Firstly, we talk about the general result of coherence due to Power-Kelly-Blackwell and Lack. Then, we show how this motivates the study of a 2-dimensional version of Eduardo Dubuc's adjoint triangle theorem.

At last, we show what the proofs of the (bi)adjoint triangle theorems have to do with descent (in dimension 1 and 2).

This work is part of my PhD studies under the supervision of Maria Manuel Clementino.