drect maximal elements

src/sage/combinat/independence_posets.py

@@ -220,8 +220,8 @@ def complete_mop(G, S):
     sets = [(S, t)
             for t in Subsets(Set(G).difference(S))
             if not any((i, j) in edges for i in S for j in t)]
-    P = Poset([sets, _inc])
-    return P.maximal_elements()
+    return [u for u in sets
+            if not any(_inc(u, v) for v in sets if v != u)]
 
 
 ##############################################################
@@ -235,17 +235,22 @@ def is_left_modular(L, H=None, verbose=False) -> bool:
 
     ``H`` -- subset of elements; ``H`` is taken as ``L`` if none is given
 
-    ``verbose`` -- indicates whether to give a list of failures; false by default
+    ``verbose`` -- indicates whether to give
+      a list of failures; false by default
 
     OUTPUT:
 
-    if ``verbose == True``, outputs a list of tuples `(y, x, z)` which fail left-modularity.
-    if ``verbose == False``, outputs ``False`` if any one `x \\in H` fails to be left-modular and ``True`` otherwise.
+    if ``verbose == True``, outputs a list of tuples
+    `(y, x, z)` which fail left-modularity.
+    if ``verbose == False``, outputs ``False``
+    if any one `x \\in H` fails to be left-modular and ``True`` otherwise.
 
     ALGORITHM:
 
-    Given a lattice `L` and a subset of elements `H`, an element `x \\in H` is left-modular
-    if for every `y,z \\in L, y \\leq z` the equality `(y \\vee x) \\wedge z = y \\vee (x \\wedge z)`.
+    Given a lattice `L` and a subset of elements `H`,
+    an element `x \\in H` is left-modular
+    if for every `y,z \\in L, y \\leq z`
+    the equality `(y \\vee x) \\wedge z = y \\vee (x \\wedge z)`.
 
     EXAMPLES: