We always do our very best to include pictures of kittens wherever possible — and if it's not kittens, then we are equally happy with rabbits, whales, or even ants.

That's not entirely gratuitous: we do have a number of articles exploring mathematics that is related to animals. In this year's advent calendar we bring you all of these articles to enjoy during a quiet night by the fire, hopefully with a cat purring on your lap. Happy reading and merry Christmas!

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