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The Stacks project

Example 4.2.13. Given a category \mathcal{C} and an object X\in \mathop{\mathrm{Ob}}\nolimits (\mathcal{C}) we define the category of objects over X, denoted \mathcal{C}/X as follows. The objects of \mathcal{C}/X are morphisms Y\to X for some Y\in \mathop{\mathrm{Ob}}\nolimits (\mathcal{C}). Morphisms between objects Y\to X and Y'\to X are morphisms Y\to Y' in \mathcal{C} that make the obvious diagram commute. Note that there is a functor p_ X : \mathcal{C}/X\to \mathcal{C} which simply forgets the morphism. Moreover given a morphism f : X'\to X in \mathcal{C} there is an induced functor F : \mathcal{C}/X' \to \mathcal{C}/X obtained by composition with f, and p_ X\circ F = p_{X'}.


Comments (5)

Comment #2541 by Zili Zhang on

In 33.4.8 (which refers to 7.24 and then refers here), the big etale site is defined to be . So I wonder in this example do we require the morphism belongs to ? Since according to the comment after definition 50.27.3, objects in the big etale site over scheme are not required to be etale over .

Comment #2574 by on

In this example, given objects and of we have That is all.

Comment #6707 by on

Here is an undefined control sequence \Mor. Because of that we can't see what's written. Is it possible to make necessary changes?

Comment #6710 by on

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