A linear extension of the partial order on $P$ is a total order on the elements of $P$ that is compatible with the partial order.
i1 : P = divisorPoset 12; |
i2 : L = linearExtensions P
o2 = {{1, 2, 3, 6, 4, 12}, {1, 2, 3, 4, 6, 12}, {1, 2, 4, 3, 6, 12}, {1, 3,
------------------------------------------------------------------------
2, 6, 4, 12}, {1, 3, 2, 4, 6, 12}}
o2 : List
|
The flatten of the filtration of $P$ is always a linear extension. This approach is much faster, especially for posets with many linear extensions.
i3 : F = flatten filtration P
o3 = {1, 2, 3, 4, 6, 12}
o3 : List
|
i4 : member(F, L) o4 = true |
The partial order of a chain is the total order of the elements.
i5 : linearExtensions chain 10
o5 = {{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}}
o5 : List
|
This method was ported from John Stembridge's Maple package available at http://www.math.lsa.umich.edu/~jrs/maple.html#posets.
The object linearExtensions is a method function.