2 files changed, 14 insertions, 3 deletions
diff --git a/prolog/problems/family_relations/sister_2/common.py b/prolog/problems/family_relations/sister_2/common.py
index 08f44b3..1bc9365 100644
--- a/prolog/problems/family_relations/sister_2/common.py
+++ b/prolog/problems/family_relations/sister_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 = [
@@ -102,10 +103,14 @@ def hint(code, aux_code):
         # as this is after previous hints, by this stage the code probably
         # does return some sensible results already
         # this is an example of using the ordering of hints for easier trigger checks
-        if prolog.engine.ask_one(engine_id,
-            'sister(_, Y), male(Y)') == 'false':
+        if prolog.engine.ask_truth(engine_id, 'sister(_, Y)') and \
+           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'}]
+
         # 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,
diff --git a/prolog/problems/family_relations/sister_2/sl.py b/prolog/problems/family_relations/sister_2/sl.py
index 6c36bce..5fa9d1c 100644
--- a/prolog/problems/family_relations/sister_2/sl.py
+++ b/prolog/problems/family_relations/sister_2/sl.py
@@ -4,7 +4,7 @@ name = 'sister/2'
 slug = 'X je sestra od Y'
 
 description = '''\
-<p><code>sister(?X, ?Y)</code>: <code>X</code> je sestra od <code>Y</code>. Primer:</p>
+<p><code>sister(?X, ?Y)</code>: <code>X</code> je (pol)sestra od <code>Y</code>. Primer:</p>
 <pre>
 ?- sister(vanessa, Y).
   Y = patricia.
@@ -45,6 +45,11 @@ Na primer: <code>X \== Y</code></p>
 <p><code>Y</code> je pravzaprav lahko poljubnega spola.</p>
 ''',
 
+    'nm_instead_of_neq': '''\
+<p>Uporabi raje operator \== namesto operatorja \=. Prvi preveri, da dva objekta nista enaka,
+drugi pa ju poskusi unificirati (narediti enaka).</p>
+''',
+
     'common_parent_needed': '''\
 <p><img src="[%@resource Prolog_sister_05.svg%]" /></p>
 <p>Dobro bi bilo, da imata <code>X</code> in <code>Y</code> vsaj enega skupnega starša.</p>
@@ -56,6 +61,7 @@ Na primer: <code>X \== Y</code></p>
 da spremenljivki, ki ju primerjaš, še nimata določene vrednosti in sta zato različni.
 Prolog ne preverja, če kasneje morda postaneta enaki, ampak samo kakšni sta v trenutku,
 ko naleti na primerjavo.</p>
+<p>Morda pa preprosto preverjaš napačni spremenljivki?</p>
 ''',
 
 }