A REIDEMEISTER-SCHREIER THEOREM FOR FINITELY L-PRESENTED GROUPS

We prove a variant of the well-known Reidemeister-Schreier Theorem for finitely L-presented groups. More precisely, we prove that each finite index subgroup of a finitely L-presented group is itself finitely L-presented. Our proof is constructive and it yields a finite L-presentation for the subgroup. We further study conditions on a finite index subgroup of an invariantly finitely L-presented group to be invariantly L-presented itself.

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  • Mathematisches Institut
  • Georg-August Universit¨at zu G¨ottingen Bunsenstraße 3–5
  • G¨ottingen, Germany
  • e-mail: rhartung@uni-math.gwdg.de