Ordering conditions
===================

Since the efficiency of the matcher (a Rete network) [Forg81] depends heavily
upon the order of a production's conditions, the chunking mechanism attempts
to write the chunk's conditions in the most favorable order.  At each stage,
the condition-ordering algorithm tries to determine which eligible condition,
if placed next, will lead to the fewest number of partial instantiations when
the chunk is matched. A condition that matches an object with a multi-valued
attribute will lead to multiple partial instantiations, so it is generally
more efficient to place these conditions later in the ordering.