On free pro-\(C\)-products of pro-\(C\)-groups. (English) Zbl 0581.20030
Let \(G\) be the free product of two groups \(A\) and \(B\) within the class of pro-\(C\)-groups for some class \(C\) of finite groups. Sketches of proofs are given for two theorems:
Theorem 1. Any element \(g\in G\) of finite order is conjugate to some element in \(A\cup B\);
Theorem 2. \(A\) contains the centralizer in \(G\) of any of its elements \(a\neq 1\).
Theorem 2 yields an answer to a question of W. D. Geyer: a maximal abelian subgroup of the free profinite group on countably many generators can be any procyclic group \(\neq 1\).
Theorem 1. Any element \(g\in G\) of finite order is conjugate to some element in \(A\cup B\);
Theorem 2. \(A\) contains the centralizer in \(G\) of any of its elements \(a\neq 1\).
Theorem 2 yields an answer to a question of W. D. Geyer: a maximal abelian subgroup of the free profinite group on countably many generators can be any procyclic group \(\neq 1\).
Reviewer: Yu. N. Mukhin
MSC:
20E18 | Limits, profinite groups |
20E06 | Free products of groups, free products with amalgamation, Higman-Neumann-Neumann extensions, and generalizations |
20E07 | Subgroup theorems; subgroup growth |