Arthur and Diana Ebanks owned three properties in the Cayman Islands in joint tenancy. With respect to joint tenancies, Cayman law is the same as U.S. law. When the Ebanks divorced, the decree did not change the tenancy in which the properties were held. On the same day as the divorce filing, Arthur executed a will providing that "any property in my name and that of another as joint tenants . . . will pass to the survivor, and I instruct my Personal Representative to make no claim thereto." Four years later, Arthur died. His brother Curtis, the personal representative of his estate, asserted that Arthur's interest in the Cayman properties was part of the estate. Diana said that the sole interest in the properties was hers. Who do the Cayman properties belong to? Why?