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Feb 11, 2014 at 22:14 comment added Dominik Kwietniak You are right, I only commented to clarify and better understand your statement, since your first sentence may be read as: It is never the case that...
Feb 11, 2014 at 22:14 vote accept Dominik Kwietniak
Feb 11, 2014 at 16:22 comment added Algernon I have shown how you could find a counter-example that refutes the statement "a $k$-block $v$ ($k\ge n$) is a synchronizing block for $X$ if and only if $\psi^{(k)}(v)$ is a synchronizing block for $Y$". For that, you only need one synchronizing shift $X$ whose synchronizing blocks are all of length at least $2$. An example would be the shift space of all sequences in $\{0,1,2\}^\mathbb{Z}$ in which between every two consecutive occurrences of $11$, there is at most one occurrence of $2$.
Feb 11, 2014 at 15:19 comment added Dominik Kwietniak But it may be not true that all synchronizing blocks have length at least two - there are plenty of synchronizing shifts with a synchronizing symbol (one letter word)... Moreover, identity map is always a conjugacy and it clearly preserves the set of synchronizing words. If I understand your claim correctly, you have proved that if the minimal length of a synchronizing word is at least 2, then no $n$-block map for $n\ge2$ can preserve the set of synchronizing words.
Feb 10, 2014 at 12:44 history answered Algernon CC BY-SA 3.0