Jan Odelstad

Normative positions within an algebraic approach to normative systems

The formal analysis of normative systems as initiated by Alchourron and Bulygin can be complemented by the analysis of normative positions as pursued by Kanger, Lindahl, Sergot and Jones. The paper ...

Algebras for Agent Norm-Regulation

An abstract architecture for idealized multi-agent systems whose behaviour is regulated by normative systems is developed and discussed. Agent choices are determined partially by the preference ordering of possible states and partially by normative considerations: The agent chooses that act which leads to the best outcome of all permissible actions. If an action is non-permissible depends on if the result of performing that action leads to a state satisfying a condition which is forbidden, according to the norms regulating the multi-agent system. This idea is formalized by defining set-theoretic predicates characterizing multi-agent systems. The definition of the predicate uses decision theory, the Kanger–Lindahl theory of normative positions, and an algebraic representation of normative systems.

Intermediaries and intervenients in normative systems

Many concepts in legal texts are “intermediaries”, in the sense that they serve as links between statements of legal grounds, on one hand, and of legal consequences, on the other. In our paper, an ...

Normative systems and their revision: an algebraic approach

The paper discusses normative systems and their revision within an algebraic framework. If a system is logically well-formed, certain norms, called connecting norms, determine the system as a whole. It is maintained that, if the system is well-formed, a relation “at least as low as” determines a lattice or quasi-lattice of its connecting norms. The ideas are presented mainly in the form of comments on a legal example concerning acquisition of movable property by extinction of another persons previous rights.

Intermediate concepts in normative systems

In legal theory, a well-known idea is that an intermediate concept like “ownership” joins a set of legal consequences to a set of legal grounds. In our paper, we attempt to make the idea of a joining between grounds and consequences more precise by using an algebraic representation of normative systems earlier developed by the authors. In the first main part, the idea of intermediate concepts is presented and earlier discussions of the subjects are outlined. Subsequently, in the second main part, we introduce a more rigorous framework and develop the formal theory. In the third part, the formal framework is applied to examples and some remarks on a methodology of intermediate concepts are given.

jDALMAS: A Java/Prolog Framework for Deontic Action-Logic Multi-Agent Systems

A norm-regulated Deontic Action-Logic Multi-Agent System (DALMAS) is regulated by a normative system consisting of norms, which are expressed in an algebraic notation based on the Kanger-Lindahl theory of normative positions. A general-level Prolog implementation of the abstract DALMAS architecture makes it possible to implement specific systems in Prolog. This work describes jDALMAS, a Java library that may be used to create DALMAS applications in Java. A jDALMAS application has a client/server architecture, where a Prolog implementation of a specific system acts as a logic server. Together, the general-level Prolog implementation and the jDALMAS packages offer a framework for implementation of specific systems. Two examples of such implementations are presented here.

Stratification of normative systems with intermediaries

Abstract Writing a contract with a specific content is a ground for purchase, purchase is a ground for ownership, ownership is a ground for power to dispose. Also power to dispose is a consequence of ownership, ownership is a consequence of purchase, etc. The paper presents a continuation of the authorsʼ previous work on the algebraic representation of ground-consequence chains in normative systems. The paper analyzes different kinds of “implicative closeness” between grounds and consequences in chains of legal concepts, in particular combinations of “weakest ground”, “strongest consequence” and “minimal joining”. The idea of a conceptʼs being intermediate between concepts of two different sorts is captured by the technical notion of “intervenient”, defined in terms of weakest ground and strongest consequence. Lattice theory is used for studying the links between different strata and the structure of intervenient strata. We focus on (1) intervenient minimality, (2) conjunctions and disjunctions of intervenients, (3) organic wholes of intervenients, and (4) a typology of different kinds of intervenients. Also (5), we pay attention to the properties of intervenients in a network of “strata”. A legal example concerning grounds and consequences of “ownership” and “trust” is used to illustrate the application of the formal theory.