Anchor: Initially, as a conservative starting point, suppose the postal service is at breakeven with no discounts and no presort volume.
Entailed: Assume the postal service is at breakeven as a starting point.
Contradiction: There is no postal service.
Contradiction: The children are dry
Contradiction: It is windy enough to fly a kite.
Contradiction: I don't want to know that.
Contradiction: Someone exclaims the names Tuppence and Julius.