Anchor: One, whom Dave recognized as the leader with the snetha-knife, scowled.
Entailed: Dave realized that the scowling one with the snetha-knife was the leader.
Contradiction: Dave had never seen a snetha-knife before. 
Contradiction: An old man is walking the neighboorhood.
Contradiction: a man surfing
Contradiction: A man is cleaning his car window.
Contradiction: Humans dancing