Sanjay Modgil

AIIM Journal 2026 Journal Article

Learning Health Systems provide a glide path to safe landing for AI in health

• Vasa Curcin
• Brendan Delaney
• Ahmad Alkhatib
• Neil Cockburn
• Olivia Dann
• Olga Kostopoulou
• Daniel Leightley
• Matthew Maddocks

Artificial Intelligence (AI) holds significant promise for healthcare but often struggles to transition from development to clinical integration. This paper argues that Learning Health Systems (LHS)-socio-technical ecosystems designed for continuous data-driven improvement-provide a potential "glide path" for safe, sustainable AI deployment. Just as modern aviation depends on instrument landing systems, the safe and effective integration of AI into healthcare requires the socio-technical infrastructure of LHSs, that enable iterative development and monitoring of AI tools, integrating clinical, technical, and ethical considerations through stakeholder collaboration. They address key challenges in AI implementation, including model generalizability, workflow integration, and transparency, by embedding co-creation, real-world evaluation, and continuous learning into care processes. Unlike static deployments, LHSs support the dynamic evolution of AI systems, incorporating feedback and recalibration to mitigate performance drift and bias. Moreover, they embed governance and regulatory functions-clarifying accountability, supporting data and model provenance, and upholding FAIR (Findable, Accessible, Interoperable, Reusable) principles. LHSs also promote "human-in-the-loop" safety through structured studies of human-AI interaction and shared decision-making. The paper outlines practical steps to align AI with LHS frameworks, including investment in data infrastructure, continuous model monitoring, and fostering a learning culture. Embedding AI in LHSs transforms implementation from a one-time event into a sustained, evidence-based learning process that aligns innovation with clinical realities, ultimately advancing patient care, health equity, and system resilience. The arguments build on insights from an international workshop hosted in 2025, offering a strategic vision for the future of AI in healthcare.

FLAP Journal 2025 Journal Article

Depth-bounded Reasoning in First-order Logic

• Marcello D’Agostino
• Costanza Larese
• Sanjay Modgil

Various suggestions as to what constitutes a “logic”, the product of multiple discussions with Dov Gabbay, are summarized.

ECAI Conference 2024 Conference Paper

EthiX: A Dataset for Argument Scheme Classification in Ethical Debates

• Elfia Bezou-Vrakatseli
• Oana Cocarascu
• Sanjay Modgil

Argument schemes represent stereotypical patterns of reasoning that capture the inferences from premise(s) to conclusion. Despite their usefulness in argument mining, argument scheme classification remains a largely understudied task in NLP. In this paper, we present EthiX, a novel dataset for classifying argument schemes, comprising arguments spanning 22 ethical topics which are manually annotated with argument schemes following Walton’s taxonomy. We evaluate pre-trained models fine-tuned on our dataset and propose a baseline to the community.

AAAI Conference 2024 Conference Paper

Moral Uncertainty and the Problem of Fanaticism

• Jazon Szabo
• Natalia Criado
• Jose Such
• Sanjay Modgil

While there is universal agreement that agents ought to act ethically, there is no agreement as to what constitutes ethical behaviour. To address this problem, recent philosophical approaches to `moral uncertainty' propose aggregation of multiple ethical theories to guide agent behaviour. However, one of the foundational proposals for aggregation - Maximising Expected Choiceworthiness (MEC) - has been criticised as being vulnerable to fanaticism; the problem of an ethical theory dominating agent behaviour despite low credence (confidence) in said theory. Fanaticism thus undermines the `democratic' motivation for accommodating multiple ethical perspectives. The problem of fanaticism has not yet been mathematically defined. Representing moral uncertainty as an instance of social welfare aggregation, this paper contributes to the field of moral uncertainty by 1) formalising the problem of fanaticism as a property of social welfare functionals and 2) providing non-fanatical alternatives to MEC, i.e. Highest k-trimmed Mean and Highest Median.

EUMAS Conference 2022 Conference Paper

Integrating Quantitative and Qualitative Reasoning for Value Alignment

• Jazon Szabo
• Jose M. Such
• Natalia Criado
• Sanjay Modgil

Abstract Agents that focus only on achieving their own goals may cause significant harm to society. As a result, when deciding which actions to perform, agents have to consider societal values and how their actions impact these values—the ‘value alignment problem’. There is therefore a need to integrate quantitative machine reasoning with an ability to reason about qualitative human values. In this paper, we present a novel framework for value-based reasoning that aims to bridge the gap between these two modes of reasoning. In particular, our framework extends the theory of grading to model how societal values can trade off with each other or with the agent’s goals. Furthermore, our framework introduces the use of hyperreal numbers to represent both quantitative and qualitative aspects of reasoning and help address the value alignment problem.

IS Journal 2021 Journal Article

Applying Metalevel Argumentation Frameworks to Support Medical Decision Making

• Nadin Kokciyan
• Isabel Sassoon
• Elizabeth Sklar
• Sanjay Modgil
• Simon Parsons

People are increasingly employing artificial intelligence as the basis for decision-support systems (DSSs) to assist them in making well-informed decisions. Adoption of DSS is challenging when such systems lack support, or evidence, for justifying their recommendations. DSSs are widely applied in the medical domain, due to the complexity of the domain and the sheer volume of data that render manual processing difficult. This article proposes a metalevel argumentation-based decision-support system that can reason with heterogeneous data (e. g. , body measurements, electronic health records, clinical guidelines), while incorporating the preferences of the human beneficiaries of those decisions. The system constructs template-based explanations for the recommendations that it makes. The proposed framework has been implemented in a system to support stroke patients and its functionality has been tested in a pilot study. User feedback shows that the system can run effectively over an extended period.

FLAP Journal 2021 Journal Article

Towards Depth-bounded Natural Deduction for Classical First-order Logic.

• Marcello D'Agostino
• Costanza Larese
• Sanjay Modgil

In this paper we lay the foundations of a new proof-theory for classical first-order logic that allows for a natural characterization of a notion of inferential depth. The approach we propose here aims towards extending the proof-theoretical framework presented in [6] by combining it with some ideas inspired by Hintikka’s work [18]. Unlike standard natural deduction, in this framework the inference rules that fix the meaning of the logical operators are symmetrical with respect to assent and dissent and do not involve the discharge of formulas. The only discharge rule is a classical dilemma rule whose nested applications provide a sensible measure of inferential depth. The result is a hierarchy of decidable depth-bounded approximations of classical first-order logic that expands the hierarchy of tractable approximations of Boolean logic investigated in [11, 10, 7].

IJCAI Conference 2020 Conference Paper

A Fully Rational Account of Structured Argumentation Under Resource Bounds

• Marcello D'Agostino
• Sanjay Modgil

ASPIC+ is an established general framework for argumentation and non-monotonic reasoning. However, ASPIC+ does not satisfy the non-contamination rationality postulates, and moreover, tacitly assumes unbounded resources when demonstrating satisfaction of the consistency postulates. In this paper we present a new version of ASPIC+ – Dialectial ASPIC+ – that is fully rational under resource bounds.

EUMAS Conference 2020 Conference Paper

An Argumentation-Based Approach to Generate Domain-Specific Explanations

• Nadin Kökciyan
• Simon Parsons
• Isabel Sassoon
• Elizabeth Sklar
• Sanjay Modgil

Abstract In argumentation theory, argument schemes are constructs to generalise common patterns of reasoning; whereas critical questions (CQs) capture the reasons why argument schemes might not generate arguments. Argument schemes together with CQs are widely used to instantiate arguments; however when it comes to making decisions, much less attention has been paid to the attacks among arguments. This paper provides a high-level description of the key elements necessary for the formalisation of argumentation frameworks such as argument schemes and CQs. Attack schemes are then introduced to represent attacks among arguments, which enable the definition of domain-specific attacks. One algorithm is articulated to operationalise the use of schemes to generate an argumentation framework, and another algorithm to support decision making by generating domain-specific explanations. Such algorithms can then be used by agents to make recommendations and to provide explanations for humans. The applicability of this approach is demonstrated within the context of a medical case study.

AAMAS Conference 2019 Conference Paper

Computational Argumentation-based Clinical Decision Support

• Martin Chapman
• Panagiotis Balatsoukas
• Mark Ashworth
• Vasa Curcin
• Nadin Kökciyan
• Kai Essers
• Isabel Sassoon
• Sanjay Modgil

This demonstration highlights the design of the Consult system, a modular decision-support system (DSS) intended to help patients suffering from chronic conditions self-manage their treatments. The system takes input from multiple sources, including commercial wellness sensors and a patient’s electronic health record, to inform a computational argumentation engine that constructs weighted opinions using these inputs and knowledge about their sources, and uses an interaction agent driven by argumentation-based dialogue to respond to user queries.

LORI Conference 2019 Conference Paper

Evaluating Networks of Arguments: A Case Study in Mīmāṃsā Dialectics

• Kees van Berkel 0002
• Agata Ciabattoni
• Elisa Freschi
• Sanjay Modgil

Abstract We formalize networks of authored arguments. These networks are then mapped to \(ASPIC{^+}\) theories that subsequently instantiate Extended Argumentation Frameworks. Evaluation of arguments in the latter determines the status of the arguments in the source networks. The methodology is illustrated through a collaboration between scholars of South Asian philosophy, logicians and formal argumentation theorists, analyzing excerpts of Sanskrit texts concerning a controversial normative debate within the philosophical school of Mīmāṃsā.

AIJ Journal 2019 Journal Article

On the graded acceptability of arguments in abstract and instantiated argumentation

• Davide Grossi
• Sanjay Modgil

The paper develops a formal theory of the degree of justification of arguments, which relies solely on the structure of an argumentation framework, and which can be successfully interfaced with approaches to instantiated argumentation. The theory is developed in three steps. First, the paper introduces a graded generalization of the two key notions underpinning Dung's semantics: self-defense and conflict-freeness. This leads to a natural generalization of Dung's semantics, whereby standard extensions are weakened or strengthened depending on the level of self-defense and conflict-freeness they meet. The paper investigates the fixpoint theory of these semantics, establishing existence results for them. Second, the paper shows how graded semantics readily provide an approach to argument rankings, offering a novel contribution to the recently growing research programme on ranking-based semantics. Third, this novel approach to argument ranking is applied and studied in the context of instantiated argumentation frameworks, and in so doing is shown to account for a simple form of accrual of arguments within the Dung paradigm. Finally, the theory is compared in detail with existing approaches.

IJCAI Conference 2018 Conference Paper

A Study of Argumentative Characterisations of Preferred Subtheories

• Marcello D'Agostino
• Sanjay Modgil

Classical logic argumentation (Cl-Arg) under the stable semantics yields argumentative characterisations of non-monotonic inference in Preferred Subtheories. This paper studies these characterisations under both the standard approach to Cl-Arg, and a recent dialectical approach that is provably rational under resource bounds. Two key contributions are made. Firstly, the preferred extensions are shown to coincide with the stable extensions. This means that algorithms and proof theories for the admissible semantics can now be used to decide credulous inference in Preferred Subtheories. Secondly, we show that as compared with the standard approach, the grounded semantics applied to the dialectical approach more closely approximates sceptical inference in Preferred Subtheories.

AIJ Journal 2018 Journal Article

Corrigendum to “A general account of argumentation with preferences” [Artif. Intell. 195 (2013) 361–397]

• Sanjay Modgil
• Henry Prakken

ASPIC + is a general framework for structured argumentation that allows for a considerable degree of freedom as to the knowledge representation choices made in specifying the premises and rules from which arguments are constructed, and the preferences used to determine which attacks amongst constructed arguments succeed as defeats. On the other hand, the framework provides guidelines for making these choices, such that adherence to these guidelines suffices to guarantee satisfaction of the consistency and closure postulates. In particular, guidelines are given for selecting ways in which to compare the sets of defeasible constituents of arguments in order that the defined preference relations over arguments guarantee satisfaction of the rationality postulates. However, it has recently been noted that the way in which these set comparisons are made, and the guidelines for choosing these comparisons, admit counter-examples to these postulates. This research note proposes simple revisions to the ASPIC + framework as defined in [3]. In this way, the counter-examples are avoided and rationality is preserved.

FLAP Journal 2017 Journal Article

Abstract Rule-Based Argumentation.

• Sanjay Modgil
• Henry Prakken

This article reviews abstract rule-based approaches to argumentation, in particular the ASPIC + framework. In ASPIC + and its predecessors, going back to the seminal work of John Pollock, arguments can be formed by combining strict and defeasible inference rules and conflicts between arguments can be resolved in terms of a preference relation on arguments. This results in abstract argumentation frameworks (a set of arguments with a binary relation of defeat), so that arguments can be evaluated with the theory of abstract argumentation. First the basic ASPIC + framework is reviewed, possible ways to instantiate it are discussed and how these instantiations can satisfy closure and consistency properties. Then the relation between ASPIC + and other work in formal argumentation and nonmonotonic logic is discussed, including a review of how other approaches can be reconstructed as instantiations of ASPIC +. Further developments and variants of the basic ASPIC + framework are also reviewed, including developments with alternative or generalised notions of attack and defeat and variants with further constraints on arguments. Finally, implementations and applications of ASPIC + are briefly reviewed and some open problems and avenues for further research are discussed.

AILAW Journal 2017 Journal Article

Norms and value based reasoning: justifying compliance and violation

• Trevor Bench-Capon
• Sanjay Modgil

Abstract There is an increasing need for norms to be embedded in technology as the widespread deployment of applications such as autonomous driving, warfare and big data analysis for crime fighting and counter-terrorism becomes ever closer. Current approaches to norms in multi-agent systems tend either to simply make prohibited actions unavailable, or to provide a set of rules (principles) which the agent is obliged to follow, either as part of its design or to avoid sanctions and punishments. In this paper we argue for the position that agents should be equipped with the ability to reason about a system’s norms, by reasoning about the social and moral values that norms are designed to serve; that is, perform the sort of moral reasoning we expect of humans. In particular we highlight the need for such reasoning when circumstances are such that the rules should arguably be broken, so that the reasoning can guide agents in deciding whether to comply with the norms and, if violation is desirable, how best to violate them. One approach to enabling this is to make use of an argumentation scheme based on values and designed for practical reasoning: arguments for and against actions are generated using this scheme and agents choose between actions based on their preferences over these values. Moral reasoning then requires that agents have an acceptable set of values and an acceptable ordering on their values. We first discuss how this approach can be used to think about and justify norms in general, and then discuss how this reasoning can be used to think about when norms should be violated, and the form this violation should take. We illustrate how value based reasoning can be used to decide when and how to violate a norm using a road traffic example. We also briefly consider what makes an ordering on values acceptable, and how such an ordering might be determined.

ECAI Conference 2016 Conference Paper

A Rational Account of Classical Logic Argumentation for Real-World Agents

• Marcello D'Agostino
• Sanjay Modgil

Classical logic based argumentation (ClAr) characterises single agent non-monotonic reasoning and enables distributed non-monotonic reasoning amongst agents in dialogues. However, features of ClAr that have been shown sufficient to ensure satisfaction of rationality postulates, preclude their use by resource bounded agents reasoning individually, or dialectically in real-world dialogue. This paper provides a new formalisation of ClAr that is both suitable for such uses and satisfies the rationality postulates. We illustrate by providing a rational dialectical characterisation of Brewka's non-monotonic Preferred Subtheories defined under the assumption of restricted inferential capabilities.

AAMAS Conference 2016 Conference Paper

Estimating Second-Order Arguments in Dialogical Settings (Extended Abstract)

• Seyed Ali Hosseini
• Sanjay Modgil
• Odinaldo Rodrigues

This paper proposes mechanisms for agents to model other agents’ arguments, so that modelling agents can anticipate the likelihood that their interlocutors can constructs arguments in dialogues. In contrast with existing works on “opponent modelling” which treat arguments as abstract entities, the likelihood that an agent can construct an argument is derived from the likelihoods that it possesses the beliefs required to construct the argument. We therefore also address how a modeller can quantify the certainty that its interlocutor possesses beliefs based on previous dialogues, and membership of interlocutors in communities.

AAMAS Conference 2016 Conference Paper

Prioritised Default Logic as Rational Argumentation

• Anthony P. Young
• Sanjay Modgil
• Odinaldo Rodrigues

We endow Brewka’s prioritised default logic (PDL) with argumentation semantics using the ASPIC+ framework for structured argumentation. We prove that the conclusions of the justified arguments correspond to the prioritised default extensions in a normatively rational manner. Argumentation semantics for PDL will allow for the application of argument game proof theories to the process of inference in PDL, making the reasons for accepting a conclusion transparent and the inference process more intuitive. This also opens up the possibility for argumentation-based distributed reasoning and communication amongst agents with PDL representations of mental attitudes. General Terms Theory

AILAW Journal 2015 Journal Article

Monitoring compliance with E-contracts and norms

• Sanjay Modgil
• Nir Oren
• Noura Faci
• Felipe Meneguzzi
• Simon Miles
• Michael Luck

Abstract The behaviour of autonomous agents may deviate from that deemed to be for the good of the societal systems of which they are a part. Norms have therefore been proposed as a means to regulate agent behaviours in open and dynamic systems, where these norms specify the obliged, permitted and prohibited behaviours of agents. Regulation can effectively be achieved through use of enforcement mechanisms that result in a net loss of utility for an agent in cases where the agent’s behaviour fails to comply with the norms. Recognition of compliance is thus crucial for achieving regulation. In this paper, we propose a general framework for observation of agents’ behaviour, and recognition of this behaviour as constituting, or counting as, compliance or violation. The framework deploys monitors that receive inputs from trusted observers, and processes these inputs together with transition network representations of individual norms. In this way, monitors determine the fulfillment or violation status of norms. The paper also describes a proof of concept implementation of the framework, and its deployment in electronic contracting environments.

IJCAI Conference 2015 Conference Paper

On the Graded Acceptability of Arguments

• Davide Grossi
• Sanjay Modgil

The paper develops a formal theory of the degree of justification of arguments, which relies solely on the structure of an argumentation framework. The theory is based on a generalisation of Dung’s notion of acceptability, making it sensitive to the numbers of attacks and counter-attacks on arguments. Graded generalisations of argumentation semantics are then obtained and studied. The theory is applied by showing how it can arbitrate between competing preferred extensions and how it captures a specific form of accrual in instantiated argumentation.

AIJ Journal 2013 Journal Article

A general account of argumentation with preferences

• Sanjay Modgil
• Henry Prakken

This paper builds on the recent ASPIC + formalism, to develop a general framework for argumentation with preferences. We motivate a revised definition of conflict free sets of arguments, adapt ASPIC + to accommodate a broader range of instantiating logics, and show that under some assumptions, the resulting framework satisfies key properties and rationality postulates. We then show that the generalised framework accommodates Tarskian logic instantiations extended with preferences, and then study instantiations of the framework by classical logic approaches to argumentation. We conclude by arguing that ASPIC + ʼs modelling of defeasible inference rules further testifies to the generality of the framework, and then examine and counter recent critiques of Dungʼs framework and its extensions to accommodate preferences.

IJCAI Conference 2013 Conference Paper

Opponent Modelling in Persuasion Dialogues

• Christos Hadjinikolis
• Yiannis Siantos
• Sanjay Modgil
• Elizabeth Black
• Peter McBurney

A strategy is used by a participant in a persuasion dialogue to select locutions most likely to achieve its objective of persuading its opponent. Such strategies often assume that the participant has a model of its opponents, which may be constructed on the basis of a participant’s accumulated dialogue experience. However in most cases the fact that an agent’s experience may encode additional information which if appropriately used could increase a strategy’s efficiency, is neglected. In this work, we rely on an agent’s experience to define a mechanism for augmenting an opponent model with information likely to be dialectally related to information already contained in it. Precise computation of this likelihood is exponential in the volume of related information. We thus describe and evaluate an approximate approach for computing these likelihoods based on Monte-Carlo simulation.

EAAI Journal 2012 Journal Article

Applying electronic contracting to the aerospace aftercare domain

• Felipe Meneguzzi
• Sanjay Modgil
• Nir Oren
• Simon Miles
• Michael Luck
• Noura Faci

The contract project was a European Commission project whose aim was to develop frameworks, components and tools to model, build, verify and monitor distributed electronic business systems based on electronic contracts. In this context, an electronic contract provides a specification of the expected behaviours of individual services, with the assumption that these services are often enacted by autonomous agents. Using the theoretical tools created by the project, in this paper we describe the complete life cycle of instantiating an electronic contracting system using the contract framework within the aerospace aftercare domain. Thus, we use a natural language description of parts of the types of contracts used in this domain to generate individual norms amenable to a computational representation, and how these norms are used to generate a concrete contract monitor. Moreover, we describe a concrete implementation of contract agents in the AgentSpeak(L) language and how these agents interact within a concrete instantiation of contract.

JAAMAS Journal 2011 Journal Article

Deliberation dialogues for reasoning about safety critical actions

• Pancho Tolchinsky
• Sanjay Modgil
• Ulises Cortés

Abstract In this paper we present the argument-based model proCLAIM, intended to provide a setting for heterogeneous agents to deliberate over safety critical actions. To achieve this purpose proCLAIM features a Mediator Agent with three main tasks: (1) guiding the participating agents in what their valid dialectical moves are at each stage of the dialogue; (2) deciding whether submitted arguments should be accepted on the basis of their relevance; and finally, (3) evaluating the accepted arguments in order to provide an assessment of whether the proposed action should or should not be undertaken. The main focus in this paper is the proposal of a set of reasoning patterns, represented in terms of argument schemes and critical questions, intended to automatise deliberations on whether a proposed action can safely be performed. We aim to motivate the importance of these schemes and critical questions for: (a) the Mediator Agent’s guiding task that allows for a highly focused deliberation; (b) the effective participation of heterogeneous agents; and (c) enabling the reuse of previous similar deliberations in order to evaluate arguments on an evidential basis.

IJCAI Conference 2011 Conference Paper

Revisiting Preferences and Argumentation

• Sanjay Modgil
• Henry Prakken

The ASPIC+ framework is intermediate in abstraction between Dung's argumentation framework and concrete instantiating logics. This paper generalises ASPIC+ to accommodate classical logic instantiations, and adopts a new proposal for evaluating extensions: attacks are used to define the notion of conflict-free sets, while the defeats obtained by applying preferences to attacks, are exclusively used to determine the acceptability of arguments. Key properties and rationality postulates are then shown to hold for the new framework.

ECAI Conference 2010 Conference Paper

Computation in Extended Argumentation Frameworks

• Paul E. Dunne
• Sanjay Modgil
• Trevor J. M. Bench-Capon

Extended Argumentation Frameworks (EAFs) are a recently proposed formalism that develop abstract argumentation frameworks (AFs) by allowing attacks between arguments to be attacked themselves: hence EAFs add a relationship [Dscr ] ⊆ [Xscr ] × [Ascr ] to the arguments ([Xscr ]) and attacks ([Ascr ] ⊆ [Xscr ] × [Xscr ]) in an AF's basic directed graph structure 〈[Xscr ], [Ascr ]〉. This development provides a natural way to represent and reason about preferences between arguments. Studies of EAFs have thus far focussed on acceptability semantics, proof-theoretic processes, and applications. However, no detailed treatment of their practicality in computational settings has been undertaken. In this paper we address this lacuna, considering algorithmic and complexity properties specific to EAFs. We show that (as for standard AFs) the problem of determining if an argument is acceptable w. r. t. a subset of [Xscr ] is polynomial time decidable and, thus, determining the grounded extension and verifying admissibility are efficiently solvable. We, further, consider the status of a number of decision questions specific to the EAF formalism in the sense that these have no counterparts within AFs.

IJCAI Conference 2009 Conference Paper

• Sanjay Modgil

Dung’s abstract theory of argumentation has become established as a general framework for various species of non-monotonic reasoning, and reasoning in the presence of conflict. A Dung framework consists of arguments related by attacks, and the extensions of a framework, and so the status of arguments, are defined under different semantics. Developments of Dung’s work have also de- fined argument labellings as an alternative way of characterising extensions, and dialectical argument game proof theories for establishing the status of individual arguments. Recently, Extended Argumentation Frameworks extend Dung’s theory so that arguments not only attack arguments, but attacks themselves. In this way, the extended theory provides an abstract framework for principled integration of meta-level argumentation about defeasible preferences applied to resolve conflicts between object level arguments. In this paper we formalise labellings and argument games for a selection of Dung’s semantics defined for the extended frameworks.

AAMAS Conference 2009 Conference Paper

A Framework for Monitoring Agent-Based Normative Systems

• Sanjay Modgil
• Noura Faci
• Felipe Meneguzzi
• Nir Oren
• Simon Miles
• Michael Luck

The behaviours of autonomous agents may deviate from those deemed to be for the good of the societal systems of which they are a part. Norms have therefore been proposed as a means to regulate agent behaviours in open and dynamic systems, where these norms specify the obliged, permitted and prohibited behaviours of agents. Regulation can effectively be achieved through use of enforcement mechanisms that result in a net loss of utility for an agent in cases where the agent’s behaviour fails to comply with the norms. Recognition of compliance is thus crucial for achieving regulation. In this paper we propose a generic architecture for observation of agent behaviours, and recognition of these behaviours as constituting, or counting as, compliance or violation. The architecture deploys monitors that receive inputs from observers, and processes these inputs together with transition network representations of individual norms. In this way, monitors determine the fulfillment or violation status of norms. The paper also describes a proof of concept implementation and deployment of monitors in electronic contracting environments.

AIJ Journal 2009 Journal Article

Reasoning about preferences in argumentation frameworks

• Sanjay Modgil

The abstract nature of Dung's seminal theory of argumentation accounts for its widespread application as a general framework for various species of non-monotonic reasoning, and, more generally, reasoning in the presence of conflict. A Dung argumentation framework is instantiated by arguments and a binary conflict based attack relation, defined by some underlying logical theory. The justified arguments under different extensional semantics are then evaluated, and the claims of these arguments define the inferences of the underlying theory. To determine a unique set of justified arguments often requires a preference relation on arguments to determine the success of attacks between arguments. However, preference information is often itself defeasible, conflicting and so subject to argumentation. Hence, in this paper we extend Dung's theory to accommodate arguments that claim preferences between other arguments, thus incorporating meta-level argumentation based reasoning about preferences in the object level. We then define and study application of the full range of Dung's extensional semantics to the extended framework, and study special classes of the extended framework. The extended theory preserves the abstract nature of Dung's approach, thus aiming at a general framework for non-monotonic formalisms that accommodate defeasible reasoning about as well as with preference information. We illustrate by formalising argument based logic programming with defeasible priorities in the extended theory.

IS Journal 2007 Journal Article

Argumentation-Based Inference and Decision Making--A Medical Perspective

• John Fox
• David Glasspool
• Dan Grecu
• Sanjay Modgil
• MATTHEW SOUTH
• Vivek Patkar

The argumentation services platform with integrated components (Aspic) project aims to provide advanced argumentation-based computational capabilities. Argumentation is a potentially important paradigm for developing commercial and public services that are flexible and easily understood by human users.

IS Journal 2006 Journal Article

A Canonical Agent Model for Healthcare Applications

• John Fox
• David Glasspool
• Sanjay Modgil

Although the utility of autonomous agents and multiagent systems in healthcare applications is now well established, agent technologies themselves remain somewhat immature and, from a theoretical point of view, often ad hoc. We've developed a standard, or canonical, agent model that's intended to be both theoretically well motivated and technically well defined while permitting alternative instantiations. A general autonomous agent system architecture has emerged from the healthcare application domain. Twelve invariant input-output patterns, or signatures, summarize its component properties, and shared data structures define the component interactions

JELIA Conference 2006 Conference Paper

Hierarchical Argumentation

• Sanjay Modgil

Abstract In this paper we motivate and formalise a framework that organises Dung argumentation frameworks into a hierarchy. Argumentation over preference information in a level n Dung framework is then used to resolve conflicts between arguments in a level n-1 framework. We then re-examine the issue of Dung’s acceptability semantics for arguments from the perspective of hierarchical argumentation.

IS Journal 2006 Journal Article

Increasing Human-Organ Transplant Availability: Argumentation-Based Agent Deliberation

• Pancho Tolchinsky
• Ulises Cortes
• Sanjay Modgil
• Francisco Caballero
• Antonio Lopez-Navidad

Human-organ transplantation is the only effective therapy for many life-threatening diseases. However, despite an increase in transplant successes, the lack of a concomitant increase in donor organ availability has led to a growing disparity between supply and demand. Much research has thus focused on defining and implementing policies for increasing donor availability, identifying suitable organ recipients, and documenting transplant procedures. A novel organ-selection process uses a multiagent system called Carrel+ to let geographically dispersed transplant physicians deliberate over organ viability to increase the availability of organs for transplantation

KER Journal 2006 Journal Article

Towards an argument interchange format

• CARLOS CHESÑEVAR
• MCGINNIS
• Sanjay Modgil
• Iyad Rahwan
• Chris Reed
• GUILLERMO SIMARI
• MATTHEW SOUTH
• GERARD VREESWIJK

The theory of argumentation is a rich, interdisciplinary area of research straddling the fields of artificial intelligence, philosophy, communication studies, linguistics and psychology. In the last few years, significant progress has been made in understanding the theoretical properties of different argumentation logics. However, one major barrier to the development and practical deployment of argumentation systems is the lack of a shared, agreed notation or ‘interchange format’ for argumentation and arguments. In this paper, we describe a draft specification for an argument interchange format (AIF) intended for representation and exchange of data between various argumentation tools and agent-based applications. It represents a consensus ‘abstract model’ established by researchers across fields of argumentation, artificial intelligence and multi-agent systems. In its current form, this specification is intended as a starting point for further discussion and elaboration by the community, rather than an attempt at a definitive, all-encompassing model. However, to demonstrate proof of concept, a use case scenario is briefly described. Moreover, three concrete realizations or ‘reifications’ of the abstract model are illustrated.