Andrew J. I. Jones

A Formal Characterisation of Institutionalised Power

It is a standard feature of norm-governed institutions that designated agents are empowered to create particular kinds of states of aaairs by means of the performance of speciied types of actions. Frequently, the states of affairs are of a normative kind, in the sense that they pertain to rights and obligations, as for instance when a Head of Department signs a purchase agreement and thereby creates an obligation on his employer to pay for goods received. We use the term institutionalised power to stand for the notion of power we here seek to explicate. Following a lead from jurispru-dential discussions of legal power, we distinguish institutionalised power from permission and practical possibility. We deene a conditional connective intended to capture the consequence relation implicit in statements of the form: according to the constraints operative in institution s, the performance of some act A by agent x counts as a means of creating state of aaairs B. When combined with deontic and action logics, the new connective facilitates the analysis of a number of notions crucial to the understanding of organised interaction in institutions, such as authorisation and delegation. We conclude with some illustrations of the expressive power of the new logical language.

Deontic Logic and Contrary-to-Duties

Deontic logic is concerned with the logical analysis of such normative notions as obligation, permission, right and prohibition. Although its origins lie in systematic legal and moral philosophy, deontic logic has begun to attract the interest of researchers in other areas, particularly computer science, management science and organisation theory. Among the application areas which have already received some attention in the literature are: issues of knowledge representation in the design of legal expert systems; the formal specification of aspects of computer systems, for instance in regard to security and access control policies, fault tolerance, and database integrity constraints; the formal characterisation of aspects of organisational structure, pertaining for example to the responsibilities and powers which agents are required or authorised to exercise. The “AEON” workshop proceedings provide some illustrations of work in these areas (see [ΔEON91; ΔEON94; ΔEON96]).

On Normative-Informational Positions

This paper is a preliminary investigation into the application of the formal-logical theory of normative positions to the characterisation of normative-informational positions, pertaining to rules that are meant to regulate the supply of information.

Family-based analysis using a dense single-nucleotide polymorphism-based map defines genetic variation at PSORS1, the major psoriasis-susceptibility locus

Psoriasis is a common skin disorder of multifactorial origin. Genomewide scans for disease susceptibility have repeatedly demonstrated the existence of a major locus, PSORS1 (psoriasis susceptibility 1), contained within the major histocompatibility complex (MHC), on chromosome 6p21. Subsequent refinement studies have highlighted linkage disequilibrium (LD) with psoriasis, along a 150-kb segment that includes at least three candidate genes (encoding human leukocyte antigen-C [HLA-C], alpha-helix-coiled-coil-rod homologue, and corneodesmosin), each of which has been shown to harbor disease-associated alleles. However, the boundaries of the minimal PSORS1 region remain poorly defined. Moreover, interpretations of allelic association with psoriasis are compounded by limited insight of LD conservation within MHC class I interval. To address these issues, we have pursued a high-resolution genetic characterization of the PSORS1 locus. We resequenced genomic segments along a 220-kb region at chromosome 6p21 and identified a total of 119 high-frequency SNPs. Using 59 SNPs (18 coding and 41 noncoding SNPs) whose position was representative of the overall marker distribution, we genotyped a data set of 171 independently ascertained parent-affected offspring trios. Family-based association analysis of this cohort highlighted two SNPs (n.7 and n.9) respectively lying 7 and 4 kb proximal to HLA-C. These markers generated highly significant evidence of disease association (P<10-9), several orders of magnitude greater than the observed significance displayed by any other SNP that has previously been associated with disease susceptibility. This observation was replicated in a Gujarati Indian case/control data set. Haplotype-based analysis detected overtransmission of a cluster of chromosomes, which probably originated by ancestral mutation of a common disease-bearing haplotype. The only markers exclusive to the overtransmitted chromosomes are SNPs n.7 and n.9, which define a 10-kb PSORS1 core risk haplotype. These data demonstrate the power of SNP haplotype-based association analyses and provide high-resolution dissection of genetic variation across the PSORS1 interval, the major susceptibility locus for psoriasis.

Action concepts for describing organised interaction

The main aim of this paper is to propose a set of action concepts useful for describing organised interaction. These action concepts focus on two distinctions: the distinction between direct and indirect action, and the distinction between successful and not necessarily successful action. The formal characterisation of these concepts is given by means of modal logic, following the same tradition in the logical characterisation of act descriptions as employed by Kanger (1972) and Porn (1970). The modal action operators proposed are also combined with a deontic logic and a conditional logic, in order to illustrate their application to the analysis of some simple organisations. The focus of interest is on the notion of transmission of agency, and on the characterisation of the conditions under which an organisation recognises that an agent has fulfilled the responsibilities assigned to him.

Formal Specification of Security Requirements using the Theory of Normative Positions

We use a number of the examples presented in [Ting 1990] to illustrate how the formal theory of normative positions may serve as a tool for clarifying, and making precise, the specification of security requirements, particularly in regard to access control. We describe the basic features of the theory of normative positions (which has its roots in the analytical theory of law), and of the modal logics (deontic and action logics) involved in its formulation. We then indicate three levels of software we have under development, which aim to turn the analytical procedures into a practical tool. Our concluding remarks relate our discussion of Tings examples to some particular issues in the formal specification of computer systems.

Research directions in agent communication

Increasingly, software engineering involves open systems consisting of autonomous and heterogeneous participants or agents who carry out loosely coupled interactions. Accordingly, understanding and specifying communications among agents is a key concern. A focus on ways to formalize meaning distinguishes agent communication from traditional distributed computing: meaning provides a basis for flexible interactions and compliance checking. Over the years, a number of approaches have emerged with some essential and some irrelevant distinctions drawn among them. As agent abstractions gain increasing traction in the software engineering of open systems, it is important to resolve the irrelevant and highlight the essential distinctions, so that future research can be focused in the most productive directions. This article is an outcome of extensive discussions among agent communication researchers, aimed at taking stock of the field and at developing, criticizing, and refining their positions on specific approaches and future challenges. This article serves some important purposes, including identifying (1) points of broad consensus; (2) points where substantive differences remain; and (3) interesting directions of future work.

Conventional Signalling Acts and Conversation

This article aims to provide foundations for a new approach to Agent Communication Languages (ACLs). First, we outline the theory of signalling acts. In contrast to current approaches to communication, this account is neither intention-based nor commitment-based, but convention-based. Next, we outline one way of embedding that theory within an account of conversation. We move here from an account of the basic types of communicative act (the statics of communication) to an account of their role in sequences of exchanges in communicative interaction (the dynamics of communication). Finally, we apply the framework to the analysis of a conversational protocol.

On the characterisation of a trusting agent - aspects of a formal approach

The rapid increase in the use of open distributed systems has given rise to a number of important issues for computer scientists, some of which concern the organisation of interactions between computers, between humans, and between humans and computers. For instance, such interactions are the focus of attention in access control policies (Abadi et al., 1993), and in cryptographic protocols (Burrows et al., 1990), both of which specify the actions that are to be performed by the participating agents.

The design of intelligent socio-technical systems

The design of intelligent socio-technical systems calls for careful examination of relevant social and organizational concepts. We present a method for supporting this design process, placing emphasis on different levels of formal characterization, with equal attention to both the analysis of concepts in a formal calculus independent of computational concerns, and the representation of concepts in a machine-processable form, fully cognizant of implementation issues—a step in the method we refer to as principled operationalization. There are many tools (i.e. formal languages) that can be used to support the design method; we define and discuss criteria for evaluating such tools. We believe that, were the method proposed to be adopted, it would enhance the state-of-the-art in the systematic design and engineering of socio-technical systems, respecting the fundamentally interdisciplinary nature of those tasks, in both their theoretical and practical dimensions.