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LeanPool.RegtsSevenster.RS.Classical.Deligne.TwistDatum

The odd twist of a duality datum #

A self-dual object of the ambient category makes the free module it generates self-dual over any commutative base: the duality datum over the trivial base is carried onto the free module and then base-changed, and both steps preserve the zigzag laws. For an odd line the self-duality is the square trivialisation, so tensoring a duality datum with the line datum and transporting along the twist shuffle gives the odd twist of a duality datum, zigzag laws included.