Defining Self-adaptive Systems: A Systematic Literature Review
Ana Petrovska, Guan Erjiage, Stefan Kugele
TL;DR
The paper tackles the absence of a widely accepted formal definition for self-adaptive systems in software and systems engineering. It conducts a systematic literature review of 1,493 papers (yielding 314 relevant studies and 9 primary formal-definitions papers) to evaluate how self-adaptive systems are formally defined and what limitations hinder broad adoption. The findings show a predominance of informal or missing definitions, with formal definitions being scarce and often lacking key aspects such as uncertainty; the authors extract lessons and propose requirements for a future unified formal definition. By outlining a structured analysis framework and identifying gaps, the work sets the groundwork for clearer terminology, better communication, and more rigorous engineering of self-adaptive systems. This foundational step can guide future research toward a widely accepted, formal understanding of self-adaptation in dynamic software and cyber-physical environments.
Abstract
In the last two decades, the popularity of self-adaptive systems in the field of software and systems engineering has drastically increased. However, despite the extensive work on self-adaptive systems, the literature still lacks a common agreement on the definition of these systems. To this day, the notion of self-adaptive systems is mainly used intuitively without a precise understanding of the terminology. Using terminology only by intuition does not suffice, especially in engineering and science, where a more rigorous definition is necessary. In this paper, we investigate the existing formal definitions of self-adaptive systems and how these systems are characterised across the literature. Additionally, we analyse and summarise the limitations of the existing formal definitions in order to understand why none of the existing formal definitions is used more broadly by the community. To achieve this, we have conducted a systematic literature review in which we have analysed over 1400 papers related to self-adaptive systems. Concretely, from an initial pool of 1493 papers, we have selected 314 relevant papers, which resulted in nine primary studies whose primary objective was to define self-adaptive systems formally. Our systematic review reveals that although there has been an increasing interest in self-adaptive systems over the years, there is a scarcity of efforts to define these systems formally. Finally, as part of this paper, based on the analysed primary studies, we also elicit requirements and set a foundation for a potential (formal) definition in the future that is accepted by the community on a broader range.