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 "2-1710426-2" WHERE "best 15-year period" = 'Smyslov; Kasparov' AND "Position" = 5.0;

Question: Which best 5-year period has a best 15-year period of Alekhine; Lasker?
SQL: SELECT "best 5-year period" FROM "2-1710426-2" 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 "2-1710426-2" WHERE "best 2-year period" = 'Petrosian';

Question: Which Position has a best 3-year period of Petrosian?
SQL: SELECT MAX("Position") FROM "2-1710426-2" WHERE "best 3-year period" = 'Petrosian';