Exercise 1 (p. 195)

For a given object G in a category 𝒞, the category 𝒞/G has, as objects, objects of 𝒞 equipped with a given 𝒞-sorting {X \xrightarrow{s} G} and, as maps, commutative triangles in 𝒞

...

For example, in Session 12, Exercise 3, a category modeling kinship relations was considered as 𝒞/G where an object of 𝒞 = 𝑺↻↻ is thought of as a set of people equipped with father and mother endomaps and G is the object of genders. On the other hand, in Exercise 17 of Article III, another description was given in terms of two sets and four structural maps. Explain in what sense these two descriptions give the 'same' category.