  A few years ago we identified a recursion that works directly with the gaps
among the generators in each stage of Eratosthenes sieve. This recursion
provides explicit enumerations of sequences of gaps among the generators, which
are known as constellations.
  As the recursion proceeds, adjacent gaps within longer constellations are
added together to produce shorter constellations of the same sum. These
additions or closures correspond to removing composite numbers that are
divisible by the prime for that stage of Eratosthenes sieve. Although we don't
know where in the cycle of gaps a closure will occur, we can enumerate exactly
how many copies of various constellations will survive each stage.
  In this paper, we study these systems of constellations of a fixed sum.
Viewing them as discrete dynamic systems, we are able to characterize the
populations of constellations for sums including the first few primorial
numbers: 2, 6, 30.
  Since the eigenvectors of the discrete dynamic system are independent of the
prime -- that is, independent of the stage of the sieve -- we can characterize
the asymptotic behavior exactly. In this way we can give exact ratios of the
occurrences of the gap 2 to the occurrences of other small gaps for all stages
of Eratosthenes sieve.
