Anchor: She may have forgotten to bolt the door into the passage when she went to bed, and have got up later, towards morning, and bolted it then."
Entailed: She might have forgotten to lock the door.
Contradiction: She would never forget to lock the door.
Contradiction: We use an alternative valuation procedure to estimate how much premature mortality we have encountered.
Contradiction: I don't use credit cards very often. 
Contradiction: Mount Charleston is private property and can't be hiked.
Contradiction: They are doing something.