Non-expansive directions for ℤ2 actions

Michael Hochman*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


We show that any direction in the plane occurs as the unique non-expansive direction of a ℤ2 action, answering a question of Boyle and Lind. In the case of rational directions, the subaction obtained is non-trivial. We also establish that a cellular automaton acting on a subshift can have zero Lyapunov exponents and at the same time act sensitively; and, more generally, for any positive real θ there is a cellular automaton acting on an appropriate subshift with λ+= -λ-=θ.

Original languageAmerican English
Pages (from-to)91-112
Number of pages22
JournalErgodic Theory and Dynamical Systems
Issue number1
StatePublished - Feb 2011
Externally publishedYes


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