On Thu, 28 Aug 2014, Nathann Cohen wrote:
Yes, you do need this induced=True otherwise the chain contains all
other (smaller) posets :-P
But
def has_isomorphic_subposet(A, B):
for x in Subsets(A.list(), k=B.cardinality()):
if A.subposet(x).is_isomorphic(B):
return True
return False
def has_isomorphic_subposet2(A, B):
if A.hasse_diagram().subgraph_search(B.hasse_diagram(),induced=True) is
None:
return False
return True
Diamond=Poset( ([1,2,3,4], [[1,2],[1,3],[2,4],[3,4]]) )
N5=Poset( ([1,2,3,4,5], [[1,2],[1,3],[3,4],[2,5],[4,5]]) )
print has_isomorphic_subposet(N5, Diamond)
print has_isomorphic_subposet2(N5, Diamond)
outputs
True
False
And it should be much faster than the listing from your trac ticket
(which you can close if your problem is solved, or recycle into a
ticket to implement the feature)
If there is an easy solution for this, I can make a function to finite
posets class. Hence I'm not going to close ticket yet.
--
Jori Mäntysalo
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