CREATE TABLE table_9529 ("Date" TEXT, "Tournament" TEXT, "Winning score" TEXT, "Margin of victory" TEXT, "Runner ( s ) -up" TEXT)

What tournament was on May 31, 1987?
SELECT "Tournament" FROM table_9529 WHERE "Date" = 'may 31, 1987'
SELECT "Tournament" FROM "table_9529" WHERE "Date" = 'may 31, 1987'