sister/2 and brother/2 hints improved.

1 files changed, 7 insertions, 2 deletions

diff --git a/prolog/problems/family_relations/brother_2/common.py b/prolog/problems/family_relations/brother_2/common.py
index c49489e..7f61744 100644
--- a/prolog/problems/family_relations/brother_2/common.py
+++ b/prolog/problems/family_relations/brother_2/common.py
@@ -26,6 +26,7 @@ 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'),
 }
 
 test_cases = [
@@ -73,10 +74,14 @@ def hint(code, aux_code):
             return [{'id': 'common_parent_needed'}]
 
         # Y can be of any gender, incl. female
-        if prolog.engine.ask_one(engine_id,
-            'brother(_, Y), female(Y)') == 'false':
+        if prolog.engine.ask_truth(engine_id, 'brother(_, Y)') and \
+           prolog.engine.ask_one(engine_id, 'brother(_, Y), female(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'}]
+
         # X and Y must be different
         if prolog.util.Token('NEQ', '\==') not in tokens and prolog.engine.ask_truth(engine_id,
             'setof(X, (member(X, [william, alessandro, andrew]), brother(X, X)), L), length(L, 3)'):