What
is the chemical freeze-out temperature in heavy ion collisions? Are
light
and strange flavors chemically equilibrated at freeze-out? What is
the magnitude of re-interaction between hadron formation and thermal
freeze-out? What ensemble is most physically appropriate for a statistical
description of strangeness production?
We will show how models where answers to these questions differ give
a different dependance of fluctuations on yields, and argue that each
of these questions, at present controversial, can be experimentally
investigated through quantitatively studying both yields and fluctuations
of light and strange particles.
We will describe some difficoulties inherent in quantitative study
of fluctuations, and give preliminary model-data comparisons.