ScalingStacks

0NPL

Proposition 9.20. The functor VV (9.16) inverts Morita equivalences.

0NPM

Proof. It suffices to show that V⁑(βˆ’)V(-) sends maps of shape π’œβ†’Idem⁑(π’œ){\mathcal{A}}\mathchoice{\longrightarrow}{\rightarrow}{\rightarrow}{\rightarrow}\Idem({\mathcal{A}}) to isomorphisms. Consider the following diagram

π’œ\textstyle{{\mathcal{A}}\ignorespaces\ignorespaces\ignorespaces\ignorespaces\ignorespaces\ignorespaces\ignorespaces\ignorespaces}P\scriptstyle{P}ℱκ​(π’œ)\textstyle{{\mathcal{F}}_{\kappa}({\mathcal{A}})\ignorespaces\ignorespaces\ignorespaces\ignorespaces\ignorespaces\ignorespaces\ignorespaces\ignorespaces}ℱκ​(P)\scriptstyle{{\mathcal{F}}_{\kappa}(P)}Σκ​(π’œ)\textstyle{\Sigma_{\kappa}({\mathcal{A}})\ignorespaces\ignorespaces\ignorespaces\ignorespaces}Σκ​(P)\scriptstyle{\Sigma_{\kappa}(P)}Idem⁑(π’œ)\textstyle{\Idem({\mathcal{A}})\ignorespaces\ignorespaces\ignorespaces\ignorespaces}ℱκ​(Idem⁑(π’œ))\textstyle{{\mathcal{F}}_{\kappa}(\Idem({\mathcal{A}}))\ignorespaces\ignorespaces\ignorespaces\ignorespaces}Σκ​(Idem⁑(π’œ)).\textstyle{\Sigma_{\kappa}(\Idem({\mathcal{A}}))\,.}

PropositionΒ 2.18 implies that ℱκ​(P){\mathcal{F}}_{\kappa}(P) is an equivalence. Therefore, since both rows are strict-exact sequences and Ho⁑(π’œ)\Ho({\mathcal{A}}) and Ho⁑(Idem⁑(π’œ))\Ho(\Idem({\mathcal{A}})) differ by direct summands, we conclude that Σκ​(P)\Sigma_{\kappa}(P) is an equivalence. The definition of the functor V⁑(βˆ’)V(-) allow us to conclude the proof. ∎

Original mathematics by the credited authors. Source collection and HTML conversion remain in progress.

Andrew J. Blumberg, David Gepner, Goncalo Tabuada

Original source: arXiv:1001.2282v4