diff --git a/abl/reasoning/base_kb.py b/abl/reasoning/base_kb.py
index 4822e45..848d641 100644
--- a/abl/reasoning/base_kb.py
+++ b/abl/reasoning/base_kb.py
@@ -11,3 +11,11 @@ class BaseKB(ABC):
     def abduce_candidates(self, data_sample: ListData):
         """Placeholder for abduction of the knowledge base."""
         pass
+
+    # TODO: When the output is excessively long, use ellipses as a substitute.
+    def __repr__(self):
+        return (
+            f"<{self.__class__.__name__}(\n"
+            f"    pseudo_label_list: {self.pseudo_label_list!r}\n"
+            f") at {hex(id(self))}>"
+        )
diff --git a/abl/reasoning/ground_kb.py b/abl/reasoning/ground_kb.py
index ed32efd..9f9428d 100644
--- a/abl/reasoning/ground_kb.py
+++ b/abl/reasoning/ground_kb.py
@@ -9,7 +9,7 @@ from .base_kb import BaseKB
 class GroundKB(BaseKB, ABC):
     def __init__(self, pseudo_label_list: List) -> None:
         super().__init__(pseudo_label_list)
-        self.base = self.construct_base()
+        self.GKB = self.construct_base()
 
     @abstractmethod
     def construct_base(self) -> dict:
@@ -20,7 +20,7 @@ class GroundKB(BaseKB, ABC):
         pass
 
     def key2candidates(self, key: Hashable) -> List[List[Any]]:
-        return self.base[key]
+        return self.GKB[key]
 
     def filter_candidates(
         self,
@@ -50,3 +50,12 @@ class GroundKB(BaseKB, ABC):
             require_more_revision=require_more_revision,
             candidates=candidates,
         )
+
+    # TODO: When the output is excessively long, use ellipses as a substitute.
+    def __repr__(self):
+        return (
+            f"<{self.__class__.__name__}(\n"
+            f"    pseudo_label_list: {self.pseudo_label_list!r}\n"
+            f"    GKB: {self.GKB!r}\n"
+            f") at {hex(id(self))}>"
+        )
diff --git a/abl/reasoning/search_based_kb.py b/abl/reasoning/search_based_kb.py
index fb32e7f..e1540fd 100644
--- a/abl/reasoning/search_based_kb.py
+++ b/abl/reasoning/search_based_kb.py
@@ -39,6 +39,7 @@ class SearchBasedKB(BaseKB, ABC):
         super().__init__(pseudo_label_list)
         self.search_strategy = search_strategy
         self.use_cache = use_cache
+        self.cache_root = cache_root
         if self.use_cache:
             if not hasattr(self, "get_key"):
                 raise NotImplementedError("If use_cache is True, get_key should be implemented.")
@@ -100,3 +101,27 @@ class SearchBasedKB(BaseKB, ABC):
                     break
 
         return candidates
+
+    # TODO: When the output is excessively long, use ellipses as a substitute.
+    def __repr__(self):
+        return (
+            f"<{self.__class__.__name__}(\n"
+            f"    pseudo_label_list: {self.pseudo_label_list!r}\n"
+            f"    search_strategy: {self.search_strategy!r}\n"
+            f"    use_cache: {self.use_cache!r}\n"
+            f"    cache_root: {self.cache_root!r}\n"
+            f") at {hex(id(self))}>"
+        )
+
+class Test(SearchBasedKB):
+    def __init__(
+        self,
+        pseudo_label_list: List,
+        search_strategy: Callable[[ListData, int, int], Generator] = incremental_search_strategy,
+        use_cache: bool = True,
+        cache_root: Optional[str] = None,
+    ) -> None:
+        super().__init__(pseudo_label_list, search_strategy, use_cache, cache_root)
+
+    def check_equal(self, data_sample: ListData, y: Any):
+        return data_sample["pred_pseudo_label"][0] == y
diff --git a/examples/hwf/hwf_kb.py b/examples/hwf/hwf_kb.py
index 9f91c8c..15b6312 100644
--- a/examples/hwf/hwf_kb.py
+++ b/examples/hwf/hwf_kb.py
@@ -56,10 +56,10 @@ class HWF_KB(GroundKB):
                 Y.extend(part_Y)
         if Y and isinstance(Y[0], (int, float)):
             X, Y = zip(*sorted(zip(X, Y), key=lambda pair: pair[1]))
-        base = {}
+        GKB = {}
         for x, y in zip(X, Y):
-            base.setdefault(len(x), defaultdict(list))[y].append(x)
-        return base
+            GKB.setdefault(len(x), defaultdict(list))[y].append(x)
+        return GKB
 
     @staticmethod
     def get_key(data_sample: ListData) -> Hashable:
@@ -68,9 +68,9 @@ class HWF_KB(GroundKB):
     def key2candidates(self, key: Hashable) -> List[List[Any]]:
         equation_len, y = key
         if self.max_err == 0:
-            return self.base[equation_len][y]
+            return self.GKB[equation_len][y]
         else:
-            potential_candidates = self.base[equation_len]
+            potential_candidates = self.GKB[equation_len]
             key_list = list(potential_candidates.keys())
             key_idx = bisect.bisect_left(key_list, y)