Almost open semigroup actions

  • Jorge Iglesias
  • Aldo Portela
Research Article


In this paper we prove that if a semigroup is almost open then it is sensitive or there exists a residual set of points of equicontinuity. As a consequence we obtain a sufficient condition for sensitivity that generalizes that given in Kontorovich and Megrelishvili (Semigroup Forum 76:133–141, 2008).


Semigroups actions Transitivity Sensitivity 



We thank the referee for many useful observations and providing the proofs of the many propositions. We also thank the financial support by the Program MATHAMSUD (France, Chile and Uruguay).


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Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2018

Authors and Affiliations

  1. 1.IMERL, Facultad de IngenieriaUniversidad de La RepúblicaMontevideoUruguay

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