[For the entire collection see Zbl 0584.00013.] The authors construct, by enumeration, a torsion abelian group $G=A\oplus D$ (which is thus constructive) with a non-constructible reduced subgroup A answering a question of N. G. Hisamiev. Moreover, as a consequence, an answer to a question by Yu. L. Ershov is provided: This constructible group is such that its divisible subgroup D is completely enumerable in a constructive enumeration of the group G, but it is not completely recursive in any constructivization of the group G.
Reviewer: R.Dimitrić