of social agent (i.e., an agent where obligations prevail over intentions) and discuss some computational and philosophical issues related to it. We show that the notion of social agent either requires more complex computations or has some philosophical drawbacks.
 

Guido Governatori and Antonino Rotolo.

Changing legal systems: Abrogation and annulment. Part I: Revision of defeasible theories. In Ron van der Meyden and Leon van der Torre, editors, 9th International Conference on Deontic Logic in Computer Science (DEON2008), Lecture Notes in Computer Science. Springer, 2008. Copyrigth © 2008 Springer.
Abstract: In this paper we investigate how to model legal abrogation and annulment in Defeasible Logic. We examine some options that embed in this setting, and similar rule-based systems, ideas from belief and base revision. In both cases, our conclusion is negative, which suggests to adopt a different logical model.
 

Guido Governatori and Antonino Rotolo.

Changing legal systems: Abrogation and annulment. Part II: Temporalised defeasible logic. In Guido Boella, Harko Verhagen, and Muindhar Singh, editors, Proceedings of Normative Multi Agent Systems (NorMAS 2008, Luxembourg 15-16 July 2008.
Abstract: In this paper we propose a temporal extension of Defeasible Logic to model legal modifications, such as abrogation and annulment. Hence, this framework overcomes the difficulty, discussed elsewhere \cite{deon-part1}, of capturing these modification types using belief and base revision.
 

Guido Governatori, Antonino Rotolo and Vineet Padmanabhan.

The Cost of Social Agents. In 5th International Conference on Autonomous Agents and Multi-Agent Systems (AAMAS06), ACM Press, 2006. Copyright © 2006 ACM.
Abstract: In this paper we follow the BOID (Belief, Obligation, Intention, Desire) architecture to describe agents and agent types in Defeasible Logic. We argue that the introduction of obligations can provide a new reading of the concepts of intention and intentionality. Then we examine the notion of social agent (i.e., an agent where obligations prevail over intentions) and discuss some computational and philosophical issues related to it. We show that the notion of social agent either requires more complex computations or has some philosophical drawbacks.
 

Guido Governatori, Antonino Rotolo, Régis Riveret, Monica Palmirani and Giovanni Sartor.

Variations of Temporal Defeasible Logic for Modelling Norm Modifications. In Radboud Winkels, editor, Proceedings of 11th International Conference on Artificial Intelligence and Law, 155-159. ACM Press, New York, 2007. Copyright © 2007 ACM
Abstract: This paper proposes some variants of Temporal Defeasible Logic (TDL) to reason about normative modifications. These variants make it possible to differentiate cases in which, for example, modifications at some time change legal rules but their conclusions persist afterwards from cases where also their conclusions are blocked.
 

Guido Governatori, Antonino Rotolo, and Giovanni Sartor.

Temporalised normative positions in defeasible logic. In Anne Gardner, editor, Procedings of the 10th International Conference on Artificial Intelligence and Law, pages 25-34. ACM Press, 6-10 June 2005, Copyrigth © 2005 ACM.
Abstract:We propose a computationally oriented non-monotonic multi-modal logic arising from the combination of temporalised agency and temporalised normative positions. We argue about the defeasible nature of these notions and then we show how to represent and reason with them in the setting of Defeasible Logic.
 

Guido Governatori and Shazia Sadiq.

The journey to business process compliance. In Jorge Cardoso and Wil van der Aalst, editors, Handbook of Research on BPM, IGI Global, 2009.
Abstract: It is a typical scenario that many organisations have their business processes specified independently of their business obligations (which includes contractual obligations to business partners, as well as obligations a business has to fulfil against regulations and industry standards). This is because of the lack of guidelines and tools that facilitate derivation of processes from contracts but also because of the traditional mindset of treating contracts separately from business processes. This chapter will provide a solution to one specific problem that arises from this situation, namely the lack of mechanisms to check whether business processes are compliant with business contracts. The chapter begins by defining the space for business process compliance and the eco-system for ensuring that process are compliant. The key point is that compliance is a relationship between two sets of specifications: the specifications for executing a business process and the specifications regulating a business. The central part of the chapter focuses on a logic based formalism for describing both the semantics of normative specifications and the semantics of compliance checking procedures.
 

Guido Governatori and Andrew Stranieri.

Towards the application of association rules for defeasible rules discovery. In Bart Verheij, Arno Lodder, Ronald P. Loui, and Antoniette J. Muntjerwerff, editors, Legal Knowledge and Information Systems, pages 63-75, Amsterdam, 2001. JURIX, IOS Press.
Abstract:In this paper we investigate the feasibility of Knowledge Discovery from Database (KDD) in order to facilitate the discovery of defeasible rules that represent the ratio decidendi underpinning legal decision making. Moreover we will argue in favour of Defeasible Logic as the appropriate formal system in which the extracted principles should be encoded.
 

Guido Governatori and Duy~Hoang Pham.

A defeasible logic for modelling policy-based intentions and motivational attitudes. International Journal of Business Process Integration and Management, 5(4), 2009.
Abstract: We introduce the DR-CONTRACT architecture to represent and reason on e-Contracts. The architecture extends the DR-device architecture by a deontic defeasible logic of violation. We motivate the choice for the logic and we show how to extend RuleML to capture the notions relevant to describe e-contracts for a monitoring perspective in Defeasible Logic.
 

Guido Governatori, Subhasis Thakur, and Duy Hoang Pham.

A compliance model of trust. In Enrico Francesconi, Giovani Sartor, and Daniela Tiscornia, editors, Legal Knowledge and Information Systems (Jurix 2008), Frontieres in Artificial Intelligence and Applications 189, pages 118-127. IOS Press, 2008.
Abstract: We present a model of past interaction trust model based on compliance of expected behaviours.
 

Benjamin Johnston and Guido Governatori.

Induction of defeasible logic theories in the legal domain. In Giovanni Sartor, editor, Procedings of the 9th International Conference on Artificial Intelligence and Law, pages 204-213. IAAIL, ACM Press, 2003. Copyrigth © 2003 ACM.
Abstract:The market for intelligent legal information systems remains relatively untapped and while this might be interpreted as an indication that it is simply impossible to produce a system that satisfies the needs of the legal community, an analysis of previous attempts at producing such systems reveals a common set of deficiencies that in-part explain why there have been no overwhelming successes to date. Defeasible logic, a logic with proven successes at representing legal knowledge, seems to overcome many of these deficiencies and is a promising approach to representing legal knowledge. Unfortunately, an immediate application of technology to the challenges in this domain is an expensive and computationally intractable problem. So, in light of the benefits, we seek to find a practical algorithm that uses heuristics to discover an approximate solution. As an outcome of this work, we have developed an algorithm that integrates defeasible logic into a decision support system by automatically deriving its knowledge from databases of precedents. Experiments with the new algorithm are very promising - delivering results comparable to and exceeding other approaches.
 

Vineet Padmanabhan, Guido Governatori, Shazia Sadiq, Robert Colomb and Antonino Rotolo.

Process Modelling: The Deontic Way. In Markus Stumptner, Sven Hartmann and Yasushi Kiyoki, editors, Database Technology 2006, number 53 in Conference Research and Practice of Information Technology. Australian Computer Science Association, ACS, 16-19 January 2006. Copyrigth © 2006 ACS.
Abstract:Current enterprise systems rely heavily on the modelling and enactment of business processes. One of the key criteria for a business process is to represent not just the behaviours of the participants but also how the contractual relationships among them evolve over the course of an interaction. In this paper we provide a framework in which one can define policies/ business rules using deontic assignments to represent the contractual relationships. To achieve this end we use a combination of deontic/normative concepts like proclamation, directed obligation and direct action to account for a deontic theory of commitment which in turn can be used to model business processes in their organisational settings. In this way we view a business process as a social interaction process for the purpose of doing business. Further, we show how to extend the i^* framework, a well known organisational modelling technique, so as to accommodate our notion of deontic dependency.
 

Régis Riveret, Antonino Rotolo and Guido Governatori.

Interaction between Normative Systems and Cognitive agents in Temporal Modal Defeasible Logic. In Guido Boella, Leon van der Torre and Harko Verhagen, editors, Normative Multi-agent Systems. Dagstuhl Seminar Proceedings 7122. Internationales Begegnungs- und Forschungszentrum fuer Informatik (IBFI), Schloss Dagstuhl, Germany, Dagstuhl, Germany, 2007.
Abstract: While some recent frameworks on cognitive agents addressed the combination of mental attitudes with deontic concepts, they commonly ignore the representation of time. We propose in this paper a variant of Temporal Modal Defeasible Logic to deal in particular with temporal intervals.
 

Bram Roth, Régis Riveret, Antonino Rotolo and Guido Governatori.

Strategic Argumentation: A Game Theoretical Investigation. In Radboud Winkels, editor, Proceedings of 11th International Conference on Artificial Intelligence and Law, pp. 81-90. ACM Press, New York, 2007. Copyright © 2007 ACM
Abstract: Argumentation is modelled as a game where the payoffs are measured in terms of the probability that the claimed conclusion is, or is not, defeasibly provable, given a history of arguments that have actually been exchanged, and given the probability of the factual premises. The probability of a conclusion is calculated using a standard variant of Defeasible Logic, in combination with standard probability calculus. It is a new element of the present approach that the exchange of arguments is analysed with game theoretical tools, yielding a prescriptive and to some extent even predictive account of the actual course of play. A brief comparison with existing argument-based dialogue approaches confirms that such a prescriptive account of the actual argumentation has been almost lacking in the approaches proposed so far.
 

Miao Wang and Guido Governatori.

A Logic Framework of Normative-based Contract Management. Formal Methods in Electronic Commerce 2007. Stanford University, Palo Alto, CA. June 4, 2007.
Abstract: We explore of the feasibility of the computationally oriented institutional agency framework proposed by Governatori and Rotolo testing it against an industrial strength scenario. In particular we show how to encode in defeasible logic the dispute resolution policy described in Article 67 of FIDIC.