ScalingStacks

Proof. Recall that for a Segal space $(d_{0},d_{2})\colon W_{2}\xrightarrow{\sim}W_{1}\times_{W_{0}}W_{1}$, so that $W_{2}\times_{W_{1}}W_{0}\xrightarrow{\sim}(W_{1}\times_{W_{0}}W_{1})\times_{W_{1}}W_{0}\approx W_{1}$ and $W_{0}\times_{W_{1}}W_{2}\xrightarrow{\sim}W_{0}\times_{W_{1}}(W_{1}\times_{W_{0}}W_{1})\approx W_{1}$. ∎