Anchor: A female swimmer is practicing her stroke in a pool.
Entailed: A human swimming.
Contradiction: Nobody is swimming.
Contradiction: The institutional structure of the U. S. government had nothing to do with the postal network. 
Contradiction: It gets you into trouble if you try to keep up.
Contradiction: I had to do it, even though mostly elderly people were watching television.
Contradiction: A horse race in progress.