Ultra-Large-scale Systems (ULSS) This paper recommends ten design principles and five design practices for ULS systems, drawing on known systems engineering practice and an understanding of how complexity science is applied in other domains. The paper offers practitioners a strategy and a practical approach to deal with ULS systems -or indeed any system that is larger scale and more complex than those they are accustomed to dealing with -and shows academics some possible routes to addressing the research challenges set out in the SEI report on ULS systems. are a major new challenge for systems and software engineering. Current engineering practice is ahead of the science -we are building systems we do not know how to characterise or analyse, and whose behaviour we cannot fully predict. ULS are characterised by complexity, dominated by emergence, and exist in a state of constant reconfiguration and evolution; all of which make untenable a reductionist approach to engineering and a "closed system" approach to specification and certification.Sillitto et al, 2006 -Engineering NEC -Basic Principles, MOD Integration Authority,

Over the past decades, a common definition of the term system has eluded researchers and practitioners alike. We reviewed over 100 current and historical definitions of system in an effort to understand perspectives and to propose the most comprehensive definition of this term. There is much common ground in different families of definition of system, but there are also important and significant differences. Some stem from different belief systems and worldviews, while others are due to a pragmatic desire to establish a clear definition for system within a particular community, disregarding wider considerations. In either case, it limits the effectiveness of various system communities' efforts to communicate, collaborate, and learn from the experience of other communities. We discovered that by considering a wide typology of systems, Bertalanffy's General Systems Theory provides a basis for a general, self‐consistent sensible framework, capable of accommodating and showing the relationships amongst the variety of different definitions of and belief systems pertaining to system. Emergence, the appearance of a new phenomenon or capability as a result of relation or interaction between objects, is key in differentiating between objects that are systems and those that are not. Hence we propose a family of definitions, related by the common theme of emergence, which is in line with both the realist and constructivist worldviews, and covers real and conceptual systems. We believe this better reflects the current scope of systems engineering and is required to support the aspirations expressed in INCOSE SE Vision 2025.

Over the past decades, the definition of system has eluded researchers and practitioners. We reviewed over 100 definitions of system to understand the variations and establish a framework for a widely acceptable system definition or a family of system definitions. There is much common ground in different families of definitions of system, but there are also important and significant ontological differences. Some differences stem from the variety of belief systems and worldviews, while others have risen within particular communities. Both limit the effectiveness of system communities’ efforts to communicate, collaborate, and learn from others’ experience. We consider three ontological elements: (1) a worldview‐based framework for typology of different system types and categories, (2) key system concepts that are fundamental to the various system types and categories, and (3) appropriate language for the target audience. In this work, we establish the ontological framework, list key concepts associated with different types of system, and point to a direction for agreeing on an integrated set of system definitions in a neutral language consistent with the framework. The definitions are compatible with both the realist and constructivist worldviews, covering real (physical, concrete) and conceptual (abstract, logical, informatical) systems, which are both human‐made (artificial) and naturally occurring, using language acceptable to a wide target stakeholder audience. The contribution of this paper is setting up an ontologically founded framework of system typologies, providing definitions for system, and identifying the issues involved in achieving a widely accepted definition or family of definitions of system.

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ISO's process to adopt the IEEE 1471 standard on architecture descriptions has revealed of the order of 130 standards concerning or relating to architectures and architecting. Within the “enterprise architecture” theme alone, different people use the term to refer to mean quite different things: the “architecture of the enterprise as a system”; the enterprise context for the enterprise IT system; or the architecture of the enterprise IT system itself. A focus on tools and methods has led to confusion between the creative activity of “architecting”, by which I mean making or exposing the key strategic decisions about the purpose, organisation, behaviour and critical design features of the system, and the analytical and descriptive activity of architecture modelling, which supports and captures the results of architecting. The INCOSE UK Architecture Working Group established a “belief systems” methodology to explore and seek to reconcile the many conflicting views on architecting This paper expands on the views presented by the author at the IS08 Architecture panel session in an effort to identify and communicate a better understanding of the fundamental skills, principles, philosophy and approach underpinning effective systems architecting. It seeks to improve their integration by focusing on “purpose, context and process” of architecting with the perspective that “hard systems exist inside soft systems”, and to show that “lean pull” allows architecting to focus on the intended use of its products rather than adherence to process standard or frameworks.