calcyman wrote:It's also a quantitative issue rather than a qualitative one: every oscillator/spaceship has some RAM threshold beyond which HashLife will memoize every sufficiently small tile that the simulation can 'run away' exponentially quickly. I think I've managed to do this with the Caterpillar using several gigabytes of RAM.
Yup, bounding box and population both turn out to be very nearly irrelevant in most cases. The number of distinct hashtiles does go up as the bounding box increases, but usually in a very large pattern there's enough repetition that the increase is closer to logarithmic than linear.
A pattern that's a factor of 100 bigger might need only slightly more memory to run -- or sometimes slightly less, or occasionally a lot less. The big deciding factor is the period, as gmc_nxtman mentioned -- with weird super extra bonus points if the period and spaceship step size both happen to be an exact power of two.
It's fairly easy now to build an oblique Geminoid or Orthogonoid that will use the 2^N trick to run as quickly in Golly as the waterbear does -- once Golly has seen all the hashtiles once. The simulation will crawl along for one cycle (for the Orthogonoid) or the first several cycles (for the oblique Geminoid) and then accelerate radically -- kind of like those standard space-movie shots of the Enterprise or the Millennium Falcon going into hyperdrive.