Anchor: It became a challenge to integrate the work of different observers if they focused their attention on different topics from site to site.
Entailed: Integrating the work done by different observers had become a challenge.
Contradiction: It was very easy to integrate all of the work from the various observers.
Contradiction: A man is riding in his car.
Contradiction: Two dogs are fighting.
Contradiction: Two dogs run down the hallway.
Contradiction: Music is being played.