Nir Oren's research while affiliated with University of Aberdeen and other places
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Publications (165)
Research has shown that cooperative action struggles to emerge in the noisy variant of the donation game, a simple model of noisy multi-agent systems where indirect reciprocity is required to maximise utility. Such noise can arise when agents may have an incorrect view of the reputation of their interaction partners, or when the actions themselves...
A gradual semantics takes a weighted argumentation framework as input and outputs a final acceptability degree for each argument, with different semantics performing the computation in different manners. In this work, we consider the problem of attack inference. That is, given a gradual semantics, a set of arguments with associated initial weights,...
Happiness, or subjective wellbeing, brings lasting positive effects to individuals, communities, and societies. Intentional engagement in kind behaviours can have a significant effect on increasing and sustaining subjective wellbeing in humans. In this paper we investigate the effectiveness of a behaviour change intervention for kindness and subjec...
A gradual semantics takes a weighted argumentation framework as input and outputs a final acceptability degree for each argument, with different semantics performing the computation in different manners. In this work, we consider the problem of attack inference. That is, given a gradual semantics, a set of arguments with associated initial weights,...
In this paper we illustrate how novel AI methods can improve the performance of intelligence analysts. These analysts aim to make sense of — often conflicting or incomplete — information, weighing up competing hypotheses which serve to explain an observed situation. Analysts have access to numerous visual analytic tools which support the temporal a...
Multi-agent systems is an evolving discipline that encompasses many different branches of research. The long-standing Agents at Aberdeen ( A 3 ) group undertakes research across several areas of multi-agent systems, focusing in particular on aspects related to resilience, reliability, and coordination. In this article we introduce the group and hig...
Gradual semantics with abstract argumentation provide each argument with a score reflecting its acceptability. Many different gradual semantics have been proposed in the literature, each following different principles and producing different argument rankings. A sub-class of such semantics, the so-called weighted semantics, takes, in addition to th...
![SimpleBDI semantics. ∅\documentclass[12pt]{minimal}...](publication/360472873/figure/fig1/AS:11431281093109601@1667099467129/SimpleBDI-semantics-documentclass12ptminimal-usepackageamsmath_Q320.jpg)
BDI agents act in response to external inputs and their internal plan library. Understanding the root cause of BDI agent action is often difficult, and in this paper we present a dialogue based approach for explaining the behaviour of a BDI agent. We consider two dialogue participants who may have different views regarding the beliefs, plans and ex...
In this paper, we place ourselves in the context of human robot interaction and address the problem of cognitive robot modelling. More precisely we are investigating properties of a utility-based model that will govern a robot's actions. The novelty of this approach lies in embedding the responsibility of the robot over the state of affairs into th...
Gradual semantics within abstract argumentation associate a numeric score with every argument in a system, which represents the level of acceptability of this argument, and from which a preference ordering over arguments can be derived. While some semantics operate over standard argumentation frameworks, many utilise a weighted framework, where a n...
Gradual semantics with abstract argumentation provide each argument with a score reflecting its acceptability, i.e. how "much" it is attacked by other arguments. Many different gradual semantics have been proposed in the literature, each following different principles and producing different argument rankings. A sub-class of such semantics, the so-...
Probabilistic argumentation combines probability theory and formal models of argumentation. Given an argumentation graph where vertices are arguments and edges are attacks or supports between arguments, the approach of probabilistic labellings relies on a probability space where the sample space is any specific set of argument labellings of the gra...
In this paper we describe an argumentation-based representation of normal form games, and demonstrate how argumentation can be used to compute pure strategy Nash equilibria. Our approach builds on Modgil’s Extended Argumentation Frameworks. We demonstrate its correctness, showprove several theoretical properties it satisfies, and outline how it can...
Various structured argumentation frameworks utilize preferences as part of their inference procedure. In this paper, we consider an inverse of the standard reasoning problem, seeking to identify what preferences could lead to a given set of conclusions being drawn. We ground our work in the Assumption-Based Argumentation (ABA) framework, and presen...
![Fig. 1: The evaluation matrix of security events as proposed in [1].](profile/Nasser-Al-Hadrami/publication/349232499/figure/fig1/AS:1032324779085824@1623136815000/The-evaluation-matrix-of-security-events-as-proposed-in-1_Q320.jpg)
We propose a novel attack tree model, called a subjective attack tree, aiming to address the limitations of traditional attack trees, which use precise values for likelihoods of security events. In many situations, it is often difficult to elicit accurate probabilities due to lack of knowledge, or insufficient historical data, making the evaluation...
Subjective attack trees are an extension to traditional attack trees, proposed so to take uncertainty about likelihoods of security events into account during the modelling of security risk scenarios, using subjective opinions. This paper extends the work of subjective attack trees by allowing for the modelling of countermeasures, as well as conduc...
Societal rules, as exemplified by norms, aim to provide a degree of behavioural stability to multi-agent societies. Norms regulate a society using the deontic concepts of permissions, obligations and prohibitions to specify what can, must and must not occur in a society. Many implementations of normative systems assume various combinations of the f...
What does it mean that something is probably obligatory? And how does it relate to the probability that it is permitted or prohibited? In this paper, we provide a possible answer by merging deontic argumentation and probabilistic argumentation into a probabilistic deontic argumentation framework. This framework allows us to specify a semantics for...
In this paper we describe an argumentation-based representation of normal form games, and demonstrate how argumentation can be used to compute pure strategy Nash equilibria. Our approach builds on Modgil's Extended Argumentation Frameworks. We demonstrate its correctness, prove several theoretical properties it satisfies, and outline how it can be...
Various structured argumentation frameworks utilize preferences as part of their standard inference procedure to enable reasoning with preferences. In this paper, we consider an inverse of the standard reasoning problem, seeking to identify what preferences over assumptions could lead to a given set of conclusions being drawn. We ground our work in...
We describe a tool for providing explanation of plans to non-technical users, built on formal argumentation and dialogue theory, and supported by natural language generation and visualisation technologies. We describe how arguments can be generated from domain rules, and how justified arguments can be identified through dialogue, allowing the syste...
Assessing whether an agent has abandoned a goal or is actively pursuing it is important when multiple agents are trying to achieve joint goals, or when agents commit to achieving goals for each other. Making such a determination for a single goal by observing only plan traces is not trivial, as agents often deviate from optimal plans for various re...
In a normative environment, an agent’s actions are directed not only by its goals but also by the norms activated by its actions and those of other actors. The potential for conflict between agent goals and norms makes decision making challenging, in that it requires looking ahead to consider the longer-term consequences of which goal to satisfy or...
Recognizing goals and plans from complete or partial observations can be efficiently achieved through automated planning techniques. In many applications, it is important to recognize goals and plans not only accurately, but also quickly. To address this challenge, we develop novel goal recognition approaches based on planning techniques that rely...
In this paper, we develop and validate a scale to measure the perceived persuasiveness of messages to be used in digital behaviour interventions. A literature review is conducted to inspire the initial scale items. The scale is developed using Exploratory and Confirmatory Factor Analysis on the data from a study with 249 ratings of healthy eating m...
Within multi-agent systems, some agents may delegate tasks to other agents for execution. Recursive delegation designates situations where delegated tasks may, in turn, be delegated onwards. In unconstrained environments, recursive delegation policies based on quitting games are known to outperform policies based on multi-armed bandits. In this wor...
Eigentrust is a simple and widely used algorithm, which quantifies trust based on the repeated application of an update matrix to a vector of initial trust values. In some cases, however, this procedure is rendered uninformative. Here, we characterise such situations and trace their origin to the algebraic conditions guaranteeing the convergence of...
The task of recognizing goals and plans from missing and full observations can be done efficiently by using automated planning techniques. In many applications, it is important to recognize goals and plans not only accurately, but also quickly. To address this challenge, we develop novel goal recognition approaches based on planning techniques that...
Assessing whether an agent has abandoned a goal or is actively pursuing it is important when multiple agents are trying to achieve joint goals, or when agents commit to achieving goals for each other. Making such a determination for a single goal by observing only plan traces is not trivial as agents often deviate from optimal plans for various rea...
Task delegation lies at the heart of the service economy, and is a fundamental aspect of many agent marketplaces. Research in computational trust considers which agent a task should be delegated to for execution given the agent’s past behaviour. However, such work does not consider the effects of the agent delegating the task onwards, forming a cha...
Artificial intelligence has been increasing the autonomy of man-made artefacts such as software agents, self-driving vehicles and military drones. This increase in autonomy together with the ubiquity and impact of such artefacts in our daily lives have raised many concerns in society. Initiatives such as transparent and ethical AI aim to allay fear...
Data sharing is becoming an integral part of many aspects of our daily lives. We propose a method for controlling access to data and knowledge through fine-grained, user-specified explicitly represented policies. We present an overview of a policy formalism and mechanisms to facilitate distributed data sharing. We provide a breakdown of how our app...
This paper describes an investigation into the effectiveness of ArguMessage, a system that uses argumentation schemes and limited user input to semi-automatically generate persuasive messages encouraging behaviour change that follow specific argumentation patterns. We conducted user studies in the domains of healthy eating and email security to inv...
Persuasive technologies use a variety of strategies and principles to encourage people to adopt and maintain beneficial behaviours and attitudes. In this paper we investigate the influence of Cialdini’s seven persuasive principles on people’s choices, actions and behaviour. In contrast to related work investigating perceived persusaion, this study...
Monitoring plan execution is useful in various multi-agent applications, from agent cooperation to norm enforcement. Realistic environments often impose constraints on the capabilities of such monitoring, limiting the amount and coverage of available sensors. In this paper, we consider the problem of sensor placement within an environment to determ...
We present an extension-based approach for computing preferences in an abstract argumentation system. Although numerous argumentation semantics have been developed previously for identifying acceptable sets of arguments from an argumentation framework, there is a lack of justification behind their acceptability based on implicit argument preference...
The conclusions drawn from a dialogue depend both on the content of the arguments, and the level of trust placed in the arguments and the entity advancing them. In this paper, we describe a framework for dialogue where such trust forms the basis for expressing preferences between arguments, and in turn, for computing conclusions of the dialogue. Ou...
Intentional engagement in positive activities, such as practicing kindness, showing generosity or expressing gratitude, can help people increase their happiness levels and improve their wellbeing. In this paper we explore how a gamified digital behaviour change intervention can be adapted to encourage people of different personality types to engage...
Participating in kindness activities, being generous and showing gratitude, can help people increase their overall happiness levels and improve their levels of wellbeing. This paper describes an installation which will run during the UMAP 2018 Conference. We demonstrate how a gamified digital behavior change intervention can be used to encourage pe...
Delegation allows an agent to request that another agent completes a task. In many situations the task may be delegated onwards, and this process can repeat until it is eventually, successfully or unsuccessfully, performed. We consider policies to guide an agent in choosing who to delegate to when such recursive interactions are possible. These pol...
This paper describes a system that uses argumentation
schemes and limited user input to automatically generate persuasive
messages that encourage behaviour change. We have used this system
in the domain of healthy eating, but are also exploring its use in
other domains such as behaviour change for cyber-security. The argumentation schemes used have...
This paper seeks to better understand the links between human reasoning and preferred extensions as found within formal argumentation, especially in the context of uncertainty. The degree of believability of a conclusion may be associated with the number of preferred extensions in which the conclusion is credulously accepted. We are interested in w...
In this paper we investigate the links between instantiated argumentation systems and the axioms for non-monotonic reasoning described in [15] with the aim of characterising the nature of argument based reasoning. In doing so, we consider two possible interpretations of the consequence relation, and describe which axioms are met by under each of th...
Market mechanisms are now playing a key role in the allocation and pricing of on-demand transportation services. In practice, most such services use posted-price mechanisms, where both passengers and drivers are offered a journey price which they can accept or reject. However, providers such as Liftago and GrabTaxi have begun to adopt a mechanism w...
To resolve conflicts among norms,various nonmonotonic formalisms can be used to perform prioritized normative reasoning. Meanwhile, formal argumentation provides a way to represent nonmonotonic logics. In this paper, we propose a representation of prioritized normative reasoning by argumentation. Using hierarchical abstract normative systems, we de...
Our wider research project investigates the design of a persuasive game for preventing mental health problems and improving subjective wellbeing in a student population. In this paper, we explore how persuasive game elements and interactions can be adapted to different student personalities, active stressors and attitudes. In six focus groups we in...
A Poster presented at SICSA PhD Conference 2017, University of Dundee, United Kingdom
This paper considers how persuasive messages – within the healthy eating domain – should be communicated to individuals with different personality types. Following a personality assessment, subjects imagined themselves in a scenario and evaluated the effectiveness of messages constructed using Cialdini’s principles of persuasion. Our results sugges...
We examine how persuasive messages can be used to promote and encourage healthy eating based on personality. After a personality assessment, participants assessed the persuasiveness of messages designed using Cialdini's principles of persuasion. The results of our study indicate that 'Authority' messages were most influential. In addition, we obser...
Automated planning can be used to efficiently recognize goals and plans from partial or full observed action sequences. In this paper, we propose goal recognition heuristics that rely on information from planning landmarks - facts or actions that must occur if a plan is to achieve a goal when starting from some initial state. We develop two such he...
In this paper we investigate the links between instantiated argumentation systems and the axioms for non-monotonic reasoning described in [9] with the aim of characterising the nature of argument based reasoning. In doing so, we consider two possible interpretations of the consequence relation, and describe which axioms are met by ASPIC+ under each...
Smart city approaches promise technology-based opportunities to build sustainable urban futures. However, it is unclear how current market-led approaches can contribute to achieving relevant Sustainable Development Goals (SDGs). Applying complexity science helps to develop smart city policies for urban sustainability.
Policymakers at the national a...
In this paper we propose a labelling based dialogue game for determining whether a single argument within a Dung argumentation framework is skeptically preferred. Our game consists of two phases, and determines the membership of a single argument within the extension, assuming optimal play by dialogue participants. In the first phase, one player at...
Principal Agent Theory (PAT) seeks to identify the incentives and sanctions that a consumer should apply when entering into a contract with a provider in order to maximise their own utility. However, identifying suitable contracts—maximising utility while minimising regret— is difficult, particularly when little information is available about provi...
We present an argumentation framework for reasoning within deliberation dialogues. This framework includes a dynamic notion of trust — the degree of belief placed in the dialogue participants changes over the course of the dialogue, and in turn affects the strength of the arguments the participants advance , affecting the dialogue's conclusions.
We review the First International Competition on Computational Models of Argumentation (ICCMA'15). The competition evaluated submitted solvers performance on four different computational tasks related to solving abstract argumentation frameworks. Each task evaluated solvers in ways that pushed the edge of existing performance by introducing new cha...
We demonstrate an implementation of Markov Argumentation Random Fields (MARFs), a novel formalism combining elements of formal argumentation theory and probabilistic graphical models. In doing so MARFs provide a principled technique for the merger of probabilistic graphical models and non-monotonic reasoning, supporting human reasoning in ``messy’’...
Social isolation amongst older adults represents a significant societal challenge in which persuasion offers a potential solution. To develop a persuasive interactive system for this purpose, we conducted a modelling study with carers to discover how persuasion is used to encourage social interaction amongst older adults. From an analysis of the re...
When entering a system, an agent should be aware of the obligations and prohibitions (collectively norms) that affect it. Existing solutions to this norm identification problem make use of observations of either norm compliant, or norm violating, behaviour. Thus, they assume an extreme situation where norms are typically violated, or complied with....
Market mechanisms play a key role in allocating and pricing commuters and drivers in new on-demand transport services such as Uber, and Liftago in Prague. These services successfully use different mechanisms, which suggests a need to understand the behavior of a range of mechanisms within the context of on-demand transport. In this paper, we propos...
Systems of autonomous and self-interested agents interacting to achieve individual and collective goals may exhibit undesirable or unexpected behaviour if left unconstrained. Norms have been widely proposed as a means of defining and enforcing societal constraints by using the deontic concepts of obligations, permissions and prohibitions to describ...
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...
The aim of intelligence analysis is to make sense of information that is often conflicting or incomplete, and to weigh competing hypotheses that may explain a situation. This imposes a high cognitive load on analysts, and there are few automated tools to aid them in their task. In this paper, we present an agent-based tool to help analysts in acqui...
We present a decision-theoretic approach for sampling information sources in resource-constrained environments, where there is uncertainty regarding source trustworthiness. We exploit diversity among sources to stratify the population into homogeneous subgroups to both minimise redundant sampling and mitigate the effect of source collusion. We show...
This book constitutes the refereed proceedings of the Third International Workshop on the Theory and Applications of Formal Argumentation, TAFA 2015, held in Buenos Aires, Argentina, in July 2015. The workshop was co-located with IJCAI 2015. The 15 revised full papers presented were carefully reviewed and selected from 25 submissions. The papers de...
We demonstrate CISpaces, a system for agent-aided collaborative intelligence analysis. CISpaces exploits collaboration to ease the effort of constructing hypotheses from acquired information. Argumentation-based reasoning is employed by a sensemaking agent to identify plausible hypotheses and to compute their likelihood to be justified. Information...
p>We present a decision-theoretic approach for sampling information sources in resource-constrained environments, where there is uncertainty regarding source trustworthiness. We exploit diversity among sources to stratify the population into homogeneous subgroups to both minimise redundant sampling and mitigate the effect of source collusion. We sh...
Reasoning about what is best for an agent to do in a particular situation is a challenging task. What makes it even more challenging in a dynamic environment is the existence of norms that aim to regulate a self-interested agent’s behaviour. Practical reasoning is reasoning about what to do in a given situation, particularly in the presence of conf...
When entering a system, an agent should be aware of the obligations and prohibitions (collectively norms) that will affect it. Several solutions to this norm identification problem have been proposed, which make use of observations of either other’s norm compliant, or norm violating, behaviour. These solutions fail in situations where norms are typ...
When entering a system, an agent should be aware of the obligations and prohibitions (collectively norms) that will affect it. Existing solutions to this norm identification problem make use of observations of either other's norm compliant, or norm violating, behaviour. However, they assume an extreme situation where norms are typically violated ,...
The aim of intelligence analysis is to make sense of information that is often conflicting or incomplete, and to weigh competing hypotheses that may explain a situation. This imposes a high cognitive load on analysts, and there are few automated tools to aid them in their task. In this paper, we present an agent-based tool to help analysts in acqui...
p>We present the CISpaces framework, a collaborative virtual space for intelligence analysts for the elaboration of information to explain a situation. CISpaces supports the analysis of conflicting information in collaboration exploiting argumentation schemes to structure and share analyses, crowd-sourcing to collect information and provenance to e...
Modern multiorganizational coalitions can bring diverse sets of capabilities, assets, and information sources to bear on complex and dynamic operations. However, successfully completing these operations places demands on the trust between coalition partners. When it's necessary to rely on other partners, decision makers must be able to make rapid a...
We present the CISpaces framework, a collaborative virtual space for intelligence analysts for the elaboration of information to explain a situation. CISpaces supports the analysis of conflicting information in collaboration exploiting argumentation schemes to structure and share analyses, crowd-sourcing to collect information and provenance to est...
It has been claimed that computational models of argumentation provide support for complex decision making activities in part due to the close alignment between their semantics and human intuition. In this paper we assess this claim by means of an experiment: people's evaluation of formal arguments - presented in plain English - is compared to the...
Autonomous systems suffer from opacity due to the potentially large number of sophisticated interactions among many parties and how these influence the outcomes of the systems. It is very difficult for humans to scrutinise, understand and, ultimately, work with such systems. To address this shortcoming, we developed a demonstrator which uses formal...
The work of Caminada and Amgoud presents two possible ways of satisfying the rationality postulates: one using restricted rebut, and one using unrestricted rebut. Subsequent work on ASPIC+ has extended the work of Caminada and Amgoud, for instance by allowing preferences over arguments. However, such extensions have utilised restricted rebut only....
The exchange of arguments between agents can enable the achievement of otherwise impossible goals, for example through persuading others to act in a certain way. In such a situation, the persuading argument can be seen to have a positive utility. However, arguments can also have a negative utility — uttering the argument could reveal sensitive info...
This paper describes a framework for practical reasoning in the presence of norms. We describe a formal normative model constructed using action-based alternating transition systems. This model is able to represent goals; obligations and prohibitions and their violation; and permissions, which are used to derogate the former. Inspired by Atkinson’s...
p>This paper investigates how to restrict the spread of sensitive information. This work is situated in a military context, and provides a tractable method to decide what semantic information to share, with whom, and how. The latter decision is supported by obfuscation, where a related concept or fact may be shared instead of the original. We consi...
It is often difficult for humans to understand what course of action is proposed in a plan or workflow. This is particularly the case for long plans, or plans with multiple actors. Our contributions are a) the ability to present plans as both text and graphics and b) a method of filtering and highlighting, in both modalities, which focuses the info...
In this paper we describe a decision process framework allowing an agent to
decide what information it should reveal to its neighbours within a
communication graph in order to maximise its utility. We assume that these
neighbours can pass information onto others within the graph. The inferences
made by agents receiving the messages can have a posit...
Computational trust mechanisms aim to produce trust ratings from both direct
and indirect information about agents' behaviour. Subjective Logic (SL) has
been widely adopted as the core of such systems via its fusion and discount
operators. In recent research we revisited the semantics of these operators to
explore an alternative, geometric interpre...
Norms and argumentation are two research areas which have been becoming increasingly connected over the last decade, in the legal field, in knowledge representation, ethics, or linguistics, and most recently, in agreement technologies in computer science. Norms are used to set the space of legal agreements (or commitments) and argumentation is used...
A decision procedure implemented over a computational trust mechanism aims to
allow for decisions to be made regarding whether some entity or information
should be trusted. As recognised in the literature, trust is contextual, and we
describe how such a context often translates into a confidence level which
should be used to modify an underlying tr...
This paper deals with the issue of strategic argumentation in the setting of Dung-style abstract argumentation theory. Such reasoning takes place through the use of opponent models--recursive representations of an agent's knowledge and beliefs regarding the opponent's knowledge. Using such models, we present three approaches to reasoning. The first...