Strict stability of extension types

  title={Strict stability of extension types},
  author={Jonathan Weinberger},
. We show that the extension types occurring in Riehl–Shulman’s work on synthetic ( ∞ , 1)-categories can be interpreted in the intended seman- tics in a way so that they are strictly stable under substitution. The splitting method used here is due to Voevodsky in 2009. It was later generalized by Lumsdaine–Warren to the method of local universes . MSC2020 : 03B38 (Primary); 03G30, 18N45, 18N50, 18N60, 55U35 (Sec- ondary) 
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