We study the law of coexistence of different types of cycles for a
continuous map of the interval. For this we introduce the term of
eccentricity of a pattern and characterize those patterns with a given
eccentricity that are simplest from the point of view of the forcing
relation. We call these patterns X-minimal. We obtain a generalization
of Sharkovski\v\i's Theorem where the notion of period is replaced by
the notion of eccentricity.