Table: chess_players_comparison_2
Columns: position
best_year
best_2_year_period
best_3_year_period
best_5_year_period
best_10_year_period
best_15_year_period

Question: Which best 3-year period has a best 15-year period of smyslov; kasparov, and a Position of 5?
SQL: SELECT "best_3_year_period" FROM chess_players_comparison_2 WHERE "best_15_year_period" = 'smyslov; kasparov' AND "position" = 5

Question: Which best 5-year period has a best 15-year period of alekhine; lasker?
SQL: SELECT "best_5_year_period" FROM chess_players_comparison_2 WHERE "best_15_year_period" = 'alekhine; lasker'

Question: Which best 10-year period has a best 2-year period of petrosian?
SQL: SELECT "best_10_year_period" FROM chess_players_comparison_2 WHERE "best_2_year_period" = 'petrosian'

Question: Which Position has a best 3-year period of petrosian?
SQL: SELECT MAX("position") FROM chess_players_comparison_2 WHERE "best_3_year_period" = 'petrosian'