3 papers
math.GR2026
Subgroups with all finite lifts isomorphic are conjugate
Ido Karshon, Alexander Lubotzky, D. B. McReynolds +2
We show that for non-conjugate subgroups and of a finite group there exists an extension of (by a finite group) in which the pre-images of and are n…
math.GR2025
Relatively hyperbolic groups, Grothendieck pairs, and uncountable profinite ambiguity among fibre products
Martin R. Bridson, Alan W. Reid
These notes expand upon our lectures on {\em profinite rigidity} at the international colloquium on randomness, geometry and dynamics, organised by TIFR Mumbai at IISER Pune in Jan…
math.GR2025
Absolute profinite rigidity, direct products, and finite presentability
M. R. Bridson, A. W. Reid, R. Spitler
We prove that there exist finitely presented, residually finite groups that are profinitely rigid in the class of all finitely presented groups but not in the class of all finitely…