some care for graphs in sage/combinat/posets/mobile.py

Author: dcoudert

src/sage/combinat/posets/lattices.py

@@ -1695,7 +1695,7 @@ def is_cosectionally_complemented(self, certificate=False):
         n = H.order()
         for e in range(n - 2, -1, -1):
             t = 0
-            for uc in H.neighbors_out(e):
+            for uc in H.neighbor_out_iterator(e):
                 t = jn[t, uc]
                 if t == n - 1:
                     break

src/sage/combinat/posets/mobile.py

@@ -112,13 +112,13 @@ def _is_valid_ribbon(self, ribbon):
         num_anchors = 0
 
         for r in ribbon:
-            anchor_neighbors = set(G.neighbors_out(r)).difference(set(R.neighbors_out(r)))
+            anchor_neighbors = set(G.neighbor_out_iterator(r)).difference(set(R.neighbor_out_iterator(r)))
             if len(anchor_neighbors) == 1:
                 num_anchors += 1
             elif len(anchor_neighbors) > 1:
                 return False
 
-            for lc in G.neighbors_in(r):
+            for lc in G.neighbor_in_iterator(r):
                 if lc in ribbon:
                     continue
 
@@ -151,7 +151,7 @@ def _anchor(self):
 
         # Find the anchor vertex, if it exists, and return the edge
         for r in ribbon:
-            anchor_neighbors = set(H.neighbors_out(r)).difference(set(R.neighbors_out(r)))
+            anchor_neighbors = set(H.neighbor_out_iterator(r)).difference(set(R.neighbor_out_iterator(r)))
             if len(anchor_neighbors) == 1:
                 anchor = (r, anchor_neighbors.pop())
                 break