Tullio Ceccherini-Silberstein

  1. A Garden of Eden theorem for linear subshifts.

    Authors: Tullio Ceccherini-Silberstein, Michel Coornaert
    Subjects: Dynamical Systems
    Abstract

    Let $G$ be an amenable group and let $V$ be a finite-dimensional vector space
    over an arbitrary field $\K$.

    We prove that if $X \subset V^G$ is a strongly irreducible linear subshift of
    finite type and

    $\tau \colon X \to X$ is a linear cellular automaton, then $\tau$ is
    surjective if and only if it is pre-injective. We also prove that if $G$ is
    countable and $X \subset V^G$ is a strongly irreducible linear subshift, then
    every injective linear cellular automaton $\tau \colon X \to X$ is surjective.

  2. Context-free pairs of groups I: Context-free pairs and graphs.

    Authors: Tullio Ceccherini-Silberstein, Wolfgang Woess
    Subjects: Group Theory
    Abstract

    Let $G$ be a finitely generated group, $A$ a finite set of generators and $K$
    a subgroup of $G$. We call the pair $(G,K)$ context-free if the set of all
    words over $A$ that reduce in $G$ to an element of $K$ is a context-free
    language. When $K$ is trivial, $G$ itself is called context-free; context-free
    groups have been classified more than 20 years ago in celebrated work of Muller
    and Schupp as the virtually free groups.

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