  We present a formal model for studying fashion trends, in terms of three
parameters of fashionable items: (1) their innate utility; (2) individual
boredom associated with repeated usage of an item; and (3) social influences
associated with the preferences from other people. While there are several
works that emphasize the effect of social influence in understanding fashion
trends, in this paper we show how boredom plays a strong role in both
individual and social choices. We show how boredom can be used to explain the
cyclic choices in several scenarios such as an individual who has to pick a
restaurant to visit every day, or a society that has to repeatedly `vote' on a
single fashion style from a collection. We formally show that a society that
votes for a single fashion style can be viewed as a single individual cycling
through different choices.
  In our model, the utility of an item gets discounted by the amount of boredom
that has accumulated over the past; this boredom increases with every use of
the item and decays exponentially when not used. We address the problem of
optimally choosing items for usage, so as to maximize over-all satisfaction,
i.e., composite utility, over a period of time. First we show that the simple
greedy heuristic of always choosing the item with the maximum current composite
utility can be arbitrarily worse than the optimal. Second, we prove that even
with just a single individual, determining the optimal strategy for choosing
items is NP-hard. Third, we show that a simple modification to the greedy
algorithm that simply doubles the boredom of each item is a provably close
approximation to the optimal strategy. Finally, we present an experimental
study over real-world data collected from query logs to compare our algorithms.
