Berarducci–Peterzil–Pillay's interpretability conjecture for finite central extensions

Let GG be a definably connected definable group in an o-minimal structure MM, and let ZZ be a finite central subgroup. Write \Extd(G,Z)\Ext_d(G,Z) for the definable second cohomology group and \Ext(G,Z)\Ext(G,Z) for the abstract second cohomology group. The natural inclusion

\Extd(G,Z)\Ext(G,Z)\Ext_d(G,Z)\hookrightarrow \Ext(G,Z)

is defined by viewing definable extensions as abstract extensions.

Berarducci–Peterzil–Pillay's conjecture. The natural inclusion

\Extd(G,Z)\Ext(G,Z)\Ext_d(G,Z)\hookrightarrow \Ext(G,Z)

is an isomorphism.

This is the cohomological reformulation of the conjecture that every abstract finite central extension of a definably connected definable group is naturally interpretable in the o-minimal structure. It is known for abelian groups and, by the theorem stated in the paper, for definably connected solvable definable groups; the general case remains open.

Sources & referencesView supporting material

Primary source

Elías Baro and Daniel Palacín, “Finite central extensions of o-minimal groups”, arXiv:2407.16440 (2025).

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