# Revisiting Problem-Solution Co-Evolution in the Context of Team Conceptual Design Activity
## 1 Introduction
**_Evaluation is most probable to be followed by synthesis during team conceptual design activity._  
In addition to the assumptions stemming from the prescriptive viewpoint of design as solving well-defined problems, two additional hypotheses can be posed based on the descriptive perspective of design as co-evolution of the ill-defined problem and the design solutions. According to [PERSON] et al. [22; 23], the conventional problem-solving process can be characterised as a design search, where the set of requirements is well-defined and fixed prior to the search for solutions. Such a process typically follows the prescribed A-S-E sequence, as described in the above-listed assumptions. The search becomes exploration when different parts of the solution space are searched, or space itself is expanded due to changes in the set of problem entities. The result of exploration is not only a solution but also a well-defined problem [22]. In co-evolutionary design, the exploration also spreads to the problem space and implies mutual interaction between the design problem and the solution alternatives, instead of just the continuous refinement of solutions [21; 23]. Consequently, the co-evolution perspective proposes that, in the case of ill-defined design problems, it is the interaction between the two spaces that introduces new problem and solution entities, such as requirements and concept ideas. This so-called co-evolutionary reasoning may arise when an existing problem directly connects to a generated solution, or when a new problem is triggered by a solution [54]. In other words, it can be hypothesised that the emergence of new problem entities during team design activity will most probably follow after exploration of the solution space. An analogous hypothesis can be made for moving from the problem to solution space; that is, the emergence of new solution entities during team design activity will most probably result from problem space exploration. According to [PERSON] et al. [24], the dominant type of co-evolution episodes in the collaborative design are the ones where problem analysis leads to solution attempts rather than the other way around. Hence, the third set of hypotheses can be formulated as follows:  
**Hypothesis 3a (H3a). **_When solving ill-defined design problems, the synthesis of new problem entities is more probable to be a result of solution space exploration._  
**Hypothesis 3b (H3b). **_When solving ill-defined design problems, the synthesis of new solution entities is more probable to be a result of problem space exploration._  
In order to revisit how these particular assumptions about the problem-solution co-evolution work in the context of designing in teams, the formulated hypotheses were tested as part of a protocol analysis study of team conceptual design activity. Protocol analysis, pioneered by [PERSON] and [PERSON] [55], is a frequently employed process-oriented analysis method which utilises observation and recording of subjects' actions to gain an understanding of ways and approaches to designing [56]. The resulting protocols represent designers' step-by-step acts concerning the specific aspect of the investigation and can be used for various quantitative and qualitative analyses of the design process [23; 57]. The establishment of the method has been supported by the ever-increasing capability, efficiency, and affordability of data capturing and analysis tools needed to perform process-oriented studies in design research (audio-video hardware and software) [58]. Protocol analysis was hence selected as the method of choice for capturing the fine-grain problem-solving patterns that would enable testing of the proposed hypotheses. The model and the metrics that were used for capturing and analysing the protocol data represent an extension of the authors' previous work on investigating team conceptual design activity [43].