Anchor:  Unlike other islands of the French West Indies, Martinique has poisonous snakes, and walking off a marked forest trail is not recommended.
Entailed: Walking off marked forest trails is not recommended in Martinique because it has poisonous snakes, unlike other islands of the French West Indies. 
Contradiction: Martinique is the only island of the French West Indies that doesn't have poisonous snakes, so walking off the trails is safe. 
Contradiction: The dog is lying on the couch.
Contradiction: The dog is outside.
Contradiction: Someone is taking a picture with no trees in sight.
Contradiction: Commercial radio services have obligations.