Tests for fol_fc_ask() (aimacode#543)

Chipe1 · norvig · commit 940f0c98eae0 · 2017-06-09T11:21:48.000-07:00
* Added test for fol_fc_ask()

* Optimization of fol_fc_ask()

* Faster fol_fc_ask()

* Removed subst for rules in KB
diff --git a/logic.py b/logic.py
@@ -914,11 +914,11 @@ def fetch_rules_for_goal(self, goal):
 def fol_fc_ask(KB, alpha):
     """A simple forward-chaining algorithm. [Figure 9.3]"""
     # TODO: Improve efficiency
-    def enum_subst(KB):
-        kb_vars = list({v for clause in KB.clauses for v in variables(clause)})
-        kb_consts = list({c for clause in KB.clauses for c in constant_symbols(clause)})
-        for assignment_list in itertools.product(kb_consts, repeat=len(kb_vars)):
-            theta = {x: y for x, y in zip(kb_vars, assignment_list)}
+    kb_consts = list({c for clause in KB.clauses for c in constant_symbols(clause)})
+    def enum_subst(p):
+        query_vars = list({v for clause in p for v in variables(clause)})
+        for assignment_list in itertools.product(kb_consts, repeat=len(query_vars)):
+            theta = {x: y for x, y in zip(query_vars, assignment_list)}
             yield theta
 
     # check if we can answer without new inferences
@@ -931,16 +931,13 @@ def enum_subst(KB):
         new = []
         for rule in KB.clauses:
             p, q = parse_definite_clause(rule)
-            for theta in enum_subst(KB):
-                if any([set(subst(theta, p)) == set(subst(theta, p_))
-                        for p_ in itertools.combinations(KB.clauses, len(p))]):
+            for theta in enum_subst(p):
+                if set(subst(theta, p)).issubset(set(KB.clauses)):
                     q_ = subst(theta, q)
                     if all([unify(x, q_, {}) is None for x in KB.clauses + new]):
-                        print('Added', q_)
                         new.append(q_)
                         phi = unify(q_, alpha, {})
                         if phi is not None:
-                            print(q_, alpha)
                             yield phi
         if not new:
             break
@@ -1000,6 +997,16 @@ def fol_bc_and(KB, goals, theta):
                'Enemy(Nono, America)'
                ]))
 
+smalltest_kb = FolKB(
+    map(expr, ['Human(Mary)',
+               'Female(x) ==> Likes(x, Chocolate)',
+               'Male(x) ==> Likes(x, IceCream)',
+               'Wife(x, y) & Human(x) ==> Female(x)',
+               'Wife(y, x) & Human(x) ==> Male(x)',
+               'Human(John)',
+               'Wife(Mary, John)'
+               ]))
+
 # ______________________________________________________________________________
 
 # Example application (not in the book).
diff --git a/tests/test_logic.py b/tests/test_logic.py
@@ -261,22 +261,25 @@ def test_ask(query, kb=None):
     assert repr(test_ask('Human(x)')) == '[{x: Mac}, {x: MrsMac}]'
     assert repr(test_ask('Rabbit(x)')) == '[{x: MrsRabbit}, {x: Pete}]'
     assert repr(test_ask('Criminal(x)', crime_kb)) == '[{x: West}]'
+    assert repr(test_ask('Likes(x, Chocolate)', smalltest_kb)) == '[{x: Mary}]'
+    assert repr(test_ask('Likes(x, IceCream)', smalltest_kb)) == '[{x: John}]'
 
 
 def test_fol_fc_ask():
     def test_ask(query, kb=None):
         q = expr(query)
         test_variables = variables(q)
         answers = fol_fc_ask(kb or test_kb, q)
-        print(answers)
         return sorted(
             [dict((x, v) for x, v in list(a.items()) if x in test_variables)
              for a in answers], key=repr)
-    ## Take too long to run
-    #assert repr(test_ask('Farmer(x)')) == '[{x: Mac}]'
-    #assert repr(test_ask('Human(x)')) == '[{x: Mac}, {x: MrsMac}]'
-    #assert repr(test_ask('Rabbit(x)')) == '[{x: MrsRabbit}, {x: Pete}]'
-    #assert repr(test_ask('Criminal(x)', crime_kb)) == '[{x: West}]'
+    assert repr(test_ask('Likes(x, Chocolate)', smalltest_kb)) == '[{x: Mary}]'
+    assert repr(test_ask('Likes(x, IceCream)', smalltest_kb)) == '[{x: John}]'
+    assert repr(test_ask('Criminal(x)', crime_kb)) == '[{x: West}]'
+    assert repr(test_ask('Enemy(x, America)', crime_kb)) == '[{x: Nono}]'
+    assert repr(test_ask('Farmer(x)')) == '[{x: Mac}]'
+    assert repr(test_ask('Human(x)')) == '[{x: Mac}, {x: MrsMac}]'
+    assert repr(test_ask('Rabbit(x)')) == '[{x: MrsRabbit}, {x: Pete}]'
 
 
 def test_d():
