Anchor: Mariachi singers and folk dance groups can usually be seen here on weekends.
Entailed: On the weekends is when Mariachi singers and folk dance groups are usually observable.
Contradiction: Mariachi singers can be seen here every Friday.
Contradiction: The country music stations never play them.
Contradiction: We both enjoy playing golf, but she doesn't enjoy hunting.
Contradiction: The condition in the organization make addressing one principle before another unworkable. 
Contradiction: The men's weapons were blue with fire.