Added implementation of Three Block Tower and Cake Problem in Planning module

Author: rahulptel

planning.py

@@ -175,3 +175,65 @@ def goal_test(kb):
     leave_overnight = Action(expr("LeaveOvernight"), [precond_pos, precond_neg], [effect_add, effect_rem])
 
     return PDLL(init, [remove, put_on, leave_overnight], goal_test)
+
+def three_block_tower():
+    init = [expr('On(A, Table)'),
+            expr('On(B, Table)'),
+            expr('On(C, A)'),
+            expr('Block(A)'),
+            expr('Block(B)'),
+            expr('Block(C)'),
+            expr('Clear(B)'),
+            expr('Clear(C)')]
+
+    def goal_test(kb):
+        required = [expr('On(A, B)'), expr('On(B, C)')]
+        for q in required:
+            if kb.ask(q) is False:
+                return False
+        return True
+
+    ## Actions
+    #  Move
+    precond_pos = [expr('On(b, x)'), expr('Clear(b)'), expr('Clear(y)'), expr('Block(b)'),
+                   expr('Block(y)'), expr('b != x'), expr('b != y'), expr('x != y')]
+    precond_neg = []
+    effect_add = [expr('On(b, y)'), expr('Clear(x)')]
+    effect_rem = [expr('On(b, x)'), expr('Clear(y)')]
+    move = Action(expr('Move(b, x, y)'), [precond_pos, precond_neg], [effect_add, effect_rem])
+    
+    #  MoveToTable
+    precond_pos = [expr('On(b, x)'), expr('Clear(b)'), expr('Block(b)'), expr('b != x')]
+    precond_neg = []
+    effect_add = [expr('On(b, Table)'), expr('Clear(x)')]
+    effect_rem = [expr('On(b, x)')]
+    moveToTable = Action(expr('MoveToTable(b, x)'), [precond_pos, precond_neg], [effect_add, effect_rem])
+
+    return PDLL(init, [move, moveToTable], goal_test)
+
+def cake():
+    init = [expr('Have(Cake)')]
+
+    def goal_test(kb):
+        required = [expr('Have(Cake)'), expr('Eaten(Cake)')]
+        for q in required:
+            if kb.ask(q) is False:
+                return False
+        return True
+
+    ## Actions
+    #  Eat
+    precond_pos = [expr('Have(Cake)')]
+    precond_neg = []
+    effect_add = [expr('Eaten(Cake)')]
+    effect_rem = [expr('Have(Cake)')]
+    eat = Action(expr('Eat(Cake)'), [precond_pos, precond_neg], [effect_add, effect_rem])
+    
+    #  Bake
+    precond_pos = []
+    precond_neg = [expr('Have(Cake)')]
+    effect_add = [expr('Have(Cake)')]
+    effect_rem = []
+    bake = Action(expr('Bake(Cake)'), [precond_pos, precond_neg], [effect_add, effect_rem])
+
+    return PDLL(init, [eat, bake], goal_test)

tests/test_planning.py

@@ -34,3 +34,25 @@ def test_air_cargo():
         p.act(action)
 
     assert p.goal_test()
+
+def test_spare_tire():
+    p = spare_tire()
+    assert p.goal_test() is False
+    solution = [expr("Remove(Flat, Axle)"),
+                expr("Remove(Spare, Trunk)"),
+                expr("PutOn(Spare, Axle)")]
+
+    for action in solution:
+        p.act(action)
+
+def test_three_block_tower():
+    p = three_block_tower()
+    assert p.goal_test() is False
+    solution = [expr("MoveToTable(C, A)"),
+                expr("Move(B, Table, C)"),
+                expr("Move(A, Table, B)")]
+
+    for action in solution:
+        p.act(action)
+
+