CREATE TABLE table_name_61 (best_3_year_period VARCHAR, best_15_year_period VARCHAR, position VARCHAR)
Which best 3-year period has a best 15-year period of smyslov; kasparov, and a Position of 5?
SELECT best_3_year_period FROM table_name_61 WHERE best_15_year_period = "smyslov; kasparov" AND position = 5