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Enigmas & puzzles

By Ian Stewart   January 2007

Desperate housecats Janet and Fred Tompkins own four cats—Absalom, Booboo, Catnip and Dodo. When the Tompkinses go out, they leave the cats in the kitchen, which has a catflap so that the cats can go outside. This is the only exit and entrance. One day Janet and Fred left the cats, and all four quickly developed an urgent need to go outside.

“If Catnip and Absalom are indoors, they fight unless I’m there to stop it,” said Dodo.

“Yes, and if you and Booboo are indoors, you fight unless I’m there to stop you,” Absalom pointed out.

“Yes, and…

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