  The question of whether significant sub-volumes of a turbulent flow can be
identified by automatic means, independently of a-priori assumptions, is
addressed using the example of two-dimensional decaying turbulence.
Significance is defined as influence on the future evolution of the flow, and
the problem is cast as an unsupervised machine `game' in which the rules are
the Navier--Stokes equations. It is shown that significance is an intermittent
quantity in this particular flow, and that, in accordance with previous
intuition, its most significant features are vortices, while the least
significant ones are dominated by strain. Subject to cost considerations, the
method should be applicable to more general turbulent flows.
