Anchor: Although they knew each other from school; although their groups were defined by flimsy, irrelevant criteria; and although self-interest was not served; they discriminated faithfully.
Entailed: They discriminated faithfully despite knowing each other.
Contradiction: They did not discriminate each other.
Contradiction: A dog eats a treat.
Contradiction: It is horrendous.
Contradiction: A man is playing a piano.
Contradiction: A gentleman is sitting on a dock with a bottle of water.