In her book, [[Torres - Continuous Discovery Habits|Continuous Discovery Habits]], [[Teresa Torres]] writes about some of [[Nigel Cross]]'s findings when comparing expert designers with novice designers across multiple disciplines: > … the best designers evolve the problem space and the solution space together. As they explore potential solutions, they learn more about the problem, and, as they learn more about the problem, new solutions become possible. These two activities are intrinsically intertwined. The problem space and the solution space evolve together. This challenges the tidiness of the [[Double-diamond model]], which outlines the problem space and solution space as happening linearly.