A group G is said to be rigid if it contains a normal series G = G1 > G2 > . . . > Gm > Gm+1 = 1, whose quotients Gi/Gi+1 are Abelian and, treated as right ℤ[G/Gi]-modules, are torsion-free. A rigid group G is divisible if elements of the quotient Gi/Gi+1 are divisible by nonzero elements of the ring ℤ[G/Gi]. Every rigid group is embedded in a divisible one. Our main result is the theorem which reads as follows. Let G be a divisible rigid group. Then the coincidence of ∃-types of same-length tuples of elements of the group G implies that these tuples are conjugate via an automorphism of G. As corollaries we state that divisible rigid groups are strongly ℵ0-homogeneous and that the theory of divisible m-rigid groups admits quantifier elimination down to a Boolean combination of ∃-formulas.
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Translated from Algebra i Logika, Vol. 57, No. 6, pp. 733-748, November-December, 2018.
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Romanovskii, N.S. Divisible Rigid Groups. III. Homogeneity and Quantifier Elimination. Algebra Logic 57, 478–489 (2019). https://doi.org/10.1007/s10469-019-09518-2
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DOI: https://doi.org/10.1007/s10469-019-09518-2