Twenty years ago, Thomas and Monique were married. One month before their wedding, Thomas and Monique signed a valid prenuptial agreement in which each of them waived "any property rights in the estate or property of the other to which he or she might otherwise be legally entitled upon the termination of their marriage by death or divorce." Seventeen years ago, Thomas executed a valid will, which provided as follows: "I, Thomas, leave my entire estate to my wife, Monique. However, if I should hereafter have children, then I leave three-fourths of my estate to my wife, Monique, and one-fourth of my estate to my children who survive me, in equal shares." is the will valid