diff --git a/abducer/kb.py b/abducer/kb.py
index c3ddff0..9c09765 100644
--- a/abducer/kb.py
+++ b/abducer/kb.py
@@ -99,10 +99,11 @@ class add_KB(KBBase):
                 address_idx_list = list(combinations(list(range(len(pred_res))), address_num))
                 for address_idx in address_idx_list:
                     for c in all_address_candidate:
-                        pred_res_array = np.array(pred_res)
-                        pred_res_array[np.array(address_idx)] = c
-                        if(np.count_nonzero(np.array(c) != np.array(pred_res)[np.array(address_idx)]) == address_num and self.logic_forward(pred_res_array) == key):
-                            candidates.append(pred_res_array)
+                        if(np.count_nonzero(np.array(c) != np.array(pred_res)[np.array(address_idx)]) == address_num):
+                            pred_res_array = np.array(pred_res)
+                            pred_res_array[np.array(address_idx)] = c
+                            if(self.logic_forward(pred_res_array) == key):
+                                candidates.append(pred_res_array)
             
             if(len(candidates) > 0):
                 min_address_num = address_num
@@ -115,10 +116,11 @@ class add_KB(KBBase):
             address_idx_list = list(combinations(list(range(len(pred_res))), address_num))
             for address_idx in address_idx_list:
                 for c in all_candidate:
-                    pred_res_array = np.array(pred_res)
-                    pred_res_array[np.array(address_idx)] = c
-                    if(np.count_nonzero(np.array(c) != pred_res_array[np.array(address_idx)]) == address_num and self.logic_forward(pred_res_array) == key):
-                        candidates.append(pred_res_array)
+                    if(np.count_nonzero(np.array(c) != np.array(pred_res)[np.array(address_idx)]) == address_num):
+                        pred_res_array = np.array(pred_res)
+                        pred_res_array[np.array(address_idx)] = c
+                        if(self.logic_forward(pred_res_array) == key):
+                            candidates.append(pred_res_array)
 
         return candidates, min_address_num, address_num
         
@@ -310,10 +312,16 @@ if __name__ == "__main__":
     print(res)
     print()
     
+    pseudo_label_list = list(range(10)) + ['+', '-', '*', '/']
+    kb = hwf_KB(pseudo_label_list, max_len = 5)
+    print('len(kb):', len(kb))
+    print()
+    
+    
     X = ["1+1", "0+1", "1+0", "2+0", "1+0+1"]
     Y = [2, 1, 1, 2, 2]
     kb = cls_KB(X, Y)
-    print(len(kb))
+    print('len(kb):', len(kb))
     res = kb.get_candidates(2, 5)
     print(res)
     res = kb.get_candidates(2, 3)
@@ -325,7 +333,7 @@ if __name__ == "__main__":
     X = ["1+1", "0+1", "1+0", "2+0", "1+0.5", "0.75+0.75"]
     Y = [2, 1, 1, 2, 1.5, 1.5]
     kb = reg_KB(X, Y)
-    print(len(kb))
+    print('len(kb):', len(kb))
     res = kb.get_candidates(1.6)
     print(res)
     res = kb.get_candidates(1.6, length = 9)