Quotient Object

A quotient object of a Congruence X ← p 1 R → p 2 X subscript 𝑝 1 ← 𝑋 𝑅 subscript 𝑝 2 → 𝑋 X\xleftarrow{p_{1}}R\xrightarrow{p_{2}}X in a Category 𝒞 𝒞 \mathcal{C} is an object X / R 𝑋 𝑅 X/R along with a map ι : X → X / R : 𝜄 → 𝑋 𝑋 𝑅 \iota:X\to X/R such that the diagram

R𝑅{{R}}X𝑋{{X}}X/R𝑋𝑅{{X/R}}p1subscript𝑝1\scriptstyle{p_{1}}p2subscript𝑝2\scriptstyle{p_{2}}ι𝜄\scriptstyle{\iota}

is a Coequaliser Diagram. If we unfold this definition using Generalized Elements, we see that it gives us the "usual" definition of a quotient; EG, the universal object X → 𝜄 X / R 𝜄 → 𝑋 𝑋 𝑅 X\xrightarrow{\iota}X/R with the property that for all Γ Γ \Gamma -generalized elements x , y : Γ → X : 𝑥 𝑦 → Γ 𝑋 x,y:\Gamma\to X with R ⁢ ( x , y ) 𝑅 𝑥 𝑦 R(x,y) , ι ⁢ ( x ) = ι ⁢ ( y ) 𝜄 𝑥 𝜄 𝑦 \iota(x)=\iota(y) .

Examples