Anchor: The GAO as an institution, and the Comptroller General as an officer of the legislative branch, assist the Congress in exercising its responsibilities under the Constitution to oversee, investigate, and legislate.
Entailed: The GAO helps Congress exercise its responsbilitiies. 
Contradiction: The GAO prevents Congress from exercising its responsibilities. 
Contradiction: Water spills over the edge of a waterfall.
Contradiction: A cart pulled by a donkey.
Contradiction: Two women at the beach are sleeping on towels.
Contradiction: The boys with the pickup truck, rifle and beer driving down the road.