user: Question: Leopold VI, Duke of Austria is the father-in-law of which person?
Columns: ['Father', 'Birth', 'Marriage', 'Became Queen', 'Ceased to be Queen', 'Death', 'Spouse']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Otto II, Margrave of Meissen', '1160+', '1178', '1198', '1199', '2 Feb 1211', 'Ottokar I']
SQL:

assistant: SELECT "Spouse" FROM "Table" WHERE "Father" = 'Leopold VI, Duke of Austria';