CREATE TABLE table_66231 ("!Event" FLOAT, "Round" TEXT, "Surface" TEXT, "Winner" TEXT, "Opponent" TEXT, "Result" TEXT)

Which Event has a Surface of semifinal, and a Winner of hard (i)?
SELECT MAX("!Event") FROM table_66231 WHERE "Surface" = 'semifinal' AND "Winner" = 'hard (i)'
SELECT MAX("!Event") FROM "table_66231" WHERE "Surface" = 'semifinal' AND "Winner" = 'hard (i)'