When is a function a fold or an unfold?

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When is a function a fold or an unfold?

We give a necessary and sufficient condition for when a set-theoretic function can be written using the recursion operator fold, and a dual condition for the recursion operator unfold. The conditions are simple, practically useful, and generic in the underlying datatype.

Bibliographic Details
Main Authors:	Gibbons, Jeremy, Hutton, Graham, Altenkirch, Thorsten
Format:	Conference or Workshop Item
Published:	Elsevier Science 2001
Online Access:	https://eprints.nottingham.ac.uk/28196/

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