The "sashimi" model

The sashimi model (so called because it features overlapping phases, like the overlapping fish of Japanese sashimi) was originated by Peter DeGrace. It is sometimes referred to as the "waterfall model with overlapping phases" or "the waterfall model with feedback". Since phases in the sashimi model overlap, information of problem spots can be acted upon during phases of the waterfall model that would typically "precede" others in the pure waterfall model. For example, since the design and implementation phases will overlap in the sashimi model, implementation problems may be discovered during the "design and implementation" phase of the development process.This helps alleviate many of the problems associated with the Big Design Up Front philosophy of the waterfall model.