Added a (wrapper) function to posets.
Added two simple wrapper functions.
Version with both isomorphic_subposets() and isomorphic_subposets_iterator().
Better documentation.
Moved import statement to function; corrections to docs.
This patch adds two quick checks to is_selfdual(). When tested with
all posets of size 7 this runs about 10 times faster. However, this
will slow down worst case, i.e. when poset really is isomorphic to
it's dual.
Slight improvement and '<>' changed to '!='.
Merge branch 't/16909/public/16909' into t/16892/function_to_check_if_a_poset_containt_a_subposet_isomorphic_to_another_poset
Little more optimization; another '<>' to '!='.
Trac #16892: Function to check if a poset containt a subposet isomorphic to another poset

It is, in principle, easy to check if poset A contains a subposet
isomorphic to poset B:

{{{
def has_isomorphic_subposet(A, B):
    for x in Subsets(A.list()):
        if A.subposet(x).is_isomorphic(B):
            return True
    return False
}}}

In reality this is way too slow. Can this be made usefully fast at least
in posets of size 5..10?

URL: http://trac.sagemath.org/16892
Reported by: jmantysalo
Ticket author(s): Jori Mäntysalo
Reviewer(s): Nathann Cohen
Trac #16985: Poset: Faster is_selfdual()

For now at Poset class the code for `is_selfdual()` does just
`is_isomorphic(self.dual())`. It of course works, but is quite slow on
most cases. Before full isomorphic test one can at least check that
number of maximal and minimal elements are same and that sorted lists of
in- and out-degrees are same.

URL: http://trac.sagemath.org/16985
Reported by: jmantysalo
Ticket author(s): Jori Mäntysalo
Reviewer(s): Nathann Cohen