David Roberts
fat realization

Fat realization of a simplicial space $X_{•}=X:{\Delta }^{\mathrm{op}}\to \mathrm{Top}$ is defined as the coend of the associated $\Delta$-space:

$${\Delta }_i^{\mathrm{op}}\hookrightarrow {\Delta }^{\mathrm{op}}\to \mathrm{Top}$$\Delta_i^{op} \hookrightarrow \Delta^{op} \to Top

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