Computing Strong and Weak Permissions in Defeasible Logic

Abstract

In this paper we propose an extension of Defeasible Logic to represent and compute three concepts of defeasible permission. In particular, we discuss different types of explicit permissive norms that work as exceptions to opposite obligations. Moreover, we show how strong permissions can be represented both with, and without introducing a new consequence relation for inferring conclusions from explicit permissive norms. Finally, we illustrate how a preference operator applicable to contrary-to-duty obligations can be combined with a new operator representing ordered sequences of strong permissions which derogate from prohibitions. The logical system is studied from a computational standpoint and is shown to have liner computational complexity

Towards Legal Compliance by Correlating Standards and Laws with a Semi-automated Methodology

“…Input/output logic is not the only deontic framework that is not based on possible-world semantics; alternatives are imperative logic [16], prioritized default logic [21] and defeasible deontic logic [14]. A fine-grained comparison between the mentioned formalisms on the basis of norm-based semantics goes beyond the scope of this paper, in that it mostly lies on a theoretical level.…”

Resource-bounded Norm Monitoring In Multi-agent Systems

“…In this paper we also take this assumption as it is consistent with socio-technical systems. However, legal and regulatory domains are usually more complex (i.e., norm specifications are dynamic and formed by several normative systems), which has led to interesting questions as the need for weak (implicit or default) permissions and strong (explicit) permissions (Alchourrón & Bulygin, 1981), norm dynamics (Alchourrón & Bulygin, 1971) and defeasible logics (Governatori, Olivieri, Rotolo, & Scannapieco, 2013).…”

Logic and Games for Ethical Agents in Normative Multi-agent Systems

“…We conjecture that if we restrict every formula that appears in I/O logic to be a conjunction of literals, then all decision problems studied in this paper is tractable. Such restricted prioritized I/O logic has similar expressive power to the logic of abstract normative systems [7], as well as defeasible deontic logic [9]. A detailed comparison between these logic is also left as future work.…”