def from_str(cls, clause_str):
"""
Creates a Horn clause from a Horn clause string.
:param clause_str:
:return: HornClause
"""
if clause_str[-1] != '.' or clause_str.find(';') != -1:
raise ValueError('Invalid clause.')
if clause_str.find('%') != -1:
return None
clause_str = clause_str.replace('?-', ':-')
conclusion_str, premises_str = split_clause(clause_str)
premises = []
conclusion = None
if conclusion_str:
conclusion = Atom.from_str(conclusion_str)
for p in premises_str:
premises.append(Atom.from_str(p))
return cls(conclusion, premises)
if __name__ == "__main__":
if len(sys.argv) == 4:
kb = create_kb(sys.argv[1])
queries = get_clauses_from_file(sys.argv[2])
with open(sys.argv[3], 'w') as out_file:
for query in queries:
out_file.write(str(query) + '\n')
out_file.write(to_str(kb.ask(query)) + '\n\n')
# Demo
else:
# All men are mortal.
# Socrates is a man.
premises = ['mortal(X) :- man(X).', 'man("Socrates").']
# Is Socrates mortal?
query = ':- mortal("Socrates").'
premise_clauses = [HornClause.from_str(x) for x in premises]
kb = KnowledgeBase(premise_clauses)
query_clause = HornClause.from_str(query)
# Yes, he is.
response = kb.ask(query_clause)[0]
assert response
# This is how it works
conclusion = 'mortal("Socrates")'
argument = kb.make_argument(Atom.from_str(conclusion))
print(argument)
