A Game of Attribute Decomposition for Software Architecture Design

Attribute-driven software architecture design aims to provide decision support by taking into account the quality attributes of softwares. A central question in this process is: What architecture design best fulfills the desirable software requirements? To answer this question, a system designer needs to make tradeoffs among several potentially conflicting quality attributes. Such decisions are normally ad-hoc and rely heavily on experiences. We propose a mathematical approach to tackle this problem. Game theory naturally provides the basic language: Players represent requirements, and strategies involve setting up coalitions among the players. In this way we propose a novel model, called decomposition game, for attribute-driven design. We present its solution concept based on the notion of cohesion and expansion-freedom and prove that a solution always exists. We then investigate the computational complexity of obtaining a solution. The game model and the algorithms may serve as a general framework for providing useful guidance for software architecture design. We present our results through running examples and a case study on a real-life software project.Comment: 23 pages, 5 figures, a shorter version to appear at 12th International Colloquium on Theoretical Aspects of Computing (ICTAC 2015

The importance of the observer in science

The concept of {\em complexity} (as a quantity) has been plagued by numerous contradictory and confusing definitions. By explicitly recognising a role for the observer of a system, an observer that attaches meaning to data about the system, these contradictions can be resolved, and the numerous complexity measures that have been proposed can be seen as cases where different observers are relevant, and/or being proxy measures that loosely scale with complexity, but are easy to compute from the available data. Much of the epistemic confusion in the subject can be squarely placed at science's tradition of removing the observer from the description in order to guarantee {\em objectivity}. Explicitly acknowledging the role of the observer helps untangle other confused subject areas. {\em Emergence} is a topic about which much ink has been spilt, but it can be understand easily as an irreducibility between description space and meaning space. Quantum Mechanics can also be understood as a theory of observation. The success in explaining quantum mechanics, leads one to conjecture that all of physics may be reducible to properties of the observer. And indeed, what are the necessary (as opposed to contingent) properties of an observer? This requires a full theory of consciousness, from which we are a long way from obtaining. However where progress does appear to have been made, e.g. Daniel Dennett's {\em Consciousness Explained}, a recurring theme of self-observation is a crucial ingredient.Comment: In Proceedings The Two Cultures: Reconsidering the division between the Sciences and Humanities, UNSW, July 200