i1 : C = chain 7;
i2 : subposet(C, {2,3,5,6}) o2 = Poset{cache => CacheTable{} } GroundSet => {2, 3, 5, 6} RelationMatrix => | 1 1 1 1 | | 0 1 1 1 | | 0 0 1 1 | | 0 0 0 1 | Relations => {{2, 3}, {2, 5}, {2, 6}, {3, 5}, {3, 6}, {5, 6}} o2 : Poset