On Residually Finite Semigroups of Cellullar Automata
  We prove that if $M$ is a monoid and $A$ a finite set with more than one element, then the residual finiteness of $M$ is equivalent to that of the monoid consisting of all cellular automata over $M$ with alphabet $A$. 
Tullio Ceccherini-Silberstein and Michel Coornaert
math.GR math.DS