IPM Calendar 
Monday 6 December 2021   Today  
Events for day: Wednesday 06 October 2021    
           15:30 - 17:30     Mathematical Logic Weekly Seminar
On the Reconstruction of non $aleph_0$-Categorical Theories, and some Remarks on 8Witnesses in Continuous Logic


Let $T$ be an $aleph_0$-categorical theory in first order logic, $M$ its countable model, and $G(T) = mathrm{Aut}(M)$ with the topology of pointwise convergence.
A classical result, due to Coquand (and appearing in a paper by Ahlbrandt and Ziegler) asserts that two aleph0-categorical theories $T$ and $T'$ are bi-interpretable if and only if $G(T)$ and $G(T')$ are isomorphic as topological groups.
Moreover, one can reconstruct from $G(T)$ a theory $T'$ that is bi-interpretable with $T$.

I will discuss a generalisation of this result to arbitrary complete theories in a countable language, at the cost of replacin ...