4 papers · 1 filter
Malnormal Subgroups of Finitely Presented Groups
Francis Wagner
The following refinement of the Higman embedding theorem is proved: A finitely generated group is recursively presented if and only if there exists a quasi-isometric malnormal…
Quasilinear Emulation of Turing Machines by S-machines
Bogdan Chornomaz, Francis Wagner
We prove that for any , a non-deterministic Turing machine with time complexity can be emulated by an -machine with time and space complexiti…
Torsion Subgroups of Groups with Quadratic Dehn Function
Francis Wagner
We construct the first examples of finitely presented groups with quadratic Dehn function containing a finitely generated infinite torsion subgroup. These examples are "optimal" in…
Torsion Subgroups of Groups with Cubic Dehn Function
Francis Wagner
We construct the first examples of finitely presented groups with cubic Dehn function containing a finitely generated infinite torsion subgroup. Moreover, we show that any infinite…