A woman who takes a vow while betrothed, divorces that same day, gets betrothed to another that same day - the father can revoke her vow and the second (or last in this kind of chain) can revoke it. That is, she is always under her father's auspices, as a young woman, or under her husband's, but she hasn't aged into her own authority. Plus, the verses that explain the bottom lines of these cases. Also, a dispute between Beit Hillel and Beit Shammai regarding the nature of revoking the woman's vow.