Logical foundations of Smart Contracts
Kalonji Kalala
TL;DR
The work addresses the need for a formal, verifiable semantics for smart contracts operating on blockchains and cyber-physical systems. It proposes a Situation Calculus-based foundation augmented with obligation reasoning to model and verify contract behavior, extending Scherl and Levesque's frame problem solution to obligations and encoding contracts as GOLOG programs with basic contractual theories. An implementable framework and interpreter are developed to automate property verification, with alignment to the Symboleo contract specification language. The contribution offers a principled bridge between legal contract semantics and executable smart-contract models, enabling rigorous verification and analysis in decentralized settings.
Abstract
Nowadays, sophisticated domains are emerging which require appropriate formalisms to be specified accurately in order to reason about them. One such domain is constituted of smart contracts that have emerged in cyber physical systems as a way of enforcing formal agreements between components of these systems. Smart contracts self-execute to run and share business processes through blockchain, in decentralized systems, with many different participants. Legal contracts are in many cases complex documents, with a number of exceptions, and many subcontracts. The implementation of smart contracts based on legal contracts is a long and laborious task, that needs to include all actions, procedures, and the effects of actions related to the execution of the contract. An ongoing open problem in this area is to formally account for smart contracts using a uniform and somewhat universal formalism. This thesis proposes logical foundations to smart contracts using the Situation Calculus, a logic for reasoning about actions. Situation Calculus is one of the prominent logic-based artificial intelligence approaches that provides enough logical mechanism to specify and implement dynamic and complex systems such as contracts. Situation Calculus is suitable to show how worlds dynamically change. Smart contracts are going to be implement with Golog (written en Prolog), a Situation Calculus-based programming language for modeling complex and dynamic behaviors.