From 90dbc3fa624d62e093bea7b90a72a28ad216f7bd Mon Sep 17 00:00:00 2001
From: Aleksander Sadikov <aleksander.sadikov@fri.uni-lj.si>
Date: Mon, 29 Feb 2016 00:27:21 +0100
Subject: Additional improvements to hints for mother, father, grandparent,
 sister, and brother problems.

---
 prolog/problems/family_relations/brother_2/common.py | 8 ++++----
 prolog/problems/family_relations/father_2/common.py  | 8 ++++----
 prolog/problems/family_relations/mother_2/common.py  | 8 ++++----
 prolog/problems/family_relations/sister_2/common.py  | 8 ++++----
 4 files changed, 16 insertions(+), 16 deletions(-)

(limited to 'prolog/problems/family_relations')

diff --git a/prolog/problems/family_relations/brother_2/common.py b/prolog/problems/family_relations/brother_2/common.py
index 0ad74c3..87f27a3 100644
--- a/prolog/problems/family_relations/brother_2/common.py
+++ b/prolog/problems/family_relations/brother_2/common.py
@@ -65,6 +65,10 @@ def hint(code, aux_code):
     try:
         engine_id, output = prolog.engine.create(code=code+aux_code, timeout=1.0)
 
+        # target predicate seems to always be false
+        if not prolog.engine.ask_truth(engine_id, 'brother(_, _)'):
+            return [{'id': 'predicate_always_false'}]
+
         # X must be male
         if prolog.engine.ask_truth(engine_id, 'female(X), brother(X, _)'):
             return [{'id': 'x_must_be_male'}]
@@ -83,10 +87,6 @@ def hint(code, aux_code):
         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, 'brother(_, _)') == 'false':
-            return [{'id': 'predicate_always_false'}]
-
         # 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)'):
diff --git a/prolog/problems/family_relations/father_2/common.py b/prolog/problems/family_relations/father_2/common.py
index 11f0742..31109c9 100644
--- a/prolog/problems/family_relations/father_2/common.py
+++ b/prolog/problems/family_relations/father_2/common.py
@@ -67,6 +67,10 @@ def hint(code, aux_code):
     try:
         engine_id, output = prolog.engine.create(code=code+aux_code, timeout=1.0)
 
+        # target predicate seems to always be false
+        if not prolog.engine.ask_truth(engine_id, 'father(_, _)'):
+            return [{'id': 'predicate_always_false'}]
+
         # OR (;) instead of AND (,)
         # this hint has to be before the next two
         # as otherwise those two would always override it
@@ -102,10 +106,6 @@ def hint(code, aux_code):
            prolog.engine.ask_one(engine_id, 'father(_, 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, 'father(_, _)') == 'false':
-            return [{'id': 'predicate_always_false'}]
-
     except socket.timeout as ex:
         pass
 
diff --git a/prolog/problems/family_relations/mother_2/common.py b/prolog/problems/family_relations/mother_2/common.py
index 1bb7a4b..a7da458 100644
--- a/prolog/problems/family_relations/mother_2/common.py
+++ b/prolog/problems/family_relations/mother_2/common.py
@@ -68,6 +68,10 @@ def hint(code, aux_code):
     try:
         engine_id, output = prolog.engine.create(code=code+aux_code, timeout=1.0)
 
+        # target predicate seems to always be false
+        if not prolog.engine.ask_truth(engine_id, 'mother(_, _)'):
+            return [{'id': 'predicate_always_false'}]
+
         # OR (;) instead of AND (,)
         # this hint has to be before the next two
         # as otherwise those two would always override it
@@ -103,10 +107,6 @@ def hint(code, aux_code):
            prolog.engine.ask_one(engine_id, 'mother(_, 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, 'mother(_, _)') == 'false':
-            return [{'id': 'predicate_always_false'}]
-
     except socket.timeout as ex:
         pass
 
diff --git a/prolog/problems/family_relations/sister_2/common.py b/prolog/problems/family_relations/sister_2/common.py
index 1234985..2be3ab3 100644
--- a/prolog/problems/family_relations/sister_2/common.py
+++ b/prolog/problems/family_relations/sister_2/common.py
@@ -91,6 +91,10 @@ def hint(code, aux_code):
     try:
         engine_id, output = prolog.engine.create(code=code+aux_code, timeout=1.0)
 
+        # target predicate seems to always be false
+        if not prolog.engine.ask_truth(engine_id, 'sister(_, _)'):
+            return [{'id': 'predicate_always_false'}]
+
         # X must be female
         if prolog.engine.ask_truth(engine_id, 'male(X), sister(X, _)'):
             return [{'id': 'x_must_be_female'}]
@@ -112,10 +116,6 @@ def hint(code, aux_code):
         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)
         if prolog.util.Token('NEQ', '\==') not in tokens and prolog.engine.ask_truth(engine_id,
-- 
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