Windsurfing aside, many expert windsurfers will ride the same waves as surfers do (wind permitting). At one time referred to as "surfing's ginger haired cousin" by the sport's legendary champion, Robby Naish, windsurfing has long struggled to present a coherent image of the sport to outsiders. As a result of attempts to claim the word "windsurfer" as a trademark, participants have been encouraged to use different names to describe the sport, including "sailboarding" and "boardsailing". The term "windsurfing" has persisted as the accepted name for the sport, and the word "windsurfer" persists for both participants and equipment. Windsurfing is predominately undertaken
Activity recognition accordingly. An example could be the activity of preparing spaghetti, which can be broken down into the subactivities or actions of cutting vegetables, frying the vegetables in a pan and serving it on a plate. Examples of such a hierarchical model are Layered Hidden Markov Models (LHMMs) and the hierarchical hidden Markov model (HHMM), which have been shown to significantly outperform its non-hierarchical counterpart in activity recognition. Different from traditional machine learning approaches, an approach based on data mining has been recently proposed. In the work of Gu et al., the problem of activity recognition is formulated as a pattern-based