Die Untergruppen der freien Gruppen

  title={Die Untergruppen der freien Gruppen},
  author={Otto Schreier},
  journal={Abhandlungen aus dem Mathematischen Seminar der Universit{\"a}t Hamburg},
  • O. Schreier
  • Published 1 December 1927
  • Mathematics
  • Abhandlungen aus dem Mathematischen Seminar der Universität Hamburg
The diameter of products of finite simple groups
Following partially a suggestion by Pyber, we prove that the diameter of a product of non-abelian finite simple groups is bounded linearly by the maximum diameter of its factors. For completeness, we
G R ] 3 F eb 2 01 4 Finiteness results for subgroups of finite extensions
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The residual torsion-free nilpotence of the commutator subgroup of a knot group has proven to be an important property with applications to ribbon concordance and bi-orderability. In a lecture,
Group extensions and graphs
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Schreier Graphs and Ergodic Properties of Boundary Actions
This thesis is broadly concerned with two problems: investigating the ergodic properties of boundary actions, and investigating various properties of Schreier graphs. Our main result concerning the
On amalgamation of partially ordered monoids
On the Word Problem for Tensor Products and Amalgams of Monoids
We prove that the word problem for the free product with amalgamation S *UT of monoids can be undecidable, even when S and T are finitely presented monoids with word problems that are decidable in
A converse to Schreier's index-rank formula
In "Subgroups of free profinite groups and large subfields of Q" (Israel J. Math. 39 (1981), no. 1-2, pages 25-45; MR 617288) A. Lubotzky and L. van den Dries raise the question whether a finitely
Graph isomorphisms in quasi-polynomial time
Let us be given two graphs $\Gamma_1$, $\Gamma_2$ of $n$ vertices. Are they isomorphic? If they are, the set of isomorphisms from $\Gamma_1$ to $\Gamma_2$ can be identified with a coset $H\cdot\pi$