Abstract—The field of evolutionary robotics has demonstrated the ability to automatically design the morphology and controller of simple physical robots through synthetic evolutionary processes. However, it is not clear if variation-based search processes can attain the complexity of design necessary for practical engineering of robots. Here, we demonstrate an automatic design system that produces complex robots by exploiting the principles of regularity, modularity, hierarchy, and reuse. These techniques are already established principles of scaling in engineering design and have been observed in nature, but have not been broadly used in artificial evolution. We gain these advantages through the use of a generative representation, which combines a programmatic representation with an algorithmic process that compiles the representation into a detailed construction plan. This approach is shown to have two benefits: it can reuse components in regular and hierarchical ways, providing a systematic way to create more complex modules from simpler ones; and the evolved representations can capture intrinsic properties of the design space, so that variations in the representations move through the design space more effectively than equivalent-sized changes in a nongenerative representation. Using this system, we demonstrate for the first time the evolution and construction of modular, three-dimensional, physically locomoting robots, comprising many more components than previous work on body-brain evolution. Index Terms—Design automation, evolutionary robotics, generative representations. I.

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Abstract. The use of subprocesses in large process models is an important step in modeling practice to handle complexity. While there are several advantages attributed to such a modular design, including ease of reuse, scalability, and enhanced understanding, the lack of precise guidelines turns out to be a major impediment for applying modularity in a systematic way. In this paper we approach this area of research from a critical perspective. Our first contribution is a review of existing approaches to process model modularity. This review shows that aside from some limited insights, a systematic and grounded approach to finding the optimal modularization of a process model is missing. Therefore, we turned to modular process models from practice to study their merits. In particular, we set up an experiment involving professional process modelers and tested the effect of modularization on understanding. Our second contribution, stemming from this experiment, is that modularity appears to pay off. We discuss some of the limitations of our research and implications for future design-oriented approaches. 1

transactions, and the boundaries of firms

We examine the evolution of vertical specialization in three industries: chemicals, computers, and semiconductors. Vertical specialization is the restructuring of industry-wide value chains, such that different stages of the development, production, and marketing processes are controlled by different firms, rather than being vertically integrated within the boundaries of individual firms. In some cases, vertical specialization may span international boundaries and is associated with complex international production networks. After decades of vertical specialization, firms in the chemical industry appears to be re-integrating stages of the value chain. By contrast, the semiconductor and computer industries have experienced significant vertical specialization during the past ten years. We examine how and why these contrasting trends in vertical specialization have coevolved with industry maturation and decline, and underscore the importance and role of both industry factors and business strategies necessary for industries to become more specialized. We also consider the effects of vertical specialization on the sources of innovation and the geographic redistribution of production and other activities. We conclude that the evolution of vertical specialization in these three industries has both reflected and influenced the strategies of leading firms, while also displaying industry- specific characteristics that are rooted in their different technological and market characteristics.

Free and open source software has had a major impact on the computer industry since the late 1990s and has changed the way software is perceived, developed and deployed in many areas. Free and open source software, or FOSS, is typically developed in a collaborative fashion and the majority of contributors are volunteers. Even though this collaborative form of develop-ment has produced a significant body of software, the development process is often described as unstructured and unorganized. This dissertation studies the FOSS phenomenon from a quality perspective and investigates where im-provements to the development process are possible. In particular, the focus is on release management since this is concerned with the delivery of a high quality product to end-users. This research has identified considerable interest amongst the FOSS commu-nity in a novel release management strategy, time based releases. In contrast to traditional development which is feature-driven, time based releases use time rather than features as the criterion for the creation of a new release. Releases

Editor’s Introduction pp. 004- 005

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The idea of congruence between the structure of technical and work dependencies has been demonstrated in commercial software development but has not been explored in detail in free and open source software (FLOSS) development. Previous work identified 103 task episodes, selected from two FLOSS projects, and found that 83 were performed by single actors. We analyze the 20 tasks with multiple actors and find that 14 were performed in the absense of any discursive communication between developers. The qualitative analysis of this evidence shows the paradox that, even if the developers do not seem to communicate explicitly, the software is nonetheless built as result of a collective effort, apparently without central coordination. In answer to this puzzle, this paper turns to the concept of stygmergic coordination as possible explanation. Stigmergy explains how actors can affect the behavior of other members of the community through the traces that their activities leave in shared artifacts. Such collaboration has implications for the socio-technical congruence analysis and the design of collaborative systems. 1.

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