Auxiliary free constructions for explicit embeddings of recursive groups

2023/09/06 by Vahagn H. Mikaelian, Mikaelian, Vahagn H. · 1 citation
Computer Science · Mathematics · #20E06 #20E07 #20F05 #FOS: Mathematics #Finite Group Theory Research #Geometric and Algebraic Topology #Group Theory (math.GR) #semigroups and automata theory

paper · pdf · doi:10.48550/arxiv.2309.03030

openalex publication_date 2023/09/06 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

An auxiliary free construction *_i=1^r(K_i, L_i, t_i)_M based on HNN-extensions and on generalized free product of groups with amalgamated subgroups is suggested, and some of its basic properties are displayed. The proposed construction is a generalization of a series of structures used by Higman for embeddings of recursive groups into finitely presented groups, and also for certain structures we recently applied in the research on embeddings of recursive groups. Usage of this technical tool substantially simplifies some embedding methods for recursive groups. A few technical results on specific subgroups in the suggested *-constructions, in the HNN-extensions of groups, and in free products of groups with amalgamated subgroup are proved. The obtained properties are applied to build infinitely generated benign subgroups inside free groups of small rank.

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