On Thu, 1 Oct 2015, Travis Scrimshaw wrote:
But in any case, there is no way to run some codes that iterate over
all posets of size n when n is too big. This is because there is no way
to ask UniqueRepresentation to release memory. Or --- will gc.collect()
do this also?
It does release memory when there are no *strong* references back to the
object. A strong reference is would be something like P = Poset({}) or L
= [Poset({})], a top-level variable that points to the object in some
capacity
OK. Still one small question: is there some way to tweak automatic garbage
collection? Like running it if Sage uses more than 4 GB of memory or like?
I have a (non-public) code from Peter Jipsen(*) to compute covering
relations for all lattices of given size up to isomorphism. Let's call it
Lc. I have done basically
def foobar(L): . . . something interesting here . . .
for x in Lc:
L = LatticePoset(x)
if not foobar(L):
print "Counter-example!"
L.show()
break
but this must be modified to
i=0
for x in Lc:
i += 1
if i%100000: gc.collect()
. . .
---
(*) Would be a good addition to SageMath...
--
Jori Mäntysalo
