This paper deals with Kan extensions in a weak double category. Absolute Kan extensions are closely related to the orthogonal adjunctions introduced in a previous paper. The pointwise case is treated by introducing internal comma objects, which can be defined in an arbitrary double category.
Keywords: weak double category, weak double functor, Kan extension, adjoint functor, comma object
2000 MSC: 8D05, 18A40, 18A25
Theory and Applications of Categories,
Vol. 20, 2008,
No. 8, pp 152-185.
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