diff --git a/abl/reasoning/kb.py b/abl/reasoning/kb.py
index f5164d2..be41aa2 100644
--- a/abl/reasoning/kb.py
+++ b/abl/reasoning/kb.py
@@ -118,7 +118,9 @@ class KBBase(ABC):
         y : Any
             Ground truth of the reasoning result for the example.
         x : List[Any]
-            The corresponding input example.
+            The corresponding input example. If the information from the input 
+            is not required in the reasoning process, then this parameter will not have 
+            any effect.
         max_revision_num : int
             The upper limit on the number of revised labels for each example.
         require_more_revision : int
@@ -169,7 +171,9 @@ class KBBase(ABC):
         y : Any
             Ground truth of the reasoning result for the example.
         x : List[Any]
-            The corresponding input example.
+            The corresponding input example. If the information from the input 
+            is not required in the reasoning process, then this parameter will not have 
+            any effect.
         revision_idx : List[int]
             A list specifying indices of where revisions should be made to the pseudo-label example.
 
@@ -231,7 +235,9 @@ class KBBase(ABC):
         y : Any
             Ground truth of the reasoning result for the example.
         x : List[Any]
-            The corresponding input example.
+            The corresponding input example. If the information from the input 
+            is not required in the reasoning process, then this parameter will not have 
+            any effect.
         max_revision_num : int
             The upper limit on the number of revisions.
         require_more_revision : int
@@ -523,7 +529,9 @@ class PrologKB(KBBase):
         y : Any
             Ground truth of the reasoning result for the example.
         x : List[Any]
-            The corresponding input example.
+            The corresponding input example. If the information from the input 
+            is not required in the reasoning process, then this parameter will not have 
+            any effect.
         revision_idx : List[int]
             A list specifying indices of where revisions should be made to the pseudo-label example.
 
@@ -555,7 +563,9 @@ class PrologKB(KBBase):
         y : Any
             Ground truth of the reasoning result for the example.
         x : List[Any]
-            The corresponding input example.
+            The corresponding input example. If the information from the input 
+            is not required in the reasoning process, then this parameter will not have 
+            any effect.
         revision_idx : List[int]
             A list specifying indices of where revisions should be made to the pseudo-label example.
 
diff --git a/docs/Intro/Reasoning.rst b/docs/Intro/Reasoning.rst
index 3c1836d..2af667f 100644
--- a/docs/Intro/Reasoning.rst
+++ b/docs/Intro/Reasoning.rst
@@ -33,8 +33,8 @@ knowledge base. In addition, ABL-Package also offers several predefined
 subclasses of ``KBBase`` (e.g., ``PrologKB`` and ``GroundKB``), 
 which we can utilize to build our knowledge base more conveniently.
 
-Building a knowledge base from `KBBase`
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Building a knowledge base from ``KBBase``
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 For the user-built KB from ``KBBase`` (a derived subclass), it's only
 required to pass the ``pseudo_label_list`` parameter in the ``__init__`` function
@@ -43,8 +43,15 @@ and override the ``logic_forward`` function:
 -  ``pseudo_label_list`` is the list of possible pseudo-labels (also,
    the output of the machine learning model).
 -  ``logic_forward`` defines how to perform (deductive) reasoning,
-   i.e. matching each pseudo-label example (often consisting of multiple 
-   pseudo-labels) to its reasoning result.
+   i.e. matching each pseudo-label example to its reasoning result. 
+
+.. warnings::
+
+   Generally, the overridden function ``logic_forward`` provided by the user accepts 
+   only one parameter, ``pseudo_label`` (a pseudo-label example), However, for certain 
+   scenarios, deductive reasoning in the knowledge base may necessitate information 
+   from the input. When this happens, ``logic_forward`` can also accept two parameters: 
+   ``pseudo_label`` and ``x``.
 
 After that, other operations, including how to perform abductive
 reasoning, will be **automatically** set up.
@@ -213,13 +220,16 @@ available, we aim to let the candidate do not largely revise the
 previously identified pseudo-label example.
 
 ``KBBase`` (also, ``GroundKB`` and ``PrologKB``) implement the method
-``abduce_candidates(pseudo_label, y, max_revision_num, require_more_revision)``
+``abduce_candidates(pseudo_label, y, x, max_revision_num, require_more_revision)``
 for performing abductive reasoning, where the parameters are:
 
 -  ``pseudo_label``, the pseudo-label example to be revised by abductive
    reasoning, usually generated by the learning part.
 -  ``y``, the ground truth of the reasoning result for the example. The
    returned candidates should be compatible with it.
+- ``x``, the corresponding input example. If the information from the input 
+   is not required in the reasoning process, then this parameter will not have 
+   any effect.
 -  ``max_revision_num``, an int value specifying the upper limit on the
    number of revised labels for each example.
 -  ``require_more_revision``, an int value specifying additional number