Star sorts, Lelek fans, and the reconstruction of non-$\aleph_0$-categorical theories in continuous logic
Résumé
We prove a reconstruction theorem valid for arbitrary theories in continuous (or classical) logic in a countable language, that is to say that we provide a complete bi-interpretation invariant for such theories, taking the form of an open Polish topological groupoid.
More explicitly, for every such theory $T$ we construct a groupoid $\mathbf{G}^*(T)$ that only depends on the bi-interpretation class of $T$, and conversely, we reconstruct from $\mathbf{G}^*(T)$ a theory that is bi-interpretable with $T$.
The basis of $\mathbf{G}^*(T)$ (namely, the set of objects, when viewed as a category) is always homeomorphic to the Lelek fan.
We break the construction of the invariant into two steps.
In the second step we construct a groupoid from any \emph{reconstruction sort}, while in the first step such a sort is constructed.
This allows us to place our result in a common framework with previously established ones, which only differ by their different choice of a reconstruction sort.
Domaines
Logique [math.LO]Origine | Fichiers produits par l'(les) auteur(s) |
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