diff --git a/abducer/kb.py b/abducer/kb.py
index 032731c..0ba1479 100644
--- a/abducer/kb.py
+++ b/abducer/kb.py
@@ -115,7 +115,80 @@ class add_KB(KBBase):
     def __len__(self):
         return sum(self._dict_len(v) for v in self.base.values())
 
+class ClsKB(KBBase):
+    def __init__(self, X, Y = None):
+        super().__init__()
+        self.base = {}
+        
+        if X is None:
+            return
 
+        if Y is None:
+            Y = [None] * len(X)
+
+        for x, y in zip(X, Y):
+            self.base.setdefault(len(x), defaultdict(list))[y].append(np.array(x))
+
+    def get_candidates(self, key, length = None):
+        if key is None:
+            return self.get_all_candidates()
+
+        length = self._length(length)
+
+        return sum([self.base[l][key] for l in length], [])
+    
+    def get_all_candidates(self):
+        return sum([sum(v.values(), []) for v in self.base.values()], [])
+
+    def _dict_len(self, dic):
+        return sum(len(c) for c in dic.values())
+
+    def __len__(self):
+        return sum(self._dict_len(v) for v in self.base.values())
+
+class RegKB(KBBase):
+    def __init__(self, X, Y = None):
+        super().__init__()
+        tmp_dict = {}
+        for x, y in zip(X, Y):
+            tmp_dict.setdefault(len(x), defaultdict(list))[y].append(np.array(x))
+
+        self.base = {}
+        for l in tmp_dict.keys():
+            data = sorted(list(zip(tmp_dict[l].keys(), tmp_dict[l].values())))
+            X = [x for y, x in data]
+            Y = [y for y, x in data]
+            self.base[l] = (X, Y)
+               
+    def get_candidates(self, key, length = None):
+        if key is None:
+            return self.get_all_candidates()
+
+        length = self._length(length)
+
+        min_err = 999999
+        candidates = []
+        for l in length:
+            X, Y = self.base[l]
+
+            idx = bisect.bisect_left(Y, key)
+            begin = max(0, idx - 1)
+            end = min(idx + 2, len(X))
+
+            for idx in range(begin, end):
+                err = abs(Y[idx] - key)
+                if abs(err - min_err) < 1e-9:
+                    candidates.extend(X[idx])
+                elif err < min_err:
+                    candidates = copy.deepcopy(X[idx])
+                    min_err = err
+        return candidates
+
+    def get_all_candidates(self):
+        return sum([sum(D[0], []) for D in self.base.values()], [])
+
+    def __len__(self):
+        return sum([sum(len(x) for x in D[0]) for D in self.base.values()])
 
 if __name__ == "__main__":
     pseudo_label_list = list(range(10))
@@ -130,4 +203,28 @@ if __name__ == "__main__":
     print()
     res = kb.get_candidates(7, length = 3)
     print(res)
+    print()
+    
+    X = ["1+1", "0+1", "1+0", "2+0", "1+0+1"]
+    Y = [2, 1, 1, 2, 2]
+    kb = ClsKB(X, Y)
+    print(len(kb))
+    res = kb.get_candidates(2, 5)
+    print(res)
+    res = kb.get_candidates(2, 3)
+    print(res)
+    res = kb.get_candidates(None)
+    print(res)
+    print()
+    
+    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 = RegKB(X, Y)
+    print(len(kb))
+    res = kb.get_candidates(1.6)
+    print(res)
+    res = kb.get_candidates(1.6, length = 9)
+    print(res)
+    res = kb.get_candidates(None)
+    print(res)