Anchor: Perennial wants to take roots! Too late, you short-lived perennial! A student yelled out from a window somewhere.
Entailed: A student was yelling about perennials.
Contradiction: The perennial took root. 
Contradiction: We never had this forum, and nothing of value occurred here.
Contradiction: Boys stand with a chair on sand.
Contradiction: A man in a yellow headband and white shirt plays tennis.
Contradiction: Leonardo da Vinci was a genius designer, as shown by his work at Fontainebleau.