Table schema:
CREATE TABLE table_15001681_1 (womens_doubles VARCHAR, year VARCHAR, womens_singles VARCHAR, mens_doubles VARCHAR)

Question: In the year 2006, the womens singles had no competition and the mens doubles were roland hilti kilian pfister, what were the womens doubles
SQL: SELECT womens_doubles FROM table_15001681_1 WHERE womens_singles = "no competition" AND mens_doubles = "Roland Hilti Kilian Pfister" AND year = 2006