A non-monotonic logic of institutional agency is defined combining a computationally oriented nonmonotonic system (Defeasible Logic) and intensional notions of agency.

In this paper we show that the Hilbert system of agency and ability presented by Dag Elgesem is incomplete with respect to the intended semantics. We argue that completeness result may be easily regained. Finally, we shortly discuss some issues related to the philosophical intuition behind his approach. This is done by examining Elgesem’s modal logic of agency and ability using semantics with different flavours. 1

Abstract. In an organizational context the norms that apply to an agent depend on the roles he holds in the organization. The deontic characterization of structural roles is defined when the organization is created. But an organization is not a static entity. Among the dynamic phenomena that occur in an organization there are interactions between agents consisting in a transference of obligations or permissions from an agent to another. These kind of interactions are called delegation. In this paper we analyze different ways in which delegation occurs in an organizational context. We argue that the concept of “agent in a role ” is relevant to understand delegation. A deontic and action modal logic is used to specify this concept. 1

Semiotics is the formal doctrine of signs. Organizational Semiotics is a particular branch of Semiotics, concerned with understanding organizations as information systems. Information Systems ’ core concepts such as information and communication are very complex and ill-defined concepts, which should be analyzed in terms of more elementary notions such as semiotic signs. Business processes would then be seen as processes involving the creation, exchange and use of signs. Rejecting the existence of a totally objective reality, we adopt as our philosophical stance a radical relativistic model. In this model both human agents and artificial agents have a constructed knowledge about reality, which requires the agent active participation, and all knowledge is connected to a knowing agent. In this view, organizational activity becomes an information process based on the notion of responsible agent, and we propose a model that accommodates both the social dimension in organizational agents behavior and the relative autonomy that individual agents exhibit in organizations. The EDA (Epistemic-Deontic-Axiological) model, here proposed, enables the representation of agent informational states and simultaneously defines the conceptual communication framework. Agents use their knowledge (epistemic level) and take into account their obligations and authorizations (deontic level), which they may choose to accept or to violate, to decide what to do next, i.e. to define their goals. In the process they

this paper. Elgesem's semantics for the modal logic of agency and ability is a structure f 1 , . . . , f n ,V (cf. [7, p. 20] and [6, p. 54]), where each f i , 1 n is a function as in the structure described above and i is an agent. Since there are no interactions among the agents and all functions f are independent from each other and obey the same conditions, we can restrict ourselves to the case of a single agent. Elgesem also considers some foundational aspects of the notions he deals with and introduces some additional functions in order to capture the idea of avoidability and accidence. However those functions do not play any relevant role in the characterisation of the modal operators E and C. The valuation function and the constraints on the model are given in terms of properties of f . The other functions are used to specify constraints on concrete instances of f . Finally V is a valuation function while v is an assignment. S1. w # E p iff w v(p); S2. w # E iff w E A; S3. w # E A B iff w E A or w # E B; S4. w # E EA iff w , w); S5. w # E CA iff f (#A# / 0

In [3, 4] the present authors and colleagues have provided a model of organisations of agents in terms of policy-based normative systems. An organisation is thus characterised by specifying the normative positions relevant to design its structure. This abstract summarises further results in this direction 1. In particular, the research provides a computational framework based on Defeasible Logic to capture some theoretical intuitions developed in [3, 4]. The focus is on the idea of institutionalised power, as represented by the counts-as link, and on two aspects of agency: the notions of attempt and of personal and direct action to realise states of affairs. For the first issue, we adopted the approach of [3, 4], inspired, with some differences, by [5, 6]. For the second aspect, the reference is to recent developments of the Kanger-Lindahl-Pörn theory of action [7, 8, 6]. The model embeds also the modal operator proc, which represents the act of proclaiming to capture some minimal properties of all speech acts that are intended to modify the institutional world [3, 4]. The goal of the research is computational insofar as it proposes an efficient and flexible formalism to deal with counts-as conditionals and their interplay with agency. In fact, [4, 3], but also [5, 6], can hardly be used directly for implementation since they are based on conditional logics. On the other hand, this research aims