||Letting go is hard to do. Remember back to when, after months of trying, you let go of the handlebars of your bicycle and sailed down the street, effortless and assured. It was a freedom born of mastery, balance and technique. You had let go, but were in control. Technique extends to other devices as well and we are here to discuss architectural computation. Here too, as we will see, mastery is shown by letting go. These papers explore new degrees of freedom in design computation. Each is on a separate aspect of architecture, whether it be aesthetics, process, or structure. Two papers inquire into the entities of design and the processes by which they are manifested. They pose important questions. If we can affect the course of design going forward, are we free to change its past? By defining the characteristics of objects at the outset, are we through automation free to choose from a refined spectrum of outcomes? From the evidence of these papers, the answer to both questions is yes. Through the agency of parametric design we can affect the future and past of architectural processes and their products. Rather than being locked into rigid, linear decisions we are temporally free to choose, tweak and modify. Choice and chance play an important role in aesthetics as well. This has become emblematic of design trends as we have seen in recent years. One of our papers addresses the indeterminacy of particle systems in the design of a monument to the victims of 9/11. By letting go of the handlebars of the computer, the author has been freed to new, poetic forms and processes. Another paper opens urban design to its client community by use of a sophisticated web site. In the tradition of populist innovators like Charles Moore and Lucien Kroll, the authors have extended the design process beyond the office walls to the city itself. The designers, by loosening their grip on the project have made the effort democratic and participatory. Intriguingly, at the end of the paper, they note that this use of cyberspace opens the door to a non-physical architecture. Could architecture, then, let go its materialist biases as well? We hope to engage this and other questions shortly.We are pleased then, to share with you these insights and projects. Wassim and I hope that these presentations will be as liberating for you as they were for us.