Anchor: One person is rock climbing while another person is holding the rope and watching from below.
Entailed: a person is climbing while a safety man holds the rope.
Contradiction: a man is lowering a man down a cliff face with a rope.
Contradiction: The runners are racing go-karts.
Contradiction: Two people sit on a bus.
Contradiction: Julius Ceaser. 
Contradiction: a man is riding a mountain bike