A Formal Language for Electronic Contracts

Abstract

In this paper we propose a formal language for writing electronic contracts, based on the deontic notions of obligation, permission, and prohibition. We take an ought-to-do approach, where deontic operators are applied to actions instead of state-of-affairs. We propose an extension of the μ-calculus in order to capture the intuitive meaning of the deontic notions and to express concurrent actions. We provide a translation of the contract language into the logic, the semantics of which faithfully captures the meaning of obligation, permission and prohibition. We also show how our language captures most of the intuitive desirable properties of electronic contracts, as well as how it avoids most of the classical paradoxes of deontic logic. We finally show its applicability on a contract example.

Challenges in the Specification of Full Contracts

“…These include introspection, real-time issues, crossreferences, a suitable treatment of true concurrency, fairness and conditional contracts Also, since we have considered an ought-to-do approach (i.e. the deontic modalities are applied on actions and not state-of-affairs), one may also have to consider many aspects from dynamic logic, in the spirit of Meyer's work [21] (see also [4,26]). …”

“…A choice operator explicitly appears in those works using the ought-to-do approach, where the operator is among actions (a + b), for instance in the works by Broersen et al [4], and Prisacariu and Schneider [26]. The latter also allowing concurrent actions.…”

“…Languages such as CL [26] use the LTL-and CTL-style until operator. In this paper, we use the regular expression-style star operator to indicate repetitions.…”

“…In the latter this introduces a big challenge concerning the semantic interpretation of & in a deontic logic based on actions in the style of dynamic logic, since conjunction is usually interpreted as a branching in certain cases. See [27] for further discussion on the topic.…”

“…See for instance [26] for an example on the formalisation of a legal contract, and [10,7] for a justification on the use of deontic logic, and examples, on fault-tolerant systems. See [14,16] for compensable transactions, [11] for regulatory conformance checking, and [24] for state of the art and challenges in SOA.…”