Contents - 2017

• Cubical simplicial volume
  Clara Löh and Christian Plankl
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• Brouwer degree, domination of manifolds, and groups presentable by products
  Pierre de la Harpe
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Contents - 2014

• Poincaré's conjecture
  Klaus Volkert
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Contents - 2013

• Fake lens spaces
  Tibor Macko
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• Lens spaces in dimension three: a history
  Klaus Volkert
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• Poincaré's cube manifolds
  Klaus Volkert
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• Poincaré's homology sphere
  Klaus Volkert
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• Projective plane: a history
  Klaus Volkert
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• Space forms: a history
  Klaus Volkert
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• 1-manifolds
  Oleg Viro
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Contents - 2012

• Aspherical manifolds
  Wolfgang Lück
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Contents - 2011

• Super manifolds: an incomplete survey
  Henning Hohnhold, Stephan Stolz and Peter Teichner
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• Simplicial volume
  Clara Löh
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• Hirzebruch surfaces
  Diarmuid Crowley and Matthias Kreck
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• Bordism
  Taras Panov
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• Complex bordism
  Taras Panov
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• Formal group laws and genera
  Taras Panov
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• 5-manifolds: 1-connected
  Diarmuid Crowley
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Brouwer degree, domination of manifolds, and groups presentable by products

Pierre de la Harpe

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Abstract

For oriented connected closed manifolds of the same dimension, there is a transitive relation: M dominates N, or M >= N, if there exists a continuous map of non-zero degree from M onto N. Section 1 is a reminder on the notion of degree (Brouwer, Hopf), Section 2 shows examples of domination and a first set of obstructions to domination due to Hopf, and Section 3 describes obstructions in terms of Gromov's simplicial volume. In Section 4 we address the particular question of when a given manifold can (or cannot) be dominated by a product. These considerations suggest a notion for groups (fundamental groups), due to D. Kotschick and C. Löh: a group is presentable by a product if it contains two infinite commuting subgroups which generate a subgroup of finite index. The last section shows a small sample of groups which are not presentable by products; examples include appropriate Coxeter groups.

Keywords

Brouwer degree, domination of manifolds, simplicial volume

Mathematical Subject Classification 2010

Primary: 55M25, 57N65

Publication