For example, an inexperienced wine drinker will favor the sweetness of Riesling to the density and richness of white Burgundy.

For example, an inexperienced wine drinker will favor the sweetness of Riesling to the density and richness of white Burgundy. However, as the individuals tastes develop he will come to appreciate the layers of buttery and citrus notes of the white Burgundy. This poses a challenge from a modeling perspective. How does the system detect changes in a users behavior? How should the model weight old versus new observations?