Currently Posets.PentagonPoset().is_antichain_of_poset([2,3,'junk'])
returns False and Posets.PentagonPoset().is_antichain_of_poset(['junk',2,3])raises an error. At https://trac.sagemath.org/ticket/19078 I and Travis have different opinion about which one is the right answer. So please give your opinion.
* * *I think we all agree that this should be consistent, and something like is_induced_subposet() should also behave in the same way.
-- Jori Mäntysalo
