Description
Reflection-positive fully extended invertible field theories on manifolds with twisted spin structures provide homotopical classifications for fermionic SPTs. Free fermion SPTs, a subset, are classified by K-theory. Generalizing work of Freed--Hopkins, we define and compute homotopical "free-to-interacting maps" between these classifications for the special case of the "Bott spiral" of SPTs studied originally by Queiroz--Khalaf--Stern. Time permitting, I will discuss some subtleties of our construction, such as compatibility with dimensional reduction, continuous versus discrete symmetry types, and the lack of interacting Morita invariance.