History - “Science of Design” “design” is at a point like medicine and law in 19th century? transformation of engineering from vocational practice to applied science WWII entry of “systems theory” –emergence becomes a topic emergence - cannot predict behavior of new combinations of “known” elements

What do Designers Do? transform a current world into a more desirable one –use descriptive principles history has brought us deep specialization? –produce normative results what “design” is all about “systems” context for customers (dual to specialization?) how do we actually get beyond the current state of the art? –“design” itself is not “owned” by any specialization - it is about social needs (?) the task of joining function, form, methodology, and context (Taylor)

Other Opinions on Design Cross, reporting on a number of studies in design, argues that design is quite different from science. While scientists focus on the problem, on discovering the rule that is operating, designers focus on the solution, on achieving the desired result. –He concludes that design is ultimately a series of personal choices based on a sense of what is "right." A design process provides a framework in which the decisions can be made (Rowland) The decisions made during the design process involve a balancing act among these four components: –Goals –Resources, which are the materials3⁄4 both physical and intellectual3⁄4 available to present information. – Design techniques, which are the strategies for achieving the goals using the resources available. – Constraints, which are outside influences that limit the use of resources and strategies to achieve a goal (Carliner, 1995).

Brian Marick on Science of Design My position is that one Science of Design should be a science of people doing design... more akin to anthropology or social studies of scientific practice than to physics... A successful research program would win the Jolt software productivity award as well as help someone gain tenure.

Michael Jackson on Design Science Problem world for software is likely heterogeneous Our Specs rely on different assumptions about problem world properties –possibly conflicting assumptions? Software Structure must impl. some approx to the conjunction of the indiv. software specs –while ensuring most critical functionality is most reliable

Jackson Normal design –standard forms to meet standard needs experience, social training, or objective? Radical design –delivers new product forms to meet new demands immaturity of software (lack of experience,..) versatility of computers (general purpose machine is “new” to humanity)

Jackson Science of software design: –explicate properties of decomp and composition –investigate reqts, specs and assumptions about problem worlds and software components –support appropriate tradeoff anaylsis My question - –is this about design of “software” or design of products via software or….using software

John Knight weighs in Interplay between software design and system design 1.software be viewed as system component –subject to all influences that affect system design 2.software itself must affect system design –if software is to provide system safety services –must be shown to function correctly in ANY feasible system state –overall safety goals of the system have to be shown to be met with all practical limitations inherent in any software development

Walt Scacchi Open source the very best road to study design iterative development incremental release peer review –continuous distributed testing and profiling community building –standards –information exposure (vs. information hiding)

Some Views of “Design” “devising courses of action aimed at changing existing situations into preferred ones” (Simon) “initiating change in man-made things” (Jones) “the process of inventing physical things which display new physical order, organization, form, in response to function” (Alexander) “a reflective conversation with the materials of a design situation” (Schon) “creating complex sociotechnical systems that help workers adapt to the changing and uncertain demands of their job” (Rasmussen)

Simon’s Topics in “Design Science” A Theory of evaluation Computational methods Formal logic of design Search mechanisms Representation theory

Theory of Evaluation To go beyond the state of the art –a constructive task but not ad-hoc? –create a search-space of alternatives we WANT constraints –(not the usual response) –need a theory of utility a situated theory –need statistical decision theory to give us our “satisficing” decisions

Computational Methods How to find “optimal” alternatives? –linear programming –control theory –dynamic programming How to find satisficing alternatives? –algorithms and heuristics for satisficing

Formal Logic of Design and Search Mechanisms Design alternatives must be synthesized Logic of search –what path should I try next? search for sufficient, not necessary actions for attaining goals –“generator-test” cycle - create the alternatives variety in solution space may be desirable in itself: the process might be important too –for the knowledge it generates »an “evolutionary” process involving a satisficing utility function?

Theory of Representation Problem: design of complex artifacts –requires skills of diverse “designers” satellite example - software engineers, materials engineers, power engineers, lawyers, network engineers, marketers… bounded rationality “symmetry of ignorance” (Rittel): –knowledge of each is needed (separate knowledge) –each is ignorant of what the other has to contribute (common to all)

Think: Representation of Problems in Design Space For mathematics, a “solution” is a transformation in representation of the problem. (Simon) – the software process ? Notations for expressing design? –DfDfA (Young) consider programming languages –develop techniques to detect errors –develop notations to make the error idiom less likely –develop notations to make the particular error unexpressable »analysis is replaced by synthesis! –what are the underlying principles at work?

Design and Life Fragmentation (specialization) of disciplines –science and non-science –science and engineering and liberal arts … BUT, “design” as a commonality? –music is possibly oldest of sciences of artificial (design) formal pattern important contacts with inner environment outer environment - problems of composition as “design” –search for alternatives, evaluation –“rules of thumb” –representation problems

Breadth of “design” as an activity Is it nearly universal? –problem solving in general Can a musician speak with a physician and a software engineer about the “design” activity? –I have experienced this, have you?

Software My old definition: “the static representation of a dynamic process to be instantiated to satisfy a human need” Simon says that “designers of design processes” –have had to be explicit as never before about what is involved in creating a design and what takes place when the creation is going on.

Software do we agree on this as a good abstraction descriptive of what we do in software engineering? designing static processes to be instantiated as a dynamic process (at run time) in order to solve another design problem who has done similar things before? –lawyers? urban planners? is there a good analogy to negligence law?