Additional improvements to hints for mother, father, grandparent, sister, and brother problems.

1 files changed, 9 insertions, 4 deletions

diff --git a/prolog/problems/family_relations/sister_2/common.py b/prolog/problems/family_relations/sister_2/common.py
index 1bc9365..1234985 100644
--- a/prolog/problems/family_relations/sister_2/common.py
+++ b/prolog/problems/family_relations/sister_2/common.py
@@ -26,7 +26,8 @@ hint_type = {
     'y_can_be_of_any_gender': Hint('y_can_be_of_any_gender'),
     'x_y_must_be_different': Hint('x_y_must_be_different'),
     'neq_used_too_early': Hint('neq_used_too_early'),
-    'nm_instead_of_neq': Hint('nm_instead_of_neq'),
+    'neq+_instead_of_neq': Hint('neq+_instead_of_neq'),
+    'predicate_always_false': Hint('predicate_always_false'),
 }
 
 test_cases = [
@@ -107,9 +108,13 @@ def hint(code, aux_code):
            prolog.engine.ask_one(engine_id, 'sister(_, Y), male(Y)') == 'false':
             return [{'id': 'y_can_be_of_any_gender'}]
 
-        # use of \= instead of \==
-        if prolog.util.Token('NEQ', '\=') in tokens:
-            return [{'id': 'nm_instead_of_neq'}]
+        # use of \= or =\= instead of \==
+        if prolog.util.Token('NEQU', '\=') in tokens or prolog.util.Token('NEQA', '=\=') in tokens:
+            return [{'id': 'neq+_instead_of_neq'}]
+
+        # target predicate seems to always be false
+        if prolog.engine.ask_one(engine_id, 'sister(_, _)') == 'false':
+            return [{'id': 'predicate_always_false'}]
 
         # X and Y must be different
         # this is the last code-specific hint (when everything else doesn't trigger anymore)