Which heavyweight boxer holds the record for the most knockouts in title fights?
{'directed': True, 'multigraph': False, 'graph': {}, 'nodes': [{'type': 'QUESTIONS_ENTITY', 'name_': 'Q11338576', 'id': 0, 'label': 'boxer'}, {'type': 'QUESTIONS_ENTITY', 'name_': 'Q281678', 'id': 1, 'label': 'heavyweight'}, {'type': 'INTERNAL', 'name_': 'Q273206', 'id': 2, 'label': 'Joe Louis'}, {'type': 'INTERNAL', 'name_': 'Q16510064', 'id': 3, 'label': 'sporting event'}, {'type': 'INTERNAL', 'name_': 'Q28829877', 'id': 4, 'label': 'sports terminology'}, {'type': 'ANSWER_CANDIDATE_ENTITY', 'name_': 'Q188362', 'id': 5, 'label': 'Rocky Marciano'}, {'type': 'INTERNAL', 'name_': 'Q65125420', 'id': 6, 'label': 'Jersey Joe Walcott vs. Rocky Marciano'}, {'type': 'QUESTIONS_ENTITY', 'name_': 'Q668642', 'id': 7, 'label': 'knockout'}, {'type': 'INTERNAL', 'name_': 'Q7767462', 'id': 8, 'label': 'The Super Fight'}, {'type': 'INTERNAL', 'name_': 'Q12362855', 'id': 9, 'label': 'game'}], 'links': [{'name_': 'P106', 'source': 2, 'target': 0, 'label': 'occupation'}, {'name_': 'P2416', 'source': 2, 'target': 1, 'label': 'sports discipline competed in'}, {'name_': 'P31', 'source': 6, 'target': 3, 'label': 'instance of'}, {'name_': 'P1346', 'source': 6, 'target': 5, 'label': 'winner'}, {'name_': 'P31', 'source': 7, 'target': 4, 'label': 'instance of'}, {'name_': 'P161', 'source': 8, 'target': 2, 'label': 'cast member'}, {'name_': 'P161', 'source': 8, 'target': 5, 'label': 'cast member'}, {'name_': 'P279', 'source': 9, 'target': 3, 'label': 'subclass of'}, {'name_': 'P31', 'source': 9, 'target': 4, 'label': 'instance of'}]}