def make_argument(self, conclusion: Atom):
"""
Constructs an argument that leads to conclusion.
:param conclusion: Atom - conclusion
:return: str - string that describes argument
"""
if not (conclusion.is_ground()):
raise ValueError('Invalid conclusion')
else:
query_conclusion_str = ':-' + str(conclusion) + '.'
if self.ask(HornClause.from_str(query_conclusion_str))[0]:
s = ''
known_clauses = self.get_clauses(conclusion.predicate)
for known_clause in known_clauses:
subs_dict = unify(known_clause.conclusion, conclusion)
if subs_dict:
substituted_clause = known_clause.substitute(subs_dict)
query = HornClause(None, substituted_clause.premises)
found, solutions = self.ask(query)
if found:
if solutions:
substituted_query = query.substitute(solutions[0])
else:
substituted_query = query
for p in substituted_query.premises:
s += str(p) + '.\n'
s += str(known_clause) + '\n'
s += '\u2234 ' + str(conclusion)
break
else:
s = 'Argument does not exist.'
return s
