  The Axelrod model is a spatial stochastic model for the dynamics of cultures
which, similarly to the voter model, includes social influence, but differs
from the latter by also accounting for another social factor called homophily,
the tendency to interact more frequently with individuals who are more similar.
Each individual is characterized by its opinions about a finite number of
cultural features, each of which can assume the same finite number of states.
Pairs of adjacent individuals interact at a rate equal to the fraction of
features they have in common, thus modeling homophily, which results in the
interacting pair having one more cultural feature in common, thus modeling
social influence. It has been conjectured based on numerical simulations that
the one-dimensional Axelrod model clusters when the number of features exceeds
the number of states per feature. In this article, we prove this conjecture for
the two-state model with an arbitrary number of features.
