A universal characterisation of codescent objects

Alexander S. Corner

In this work we define a 2-dimensional analogue of extranatural transformation and use these to characterise codescent objects. They will be seen as universal objects amongst pseudo-extranatural transformations in a similar manner in which coends are universal objects amongst extranatural transformations. Some composition lemmas concerning these transformations are introduced and a Fubini theorem for codescent objects is proven using the universal characterisation description.

Keywords: Codescent object, pseudo-extranatural, Fubini

2010 MSC: 18D05, 18D10

Theory and Applications of Categories, Vol. 34, 2019, No. 24, pp 684-713.

Published 2019-09-02.


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