Added another function maximal_normal_subgroups and did some changes in example

Author: RuchitJagodara

src/sage/groups/perm_gps/permgroup.py

@@ -4108,18 +4108,34 @@ def isomorphism_type_info_simple_group(self):
 
     def minimal_normal_subgroups(self):
         """
-        Return all minimal normal subgroups of the group.
+        Return a list containing all minimal normal subgroups of the group.
 
         EXAMPLES::
 
-            sage: G = SymmetricGroup(4)
-            sage: G.minimal_normal_subgroups()
-            [ Group([ (1,4)(2,3), (1,3)(2,4) ]) ]
+        sage: G = PermutationGroup([(1,2,3),(4,5)])
+        sage: G.minimal_normal_subgroups()
+        [Subgroup generated by [(4,5)] of (Permutation Group with generators [(4,5), (1,2,3)]),
+         Subgroup generated by [(1,2,3)] of (Permutation Group with generators [(4,5), (1,2,3)])]
         """
         gap_subgroups = self.gap().MinimalNormalSubgroups()
         sage_subgroups = [self.subgroup(gap_group=gap_subgroup) for gap_subgroup in gap_subgroups]
         return sage_subgroups
 
+    def maximal_normal_subgroups(self):
+        """
+        Return a list containing those proper normal subgroups of the group G that are maximal among the proper normal subgroups.
+        Gives error if G/G' is infinite, yielding infinitely many maximal normal subgroups.
+
+        EXAMPLES::
+
+            sage: G = SymmetricGroup(4)
+            sage: G.maximal_normal_subgroups()
+            [Subgroup generated by [(2,3,4), (1,2,3)] of (Symmetric group of order 4! as a permutation group)]
+        """
+        gap_subgroups = self.gap().MaximalNormalSubgroups()
+        sage_subgroups = [self.subgroup(gap_group=gap_subgroup) for gap_subgroup in gap_subgroups]
+        return sage_subgroups
+
     ######################  Boolean tests #####################
 
     def is_abelian(self):