Question: when was the four color map problem solved
[{'answer': '1976', 'provenance': [{'wikipedia_id': '10949', 'title': 'Four color theorem', 'start_paragraph_id': 2, 'start_character': 37, 'end_paragraph_id': 2, 'end_character': 41, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]