Improved hints for ancestor/2 and descendant/2.

1 files changed, 13 insertions, 3 deletions

diff --git a/prolog/problems/family_relations/ancestor_2/common.py b/prolog/problems/family_relations/ancestor_2/common.py
index 6690e00..9346e5f 100644
--- a/prolog/problems/family_relations/ancestor_2/common.py
+++ b/prolog/problems/family_relations/ancestor_2/common.py
@@ -27,8 +27,10 @@ hint_type = {
     'grandparent_used_markup': HintPopup('grandparent_used_markup'),
     'base_case': Hint('base_case'),
     'ancestor_to_oneself': Hint('ancestor_to_oneself'),
+    'ancestor_to_oneself_with_or': Hint('ancestor_to_oneself_with_or'),
     'descendant_need_not_be_parent': Hint('descendant_need_not_be_parent'),
     'wrong_direction': Hint('wrong_direction'),
+    'only_two_levels_deep': Hint('only_two_levels_deep'),
     'timeout': Hint('timeout'),
 }
 
@@ -83,15 +85,23 @@ def hint(code, aux_code):
                    [{'id': 'grandparent_used'}]
 
         # missing/failed base case
-        # TODO: how will ask_truth handle/return timeouts...
-        # TODO: timeout is the same as fail in this particular case
         if prolog.engine.ask_truthTO(engine_id,
             'findall(X/Y, parent(X, Y), L), member(X/Y, L), \+ ancestor(X, Y)'):
             return [{'id': 'base_case'}]
 
+        # two levels deep relation (up to grandparent) only
+        # warning: knowledge base dependent
+        if prolog.engine.ask_truthTO(engine_id,
+            'findall(_, ancestor(X, Y), L1), length(L1, 23) ; \
+             findall(_, ancestor(X, Y), L2), length(L2, 55)'):
+            return [{'id': 'only_two_levels_deep'}]
+
         # ancestor to oneself
         if prolog.engine.ask_truthTO(engine_id, 'ancestor(X, X)'):
-            return [{'id': 'ancestor_to_oneself'}]
+            if prolog.util.Token('SEMI', ';') in tokens:
+                return [{'id': 'ancestor_to_oneself_with_or'}]
+            else:
+                return [{'id': 'ancestor_to_oneself'}]
 
         # descendant instead of ancestor (wrong direction)
         # warning: knowledge base dependent