Merge branch 'forward_chaining_implementation' of https://github.com/KarimAly12/Python into forward_chaining_implementation

Author: KarimAly12

inference_engine_algorithms/forward_chaining.py

@@ -1,26 +1,27 @@
-'''
+"""
 The forward-chaining algorithm PL-FC-ENTAILS? (KB, q) determines if a single proposition
 symbol q—the query—is entailed by a knowledge base of definite clauses. It begins from
-known facts (positive literals) in the knowledge base. 
+known facts (positive literals) in the knowledge base.
 known facts (positive literals) in the knowledge base.
 
 Reference: https://dl.ebooksworld.ir/books/Artificial.Intelligence.A.Modern.Approach.4th.Edition.Peter.Norvig.%20Stuart.Russell.Pearson.9780134610993.EBooksWorld.ir.pdf
 
-'''
+"""
 
 import re
 
+
 def find_symbols_in_kb(knowledge_base: list[str]) -> dict:
-    '''
+    """
     Find all unique symbols in the Knowledge_base.
     :param knowledge_base: a list of string of definite clauses
     :returns: a dictionary with symbols as the keys their values are False
-    '''
+    """
 
     inferred = {}
 
     for i in range(len(knowledge_base)):
-        symbols = re.findall(r'[a-zA-Z]', knowledge_base[i])
+        symbols = re.findall(r"[a-zA-Z]", knowledge_base[i])
         for symbol in symbols:
             if symbol not in inferred:
                 inferred[symbol] = False
@@ -30,30 +31,29 @@ def find_symbols_in_kb(knowledge_base: list[str]) -> dict:
 
 def number_of_symbols_in_premise(knowledge_base: list[str]) -> dict:
 
-    '''
+    """
     Count the number of prposiotion symbols in each premise of KB clause.
     :param knowledge_base: a list of string of definite clauses
     :returns: a dict with keys as the premise and value is count of symbols in premise
-    '''
+    """
 
     count = {}
     for clause in knowledge_base:
-        if(len(clause) != 1):
+        if len(clause) != 1:
             index = clause.find("=>")
             premise = clause[:index]
-            letters = ''.join(e for e in premise if e.isalpha())
+            letters = "".join(e for e in premise if e.isalpha())
             count[premise] = len(letters)
 
     return count
 
 
 def get_known_facts(knowledge_base: list[str]) -> list[str]:
-    '''
-    Get the known facts in KB.
+    """
+    Get the known facts in KB
     :param knowledge_base: a list of string of definite clauses
     :returns: list of facts
-
-    '''
+    """
 
     facts = []
     for clause in knowledge_base:
@@ -63,10 +63,8 @@ def get_known_facts(knowledge_base: list[str]) -> list[str]:
     return facts
 
 
-
-
-def forward_chaining(knowledge_base: list[str], query:str) -> bool:
-    ''' Forward chaining on Knowledge Base(KB) of definite clauses.
+def forward_chaining(knowledge_base: list[str], query: str) -> bool:
+    """Forward chaining on Knowledge Base(KB) of definite clauses
     :param knowledge_base: a list of string of definite clauses
     :param query: a single proposition symbol 
     :returns: If the query entailed by the KB or not?
@@ -79,15 +77,16 @@ def forward_chaining(knowledge_base: list[str], query:str) -> bool:
     >>> forward_chaining(input_kb, "C")
     False
 
-    '''
+    """
 
     count = number_of_symbols_in_premise(knowledge_base)
     inferred = find_symbols_in_kb(knowledge_base)
     queue = get_known_facts(knowledge_base)
 
-    while(len(queue) > 0):
+    while len(queue) > 0:
         p = queue.pop()
-        if p == query: return True
+        if p == query:
+            return True
         if not inferred[p]:
             inferred[p] = True
             for clause in knowledge_base:
@@ -101,38 +100,25 @@ def forward_chaining(knowledge_base: list[str], query:str) -> bool:
     return False
 
 
+KB = ["P => Q", "L & M => P", "B&L=> M", "A&P=>L", "A&B=>L", "A", "B"]
 
-
-KB = [
-        "P => Q",
-        "L & M => P",
-        "B&L=> M",
-        "A&P=>L", 
-        "A&B=>L", 
-        "A",
-        "B" ]
-
-'''
+"""
 1)- KB must be written in horn form.
 2)- It must be written as an implcaion whose
-its premise(head) must be conjunction of positive literals and its conclusion(body).
-3)- Contains facts about the world as single proposition symbol.
-'''
+its premise(head) must be conjunction of positive literals and its conclusion(body)
+3)- It must contains facts about the world  written as a single proposition symbol
+"""
 QUERY = "Q"
 
-'''
-Query is a signe proposition symbol that you check if it is entailed by the KB.
+"""
+Query is a signe proposition symbol that you check if it is entailed by the KB
 
-'''
+"""
 
 if __name__ == "__main__":
-
-    
-
     import doctest
 
     doctest.testmod(verbose=True)
-   
 
     result = forward_chaining(KB, QUERY)
-    print(result)
+    print(result)