  In this paper we introduce a method for determining local interaction rules
in animal swarms. The method is based on the assumption that the behavior of
individuals in a swarm can be treated as a set of mechanistic rules.
  The principal idea behind the technique is to vary parameters that define a
set of hypothetical interactions to minimize the deviation between the forces
estimated from observed animal trajectories and the forces resulting from the
assumed rule set. We demonstrate the method by reconstructing the interaction
rules from the trajectories produced by a computer simulation.
