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

1 files changed, 4 insertions, 4 deletions

diff --git a/prolog/problems/family_relations/grandparent_2/common.py b/prolog/problems/family_relations/grandparent_2/common.py
index 870ceb1..431071e 100644
--- a/prolog/problems/family_relations/grandparent_2/common.py
+++ b/prolog/problems/family_relations/grandparent_2/common.py
@@ -71,6 +71,10 @@ def hint(code, aux_code):
         # TODO: generic hint for:
         # TODO: parent(X, Z1), parent(Z2, Y), Z1 = Z2
 
+        # target predicate seems to always be false
+        if not prolog.engine.ask_truth(engine_id, 'grandparent(_, _)'):
+            return [{'id': 'predicate_always_false'}]
+
         # broken "link" mistake -- no common parent/child Z
         # warning: due to speed considerations this (1024) is knowledge base dependent
         # independent: findall(_, (parent(X, Z1), parent(Z2, Y)), L)
@@ -121,10 +125,6 @@ def hint(code, aux_code):
            prolog.engine.ask_one(engine_id, 'grandparent(_, Y), \+ parent(Y, _)') == 'false':
             return [{'id': 'y_need_not_be_parent'}]
 
-        # target predicate seems to always be false
-        if prolog.engine.ask_one(engine_id, 'grandparent(_, _)') == 'false':
-            return [{'id': 'predicate_always_false'}]
-
     except socket.timeout as ex:
         pass